Experimentally Induced Reductions in Alcohol Consumption and Brain, Cognitive, and Clinical Outcomes in Older Persons With and Those Without HIV Infection (30-Day Challenge Study): Protocol for a Nonrandomized Clinical Trial

BACKGROUND

Both alcohol consumption and HIV infection are associated with worse brain, cognitive, and clinical outcomes in older adults. However, the extent to which brain and cognitive dysfunction is reversible with reduction or cessation of drinking is unknown.

OBJECTIVE

The 30-Day Challenge study was designed to determine whether reduction or cessation of drinking would be associated with improvements in cognition, reduction of systemic and brain inflammation, and improvement in HIV-related outcomes in adults with heavy drinking.

METHODS

The study design was a mechanistic experimental trial, in which all participants received an alcohol reduction intervention followed by repeated assessments of behavioral and clinical outcomes. Persons were eligible if they were 45 years of age or older, had weekly alcohol consumption of 21 or more drinks (men) or 14 or more drinks (women), and were not at high risk of alcohol withdrawal. After a baseline assessment, participants received an intervention consisting of contingency management (money for nondrinking days) for at least 30 days followed by a brief motivational interview. After this, participants could either resume drinking or not. Study questionnaires, neurocognitive assessments, neuroimaging, and blood, urine, and stool samples were collected at baseline, 30 days, 90 days, and 1 year after enrollment.

RESULTS

We enrolled 57 persons with heavy drinking who initiated the contingency management protocol (mean age 56 years, SD 4.6 years; 63%, n=36 male, 77%, n=44 Black, and 58%, n=33 people with HIV) of whom 50 completed 30-day follow-up and 43 the 90-day follow-up. The planned study procedures were interrupted and modified due to the COVID-19 pandemic of 2020-2021.

CONCLUSIONS

This was the first study seeking to assess changes in brain (neuroimaging) and cognition after alcohol intervention in nontreatment-seeking people with HIV together with people without HIV as controls. Study design strengths, limitations, and lessons for future study design considerations are discussed. Planned analyses are in progress, after which deidentified study data will be available for sharing.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03353701; https://clinicaltrials.gov/study/NCT03353701.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/53684.

Associations between physical exercise type, fluid intelligence, executive function, and processing speed in the oldest-old (85 +)

BACKGROUND

While much is known about the effects of physical exercise in adult humans, literature on the oldest-old (≥ 85 years old) is sparse. The present study explored the relationship between self-reported engagement in physical exercise and cognition in the oldest-old.

METHODS

The sample included 184 cognitively healthy participants (98 females, MoCA mean score = 24.81) aged 85 to 99 years old (mean = 88.49 years). Participants completed the Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire and a cognitive battery including NIH-TB, Coding, Symbol Search, Letter Fluency, and Stroop task. Three groups of participants - sedentary (n = 58; MoCA mean score = 24; 36 females; mean age = 89.03), cardio (n = 60; MoCA mean score = 25.08; 29 females; mean age = 88.62), and cardio + strength training (n = 66; MoCA mean score = 25.28; 33 females; mean age = 87.91) - were derived from responses on CHAMPS.

RESULTS

Analyses controlled for years of education, NIH-TB Crystallized Composite, and metabolic equivalent of tasks. The cardio + strength training group had the highest cognitive performances overall and scored significantly better on Coding (p < 0.001) and Symbol Search (p < 0.05) compared to the sedentary group. The cardio + strength training group scored significantly better on Symbol Search, Letter Fluency, and Stroop Color-Word compared to the cardio group (p < 0.05).

CONCLUSIONS

Our findings suggest self-reported exercise in the oldest-old is linked to better performance on cognitive measures of processing speed and executive functioning, and that there may be a synergistic effect of combining aerobic and resistance training on cognition.

The association of depression and anxiety symptoms to three different types of activities of daily living in persons with and without HIV

Mood disorders are highly prevalent in people living with HIV (PLWH) and represent a potential contributor to functional impairment in activities of daily living. We aimed to determine if (1) Anxiety and depression symptoms were independently associated with impairments in basic self-care, role functioning, and social functioning and (2) PLWH differentially experienced impairments due to mood symptoms compared to those without HIV. Data for this study were obtained from 150 individuals (87 PLWH, 61% male, mean age = 44) via a cross-sectional study on alcohol and HIV-associated brain dysfunction. The Beck Anxiety Inventory (BAI) and the Center for Epidemiologic Studies Depression Scale (CES-D) were used to assess anxiety and depressive symptoms. Higher anxiety symptoms were associated with role functioning impairment, while higher depressive and anxiety symptoms were each associated with social functioning impairment. As depressive symptoms increased, PLWH were 3x more likely to have impairments in role functioning compared to those without HIV. HIV status did not interact with mood symptoms to affect basic self-care or social functioning. Overall, mood symptoms are associated with different types of functional impairment, and improved management of mood symptoms could lead to improved role and social functioning.

Presurgical microstructural coherence predicts cognitive change for bariatric surgery patients

OBJECTIVE

This observational study examined the relationship between presurgical white matter microstructural coherence and cognitive change after weight loss. It was hypothesized that higher baseline fractional anisotropy (FA) would predict greater baseline and change cognition.

METHODS

A sample of 24 adults (BMI ≥ 35 kg/m2 ) underwent neuropsychological assessment at baseline and 12 weeks after bariatric surgery. A magnetic resonance imaging brain scan was administered at baseline and processed through Tract-Based Spatial Statistics to compute FA in white matter tracts of interest. Composite scores for attention, learning, processing speed, executive function, verbal fluency, working memory, and overall cognition were calculated.

RESULTS

As expected, FA in some tracts of interest was significantly (p < 0.05) positively associated with change in cognition. Inverse relationships were observed between baseline FA and presurgical cognition, which may be explained by increased medial and radial diffusivity and preserved axonal diffusivity. Cognition generally improved after surgery; however, relative but clinically nonsignificant deterioration was observed on learning measures. Poorer baseline cognitive performance was associated with greater postsurgical cognitive improvement.

CONCLUSIONS

Presurgical microstructural coherence is associated with magnitude of cognitive change after weight loss. An observed reduction in learning suggests that bariatric surgery may lead to negative outcomes in some cognitive domains, at least temporarily.

Effects of sleep disturbance on trauma-focused psychotherapy outcomes in posttraumatic stress disorder: A systematic review

This study aimed to synthesize existing research on the effects of sleep disturbances on trauma-focused psychotherapy outcomes in adults with posttraumatic stress disorder (PTSD). A systematic review using PubMed, PsycINFO, Embase, Web of Science, and PTSDpubs was performed up to April 2021. Two independent reviewers screened articles for inclusion, performed data extraction, and assessed risk of bias and certainty of the evidence. Narrative synthesis was conducted based on the type of sleep disorder symptom assessed. Sixteen primary studies were included in this review, the majority of which had a high overall risk of bias. Results suggested that sleep disorder symptoms were associated with higher overall PTSD severity across treatment; however, they did not interfere with treatment effectiveness, with the exception of sleep-disordered breathing. Improvements in insomnia, sleep duration, and sleep quality during treatment were associated with greater treatment gains. Certainty of the evidence ranged from low to very low. These results suggest that it may not be necessary to address sleep disorder symptoms prior to initiating trauma-focused psychotherapy. Instead, concurrent treatment of sleep- and trauma-related symptoms may be most beneficial. Continued research is needed to clarify the mechanistic relationship between sleep and treatment outcomes and to guide clinical decision-making.

Change in medial frontal cerebral metabolite concentrations following bariatric surgery

Obesity is associated with adverse effects on brain health, including an increased risk of neurodegenerative diseases. Changes in cerebral metabolism may underlie or precede structural and functional brain changes. While bariatric surgery is known to be effective in inducing weight loss and improving obesity-related medical comorbidities, few studies have examined whether it may be able to improve brain metabolism. In the present study, we examined changes in cerebral metabolite concentrations in participants with obesity who underwent bariatric surgery. Thirty-five patients with obesity (body mass index ≥ 35 kg/m2 ) were recruited from a bariatric surgery candidate nutrition class. They completed single voxel proton magnetic resonance spectroscopy at baseline (presurgery) and within 1 year postsurgery. Spectra were obtained from a large medial frontal brain region using a PRESS sequence on a 3-T Siemens Verio scanner. The acquisition parameters were TR = 3000 ms and TE = 37 ms. Tissue-corrected metabolite concentrations were determined using Osprey. Paired t-tests were used to examine within-subject change in metabolite concentrations, and correlations were used to relate these changes to other health-related outcomes, including weight loss and glycated hemoglobin (HbA1c ), a measure of blood sugar levels. Bariatric surgery was associated with a reduction in cerebral choline-containing compounds (Cho; t [34] = - 3.79, p < 0.001, d = -0.64) and myo-inositol (mI; t [34] = - 2.81, p < 0.01, d = -0.47) concentrations. There were no significant changes in N-acetyl-aspartate, creatine, or glutamate and glutamine concentrations. Reductions in Cho were associated with greater weight loss (r = 0.40, p < 0.05), and reductions in mI were associated with greater reductions in HbA1c (r = 0.44, p < 0.05). In conclusion, participants who underwent bariatric surgery exhibited reductions in cerebral Cho and mI concentrations, which were associated with improvements in weight loss and glycemic control. Given that elevated levels of Cho and mI have been implicated in neuroinflammation, reduction in these metabolites after bariatric surgery may reflect amelioration of obesity-related neuroinflammatory processes. As such, our results provide evidence that bariatric surgery may improve brain health and metabolism in individuals with obesity.

Resting-state network functional connectivity before and after bariatric surgery

BACKGROUND

Bariatric surgery is an increasingly popular treatment for patients with severe obesity and related health issues (e.g., diabetes, cardiovascular disease). Studies have identified alterations in functional connectivity both in obesity and following surgical treatment for severe obesity.

OBJECTIVE

This study aimed to assess brain function via resting-state within-network connectivity in bariatric surgery patients with severe obesity.

SETTING

University hospital.

METHODS

Thirty-four bariatric surgery patients completed functional neuroimaging at baseline and postoperatively (goal, 12 weeks; actual, 16 weeks, on average). They also self-reported health information. Baseline resting-state functional connectivity (RSFC) was predicted by baseline age, body mass index (BMI), continuous positive airway pressure use, and reported history of rheumatoid arthritis and type 2 diabetes. Change in RSFC was assessed using the same predictors. This model was run with and without controlling for baseline RSFC.

RESULTS

Higher baseline BMI predicted lower baseline RSFC in 3 networks. Lower baseline RSFC also was related to rheumatoid arthritis and type 2 diabetes. Difference between baseline and follow-up RSFC was strongly negatively associated with baseline RSFC. Controlling for baseline RSFC, type 2 diabetes negatively predicted RSFC difference.

CONCLUSIONS

RSFC may reflect brain dysfunction in patients with obesity and related diseases. That less connectivity at baseline predicted greater positive change suggests that RSFC may be a biomarker of neurocognitive improvement following bariatric surgery. Diseases more prevalent in patients with obesity (e.g., rheumatoid arthritis and type 2 diabetes) along with elevated BMI negatively affect RSFC likely through inflammatory pathways.

Anger, agency, risk and action: a neurobehavioral model with proof-of-concept in healthy young adults

Introduction

Anger can engender action by individuals and groups. It is thus important to understand anger's behavioral phenotypes and their underlying neural substrates. Here, we introduce a construct we term agentic anger, a negatively valenced internal state that motivates action to achieve risky goals. We evaluate our neurobehavioral model via testable hypotheses in two proof-of-concept studies.

Study 1 Methods

Study 1 used the Incentive Balloon Analogue Risk Task in a within-subjects, repeated measures design in 39 healthy volunteers to evaluate: (a) impact of blockade of reward on agentic anger, assessed by self-reports of negative activation (NA), (b) impact of achievement of reward on exuberance, assessed by self-reports of positive activation (PA), (c) the interrelationship of these valenced states, and (d) their relationship with personality.

Study 1 Results

Task-induced NA was positively correlated with task-induced PA, risk-taking on the task and trait Social Potency (SP), a measure of trait agency and reward sensitivity on the Multidimensional Personality Questionnaire Brief-Form.

Study 2 Methods

Study 2 assessed functional MRI response to stakes for risk-taking in healthy volunteers receiving 20 mg d-amphetamine in a double-blinded, placebo-controlled crossover design (N = 10 males), providing preliminary information on ventral striatal response to risky rewards during catecholamine activation.

Study 2 Results

Trait SP and task-induced PA were strongly positively related to catecholamine-facilitated BOLD response in the right nucleus accumbens, a brain region where DA prediction error signal shapes action value and selection. Participants' task-induced NA was strongly positively related with trait SP and task-induced PA, replicating the findings of Study 1.

Discussion

Together these results inform the phenomenology and neurobiology of agentic anger, which recruits incentive motivational circuitry and motivates personal action in response to goals that entail risk (defined as exposure to uncertainty, obstacles, potential harm, loss and/or financial, emotional, bodily, or moral peril). Neural mechanisms of agency, anger, exuberance, and risk-taking are discussed, with implications for personal and group action, decision-making, social justice, and behavior change.

Resting state connectivity in people living with HIV before and after stopping heavy drinking

Background

Heavy alcohol use in people living with HIV (PLWH) has widespread negative effects on neural functioning. It remains unclear whether experimentally-induced reduction in alcohol use could reverse these effects. We sought to determine the effects of 30-days drinking cessation/reduction on resting state functional connectivity in people with and without HIV.

Methods

Thirty-five participants (48.6% PLWH) demonstrating heavy alcohol use attempted to stop drinking for 30 days via contingency management (CM). MRI was acquired at baseline and after thirty days, and functional connectivity across five resting-state fMRI (rsfMRI) networks was calculated with the Conn toolbox for Matlab and examined in relation to transdermal alcohol concentration (TAC) recorded by the ankle-worn secure continuous remote alcohol monitor (SCRAM) and self-reported alcohol use (timeline follow-back; TLFB). Associations between alcohol use and reduction, HIV status, functional connectivity, and change in functional connectivity across five major rsfMRI networks were determined relative to the pre- and post-CM timepoints.

Results

Baseline resting-state functional connectivity was not significantly associated with average TAC-AUC during the pre-CM period, though higher self-reported alcohol use over the preceding 30 days was significantly associated with higher baseline connectivity within the Dorsal Attention Network (DAN; p-FDR < 0.05). Baseline connectivity within the Salience network was significantly negatively related to objective drinking reduction after intervention (DAN; p-FDR < 0.05), whereas baseline connectivity within the Limbic network was positively associated with self-reported drinking reduction (p-FDR < 0.05). Change in between-networks functional connectivity after intervention was significantly positively associated with biosensor-confirmed drinking reduction such that higher reduction was associated with stronger connectivity between the limbic and fronto-parietal control networks (p-FDR < 0.05). PLWH with lower DAN connectivity at baseline demonstrated poorer alcohol reduction than those with higher DAN connectivity at baseline.

Discussion

Lower resting-state functional connectivity of the Salience network significantly predicted stronger drinking reduction across all participants, suggesting a potential biomarker for reduced susceptibility to the environmental and social cues that often make alcohol use reduction attempts unsuccessful. Increased between-networks connectivity was observed in participants with higher alcohol reduction after CM, suggesting a positive benefit to brain connectivity associated with reduced drinking. PLWH with lower baseline DAN connectivity may not benefit as greatly from CM for alcohol reduction.

The Effects of Transcutaneous Vagus Nerve Stimulation on Functional Connectivity Within Semantic and Hippocampal Networks in Mild Cognitive Impairment

Better treatments are needed to improve cognition and brain health in people with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Transcutaneous vagus nerve stimulation (tVNS) may impact brain networks relevant to AD through multiple mechanisms including, but not limited to, projection to the locus coeruleus, the brain's primary source of norepinephrine, and reduction in inflammation. Neuropathological data suggest that the locus coeruleus may be an early site of tau pathology in AD. Thus, tVNS may modify the activity of networks that are impaired and progressively deteriorate in patients with MCI and AD. Fifty patients with MCI (28 women) confirmed via diagnostic consensus conference prior to MRI (sources of info: Montreal Cognitive Assessment Test (MOCA), Clinical Dementia Rating scale (CDR), Functional Activities Questionnaire (FAQ), Hopkins Verbal Learning Test - Revised (HVLT-R) and medical record review) underwent resting state functional magnetic resonance imaging (fMRI) on a Siemens 3 T scanner during tVNS (left tragus, n = 25) or sham control conditions (left ear lobe, n = 25). During unilateral left tVNS, compared with ear lobe stimulation, patients with MCI showed alterations in functional connectivity between regions of the brain that are important in semantic and salience functions including regions of the temporal and parietal lobes. Furthermore, connectivity from hippocampi to several cortical and subcortical clusters of ROIs also demonstrated change with tVNS compared with ear lobe stimulation. In conclusion, tVNS modified the activity of brain networks in which disruption correlates with deterioration in AD. These findings suggest afferent target engagement of tVNS, which carries implications for the development of noninvasive therapeutic intervention in the MCI population.

Functional connectivity of brain networks during semantic processing in older adults

The neural systems underlying semantic processing have been characterized with functional neuroimaging in young adults. Whether the integrity of these systems degrade with advanced age remains unresolved. The current study examined functional connectivity during abstract and concrete word processing. Thirty-eight adults, aged 55–91, engaged in semantic association decision tasks during a mixed event-related block functional magnetic resonance imaging (fMRI) paradigm. During the semantic trials, the task required participants to make a judgment as to whether pairs were semantically associated. During the rhyme trials, the task required participants to determine if non-word pairs rhymed. Seeds were placed in putative semantic hubs of the left anterior middle temporal gyrus (aMTG) and the angular gyrus (AG), and also in the left inferior frontal gyrus (IFG), an area considered important for semantic control. Greater connectivity between aMTG, AG, and IFG and multiple cortical areas occurred during semantic processing. Connectivity from the three seeds differed during semantic processing: the left AG and aMTG were strongly connected with frontal, parietal, and occipital areas bilaterally, whereas the IFG was most strongly connected with other frontal cortical areas and the AG in the ipsilateral left hemisphere. Notably, the strength and extent of connectivity differed for abstract and concrete semantic processing; connectivity from the left aMTG and AG to bilateral cortical areas was greater during abstract processing, whereas IFG connectivity with left cortical areas was greater during concrete processing. With advanced age, greater connectivity occurred only between the left AG and supramarginal gyrus during the processing of concrete word-pairs, but not abstract word-pairs. Among older adults, robust functional connectivity of the aMTG, AG, and IFG to widely distributed bilateral cortical areas occurs during abstract and concrete semantic processing in a manner consistent with reports from past studies of young adults. There was not a significant degradation of functional connectivity during semantic processing between the ages of 55 and 85 years. As the study focused on semantic functioning in older adults, a comparison group of young adults was not included, limiting generalizability. Future longitudinal neuroimaging studies that compare functional connectivity of young and older adults under different semantic demands will be valuable.

The Association Between Peripheral Oxytocin Levels and Depressive Symptoms in People With HIV

OBJECTIVE

Depression is common in people with HIV (PWH), yet little is known about the mechanisms contributing to depressive symptoms in PWH. Previous research across a range of populations has suggested a relationship between the neuropeptide oxytocin and depressive symptoms, with variable directionality. This article investigated the association between peripheral oxytocin levels and depressive symptoms in PWH.

METHODS

Unextracted oxytocin serum concentrations were assayed in 79 PWH (44% female, mean age = 34.35 [8.5], mean body mass index = 25.69 [5.46], mean CD4 = 516.60 [271.15]) who also completed the Center for Epidemiologic Studies Depression Scale (CES-D). CES-D items were evaluated in an exploratory factor analysis (EFA), and the relationships between oxytocin, total CES-D score, and the resulting EFA factors were analyzed with multivariate linear regressions conducted in R. Multiple regression models were used to adjust for age, sex, body mass index, CD4, and education.

RESULTS

Contrary to hypothesized, higher peripheral oxytocin levels were associated with higher CES-D total scores with a small-to-moderate effect size ( β = 0.26, p = .009). Following Bonferroni correction, oxytocin was not significantly associated with any of the five factors identified from the EFA: depressed affect, positive affect, appetite, cognitive symptoms, or perceived failure ( p values > .042). Small effect sizes were found for the depressed affect ( β = 0.22) and perceived failure ( β = 0.21) factors ( p values > .042).

CONCLUSIONS

In a sample of predominately Black or African American individuals with HIV, higher oxytocin was associated with higher total depressive symptoms. In addition, this relationship was slightly stronger than those of specific depressive symptoms. These findings warrant further study into the role of oxytocin in mood symptoms within PWH.

Somatosensory impairment of the feet is associated with higher activation of prefrontal cortex during walking in older adults

BACKGROUND

Over-activation of prefrontal cortex during walking has been reported in older adults versus young adults. Heighted activity in prefrontal cortex suggests a shift toward an executive control strategy to control walking. A potential contributing factor is degraded functioning of pattern-generating locomotor circuits in the central nervous system that are important to walking coordination. Somatosensory information is a crucial input to these circuits, so age-related impairment of somatosensation would be expected to compromise the neural control of walking. The present study tested the hypothesis that poorer somatosensation in the feet of older adults will be associated with greater recruitment of the prefrontal cortex during walking. This study also examines the extent to which somatosensory function and prefrontal activity are associated with performance on walking and balance assessments.

METHODS

Forty seven older adults (age 74.6 ± 6.8 years; 32 female) participated in walking assessments (typical walking and obstacle negotiation) and Berg Balance Test. During walking, prefrontal activity was measured with functional near infrared spectroscopy (fNIRS). Participants also underwent somatosensory testing with Semmes-Weinstein monofilaments.

RESULTS

The primary findings is that worse somatosensory monofilament level was associated with greater prefrontal cortical activity during typical walking (r = 0.38, p = 0.008) and obstacle negotiation (r = 0.40, p = 0.006). For the obstacle negotiation task, greater prefrontal activity was associated with faster walking speed (p = 0.004). Poorer somatosensation was associated with slower typical walking speed (p = 0.07) and obstacles walking speed (p < 0.001), as well as poorer balance scores (p = 0.03).

CONCLUSIONS

The study findings are consistent with a compensation strategy of recruiting prefrontal/executive control resources to overcome loss of somatosensory input to the central nervous system. Future research should further establish the mechanisms by which somatosensory impairments are linked to the neural control and performance of walking tasks, as well as develop intervention approaches.

The Marijuana Associated Planning and Long-term Effects (MAPLE) Study: Protocol of a Longitudinal Cohort of Marijuana Use and Health Outcomes in Persons living with HIV (Preprint)

Background

Marijuana use is common in persons with HIV, but there is limited evidence of its relationship with potential health benefits or harms.

Objective

The Marijuana Associated Planning and Long-term Effects (MAPLE) study was designed to evaluate the impact of marijuana use on HIV-related health outcomes, cognitive function, and systemic inflammation.

Methods

The MAPLE study is a longitudinal cohort study of participants living with HIV who were recruited from 3 locations in Florida and were either current marijuana users or never regular marijuana users. At enrollment, participants completed questionnaires that included detailed marijuana use assessments, underwent interviewer-administered neurocognitive assessments, and provided blood and urine samples. Ongoing follow-ups included brief telephone assessments (every 3 months), detailed questionnaires (annually), repeated blood and urine samples (2 years), and linkage to medical records and statewide HIV surveillance data. Supplemental measures related to intracellular RNA, COVID-19, Alzheimer disease, and the gut microbiome were added after study initiation.

Results

The MAPLE study completed enrollment of 333 persons between 2018 and 2021. The majority of participants in the sample were ≥50 years of age (200/333, 60.1%), male (181/333, 54.4%), cisgender men (173/329, 52.6%), non-Hispanic Black (221/333, 66.4%), and self-reported marijuana users (260/333, 78.1%). Participant follow-up was completed in 2022, with annual updates to HIV surveillance data through at least 2027.

Conclusions

The MAPLE study is the largest cohort specifically designed to understand the use of marijuana and its effects on HIV-related outcomes. The study population has significant diversity across age, sex, gender, and race. The data will help clinicians and public health officials to better understand patterns of marijuana use associated with both positive and negative health outcomes, and may inform recommendations for future clinical trials related to medical marijuana and HIV.

International Registered Report Identifier (IRRID)

DERR1-10.2196/37153

Baseline Neuroimaging Predicts Decline to Dementia From Amnestic Mild Cognitive Impairment

Background and Objectives: Prediction of decline to dementia using objective biomarkers in high-risk patients with amnestic mild cognitive impairment (aMCI) has immense utility. Our objective was to use multimodal MRI to (1) determine whether accurate and precise prediction of dementia conversion could be achieved using baseline data alone, and (2) generate a map of the brain regions implicated in longitudinal decline to dementia. Methods: Participants meeting criteria for aMCI at baseline (N = 55) were classified at follow-up as remaining stable/improved in their diagnosis (N = 41) or declined to dementia (N = 14). Baseline T1 structural MRI and resting-state fMRI (rsfMRI) were combined and a semi-supervised support vector machine (SVM) which separated stable participants from those who decline at follow-up with maximal margin. Cross-validated model performance metrics and MRI feature weights were calculated to include the strength of each brain voxel in its ability to distinguish the two groups. Results: Total model accuracy for predicting diagnostic change at follow-up was 92.7% using baseline T1 imaging alone, 83.5% using rsfMRI alone, and 94.5% when combining T1 and rsfMRI modalities. Feature weights that survived the p < 0.01 threshold for separation of the two groups revealed the strongest margin in the combined structural and functional regions underlying the medial temporal lobes in the limbic system. Discussion: An MRI-driven SVM model demonstrates accurate and precise prediction of later dementia conversion in aMCI patients. The multi-modal regions driving this prediction were the strongest in the medial temporal regions of the limbic system, consistent with literature on the progression of Alzheimer's disease.

Associations of alcohol use, HIV infection, and age with brain white matter microstructure

Heavy drinking and HIV infection are independently associated with damage to the brain's white matter. The purpose of the current study was to investigate whether current alcohol consumption, HIV infection, and associated characteristics were associated with indices of white matter microstructural integrity in people living with HIV (PLWH) and seronegative individuals. PLWH and controls were categorized as non-drinkers, moderate drinkers, or heavy drinkers. White matter fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) were assessed using diffusion tensor imaging (DTI). Voxelwise analyses using tract-based spatial statistics were followed by confirmatory region-of-interest (ROI) analyses. Data from 108 participants (62 PLWH, 46 controls) were suitable for analysis. Average age (± standard deviation) was 45.2 ± 11.1 years, and the sample was 42% female. The majority of PLWH were on antiretroviral therapy (94%) and were virally suppressed (69%). PLWH and controls did not differ on substance use. Heavier alcohol intake was significantly associated with lower FA and higher RD in widespread areas. Heavy drinking was significantly associated with higher AD in a small region. The main effect of HIV was not significant, but a significant HIV-age interaction was observed. Follow-up ROI analyses confirmed the main effect of drinking group and HIV-age interaction. In conclusion, results are consistent with a dose-dependent association of alcohol use with lower white matter microstructural coherence. Concordance between FA and RD findings suggests dysmyelination as a mechanism. Findings underscore the need to address unhealthy alcohol use in HIV-positive and seronegative individuals, the consequences of which may be exacerbated by aging.

Circulating Cytokines Predict 1H-Proton MRS Cerebral Metabolites in Healthy Older Adults

Background: Changes in both circulating cytokines and neurochemical concentrations have been observed in aging. Patterns of change across these factors are associated with age-related pathologies, including neurodegenerative disease. More evidence to define patterns of change that are characteristic of healthy aging is needed, as is an investigation into how age-related changes in blood cytokines and brain neurochemicals may relate to one another in a healthy older adult population.

Methods: Single voxel ¹H-proton magnetic resonance spectroscopy was collected in medial frontal and medial parietal regions. Phosphocholine and glycerophosphocholine (Cho), myo-inositol (MI), N-acetylaspertate and N-acetylasperglutamate (NAA), creatine and phosphocreatine (Cr), and glutamate and glutamine (Glx) were measured in a sample of 83 healthy, cognitively normal adults aged 52–89. Blood data were collected to quantify 12 cytokines: interleukins (IL-) 2, 5, 6, 7, 8, 10, 12, 13, IL-1 β, tumor necrosis factor α (TNF-α), interferon γ (IFN-γ), and IL-17 α. Correlation analyses were performed to assess age relationships between each of these factors. Backward linear regressions were performed. Cytokine data and age were used as predictors of each cerebrospinal fluid (CSF)-corrected metabolite concentration in both voxels.

Results: Associations were identified between a variety of cytokines and concentrations of frontal NAA, Cr, and Glx, and of parietal MI, Cho, NAA, and Cr. In the frontal voxel, NAA was predicted by more IL-1B and less TNF-α, Cr by less TNF-α and more IL-5, and Glx by less TNF-α. In the parietal voxel, MI was predicted by more IL-10 and IL-8 and less IL-2, Cho by more TNF-α and less IL-2, NAA by more IL-1B and TNF-α and less IL-13, IL-2, and IL-7, and Cr by more IL-10 and less IL-2.

Conclusions: Associations were identified between circulating cytokines and neurometabolite concentrations in this sample of older adults. The present results serve as the initial evidence of relationships between circulating cytokines and neurophysiology. Findings invite further investigation to understand the physiological consequences of aging, and how peripheral inflammatory markers may relate to neurochemical concentrations in healthy aging.

Reduced Working Memory is Associated with Heavier Alcohol Consumption History, Role Impairment and Executive Function Difficulties

Both HIV status and heavy alcohol use have been associated with reduced cognitive function, particularly in the domains of working memory and executive function. It is unclear what aspects of working memory and executive function are associated with HIV status and heavy alcohol use and whether performance on these measures are associated with functional impairment. We examined the relationship between HIV, history of heavy alcohol consumption, and HIV/alcohol interaction on speeded tests of frontal inhibitory abilities, a working memory task related to mental manipulation of letters and numbers, cognitive flexibility, and measures of functional impairment. Study participants included 284 individuals (151 HIV +) recruited from two different studies focusing on HIV associated brain dysfunction, one specific to the effects of alcohol, the other specific to the effects of aging. HIV status was not independently associated with working memory and executive function measures. Higher level of alcohol consumption was associated with reduced performance on Letter Number Sequencing. Poorer Letter Number Sequencing performance was associated with role impairment (an inability to do certain kinds of work, housework, or schoolwork) and executive function difficulties. Future studies should examine causal associations and interventions targeting working memory abilities.

A-15 Validity of the NIH Toolbox Cognitive Battery in a Healthy Oldest-Old 85+ Sample

Objective

The NIH Toolbox (NIHTB) Cognitive assessment battery has not been validated in the oldest-old population (85 years and older). Factor analysis of the NIHTB cognitive measures with “gold-standard” measures of the same cognition domains has revealed convergent and discriminant validity of these measures in a young adult population. Here we investigate if there is convergent and discriminant validity among the NIHTB and validated measures in the oldest old.

Methods

An exploratory factor analysis using the principal-axis factor extraction with Varimax rotation was conducted to determine the factor structure of the NIH Toolbox Cognitive Battery and other validated measures of cognition in the healthy oldest-old population. The sample, collected as part of the McKnight Brain Aging Registry, included 170 independent, healthy, community-dwelling adults aged 85+.

Results

Results indicated four factors with eigenvalues exceeding one with 58.6% variance explained. These four factors were interpreted as Memory, Working Memory, Speed/Attention, and Language. NIHTB Dimensional Change Card Sort test was removed due to low correlations with other measures.

Conclusion

Most tests from the NIH Toolbox converged with other tests of the same domain and were discriminable from tests of different domains, especially for memory, working memory, and language. The first factor, Speed/Attention, included attention and processing speed measures, but also canonical executive functioning measures such as Trails B. This overlap indicates that executive functioning tasks that rely on motor speed task demands (like the NIHTB DCCS) may mask preserved aspects of executive function in the oldest old. Further work is needed to confirm this interpretation.

A-3 Cingulo-Opercular and Frontoparietal Control Network Connectivity and Executive Functioning in Older Adults

Objective

Executive functioning is a cognitive domain that typically declines with normal aging. Age-related disrupted connectivity in cingulo-opercular (CON) and frontoparietal control (FPCN) resting-state networks is associated with worse performance across various executive functioning tasks. This study examines the relationships between CON and FPCN connectivity and executive functioning performance in older adults across three subdomains: working memory, inhibition, and set-shifting.

Methods

274 healthy older adults (age M = 71.7, SD = 5.1; 87% Caucasian) from a clinical trial at the University of Florida and University of Arizona completed tasks of working memory (Digit Span Backwards [DSB]; Letter Number Sequencing [LNS]), inhibition (Stroop), and set-shifting (Trail Making Test Part B [TMT-B]). Participants underwent resting-state functional magnetic resonance imaging. CONN Toolbox (18b) was used for extracting average within-network connectivity of CON and FPCN. Multiple linear regressions were conducted with average network connectivity predicting performance, controlling for age, sex, education, and scanner.

Results

Greater average CON connectivity was associated with better performance on DSB (β = 0.26, p &lt; 0.001), LNS (β = 0.23, p &lt; 0.001), Stroop (β = 0.24, p &lt; 0.001), and TMT-B (β = −0.26, p &lt; 0.001). Greater average FPCN connectivity was associated with better performance on DSB (β = 0.22, p &lt; 0.001) and LNS (β = 0.18, p = 0.002).

Conclusions

CON connectivity was significantly associated with working memory, inhibition, and set-shifting. FPCN connectivity was significantly associated with working memory. Future research should conduct regional connectivity analyses within these networks to identify intervention targets to improve executive functioning in older adults.

Change in marijuana use and its associated factors among persons living with HIV (PLWH) during the COVID-19 pandemic: Findings from a prospective cohort

BACKGROUND

Emerging literature shows increased drug use during the COVID-19 pandemic. However, limited research has examined the change in marijuana use among persons living with HIV (PLWH). This study aimed to investigate how marijuana use changed in a cohort of PLWH during the first year of the pandemic and identify factors associated with the change.

METHOD

222 PLWH (mean age = 50.2 ± 11.2, 50.9 % female, 14.5 % Hispanic, 64.7 % Black, 15.8 % White, 5 % other, 80.2 % persons using marijuana [at least weekly use], 19.8 % persons not using marijuana) completed a baseline survey on demographics and behavioral/health characteristics between 2018 and 2020 and a brief phone survey between May and October 2020 that assessed changes in marijuana use and overall/mental health, and perceived risks/benefits of marijuana use during the COVID-19 pandemic.

RESULTS

During the pandemic, 64/222(28.8 %) of the whole sample reported increased marijuana use, 36(16.2 %) reported decreased use, and 122(55 %) reported no change. Multinomial logistic regression results indicated that: Compared to those reporting no change, increased marijuana use during the pandemic was associated with more frequent marijuana use and PTSD symptoms at baseline, worsened mental health during the pandemic, and not perceiving marijuana use as a risk factor for COVID-19 infection. More frequent marijuana use at baseline was the only factor significantly associated with decreased marijuana use during the pandemic.

CONCLUSION

The COVID-19 pandemic has resulted in changes in marijuana use among a considerable proportion (45 %) of PLWH. Future research is needed to understand the temporality of the increases in marijuana use with worsening mental health.

Dedifferentiation of Functional Brain Activation Associated With Greater Visual Discrimination Accuracy in Middle-Aged and Older Adults

Neural dedifferentiation refers to an age-related phenomenon whereby brain functions that are localized to specific, distinct, and differentiated brain areas in young adults become less so as people reach more advanced age. Older adults tend to exhibit greater spread of cortical activation on fMRI during cognitive processing compared to younger adults, with evidence that this occurs during visuoperceptual processing. Some age-related functional changes are considered compensatory, but whether dedifferentiation is compensatory is not clearly understood. The current study assessed dedifferentiation and visual discrimination performance during simultaneous match-to-sample tasks from the Visual Assessment Battery (VAB) among 40 healthy middle-aged and older adults using fMRI. Task-relevant regions of interest (ROIs) were created in the dorsal stream for discrimination of spatial location, the ventral stream for shape, and an area encompassing V5 for velocity. Dedifferentiation, or less specificity in functional activation, was associated with greater discrimination accuracy and more years of education. Secondary analyses showed that reduced functional activation in task-relevant ROIs was associated with faster discrimination speed. Age was unassociated with functional activation. Results suggest that dedifferentiation is compensatory. Lack of age effects suggest that other factors beyond age, such as cognitive or brain reserve, may better predict performance when considering cognitive skills that are relatively stable as adults age, such as visual discrimination.

Cerebral Metabolite Concentrations Are Associated With Cortical and Subcortical Volumes and Cognition in Older Adults

Background

Cerebral metabolites are associated with different physiological processes in brain aging. Cortical and limbic structures play important roles in cognitive aging; however, the relationship between these structures and age remains unclear with respect to physiological underpinnings. Regional differences in metabolite levels may be related to different structural and cognitive changes in aging.

Methods

Magnetic resonance imaging and spectroscopy were obtained from 117 cognitively healthy older adults. Limbic and other key structural volumes were measured. Concentrations of N-acetylaspartate (NAA) and choline-containing compounds (Cho) were measured in frontal and parietal regions. Neuropsychological testing was performed including measures of crystallized and fluid intelligence and memory.

Results

NAA in the frontal voxel was associated with limbic and cortical volumes, whereas Cho in parietal cortex was negatively associated with hippocampal and other regional volumes. Hippocampal volume was associated with forgetting, independent of age. Further, parietal Cho and hippocampal volume contributed independent variance to age corrected discrepancy between fluid and crystallized abilities.

Conclusion

These findings suggest that physiological changes with age in the frontal and parietal cortices may be linked to structural changes in other connected brain regions. These changes are differentially associated with cognitive performance, suggesting potentially divergent mechanisms.

Association of Immunosuppression and Viral Load With Subcortical Brain Volume in an International Sample of People Living With HIV

IMPORTANCE

Despite more widely accessible combination antiretroviral therapy (cART), HIV-1 infection remains a global public health challenge. Even in treated patients with chronic HIV infection, neurocognitive impairment often persists, affecting quality of life. Identifying the neuroanatomical pathways associated with infection in vivo may delineate the neuropathologic processes underlying these deficits. However, published neuroimaging findings from relatively small, heterogeneous cohorts are inconsistent, limiting the generalizability of the conclusions drawn to date.

OBJECTIVE

To examine structural brain associations with the most commonly collected clinical assessments of HIV burden (CD4+ T-cell count and viral load), which are generalizable across demographically and clinically diverse HIV-infected individuals worldwide.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study established the HIV Working Group within the Enhancing Neuro Imaging Genetics Through Meta Analysis (ENIGMA) consortium to pool and harmonize data from existing HIV neuroimaging studies. In total, data from 1295 HIV-positive adults were contributed from 13 studies across Africa, Asia, Australia, Europe, and North America. Regional and whole brain segmentations were extracted from data sets as contributing studies joined the consortium on a rolling basis from November 1, 2014, to December 31, 2019.

MAIN OUTCOMES AND MEASURES

Volume estimates for 8 subcortical brain regions were extracted from T1-weighted magnetic resonance images to identify associations with blood plasma markers of current immunosuppression (CD4+ T-cell counts) or detectable plasma viral load (dVL) in HIV-positive participants. Post hoc sensitivity analyses stratified data by cART status.

RESULTS

After quality assurance, data from 1203 HIV-positive individuals (mean [SD] age, 45.7 [11.5] years; 880 [73.2%] male; 897 [74.6%] taking cART) remained. Lower current CD4+ cell counts were associated with smaller hippocampal (mean [SE] β = 16.66 [4.72] mm3 per 100 cells/mm3; P < .001) and thalamic (mean [SE] β = 32.24 [8.96] mm3 per 100 cells/mm3; P < .001) volumes and larger ventricles (mean [SE] β = -391.50 [122.58] mm3 per 100 cells/mm3; P = .001); in participants not taking cART, however, lower current CD4+ cell counts were associated with smaller putamen volumes (mean [SE] β = 57.34 [18.78] mm3 per 100 cells/mm3; P = .003). A dVL was associated with smaller hippocampal volumes (d = -0.17; P = .005); in participants taking cART, dVL was also associated with smaller amygdala volumes (d = -0.23; P = .004).

CONCLUSIONS AND RELEVANCE

In a large-scale international population of HIV-positive individuals, volumes of structures in the limbic system were consistently associated with current plasma markers. Our findings extend beyond the classically implicated regions of the basal ganglia and may represent a generalizable brain signature of HIV infection in the cART era.

Neuroimaging and Cognitive Evidence for Combined HIV-Alcohol Effects on the Central Nervous System: A Review

Alcohol use disorder (AUD) among people living with HIV (PLWH) is a significant public health concern. Despite the advent of effective antiretroviral therapy, up to 50% of PLWH still experience worsened neurocognition, which comorbid AUD exacerbates. We report converging lines of neuroimaging and neuropsychological evidence linking comorbid HIV/AUD to dysfunction in brain regions linked to executive function, learning and memory, processing speed, and motor control, and consequently to impairment in daily life. The brain shrinkage, functional network alterations, and brain metabolite disruption seen in individuals with HIV/AUD have been attributed to several interacting pathways: viral proteins and EtOH are directly neurotoxic and exacerbate each other's neurotoxic effects; EtOH reduces antiretroviral adherence and increases viral replication; AUD and HIV both increase gut microbial translocation, promoting systemic inflammation and HIV transport into the brain by immune cells; and HIV may compound alcohol's damaging effects on the liver, further increasing inflammation. We additionally review the neurocognitive effects of aging, Hepatitis C coinfection, obesity, and cardiovascular disease, tobacco use, and nutritional deficiencies, all of which have been shown to compound cognitive changes in HIV, AUD, and in their comorbidity. Finally, we examine emerging questions in HIV/AUD research, including genetic and cognitive protective factors, the role of binge drinking in HIV/AUD-linked cognitive decline, and whether neurocognitive and brain functions normalize after drinking cessation.

MicroRNA predicts cognitive performance in healthy older adults

The expression of microRNA (miRNA) is influenced by ongoing biological processes, including aging, and has begun to play a role in the measurement of neurodegenerative processes in central nervous system. The purpose of this study is to utilize machine learning approaches to determine whether miRNA can be utilized as a blood-based biomarker of cognitive aging. A random forest regression combining miRNA with biological (brain volume), clinical (comorbid conditions), and demographic variables in 115 typically aging older adults explained the greatest level of variance in cognitive performance compared to the other machine learning models explored. Three miRNA (miR-140-5p, miR-197-3p, and miR-501-3p) were top-ranked predictors of multiple cognitive outcomes (Fluid, Crystallized, and Overall Cognition) and past studies of these miRNA link them to cellular senescence, inflammatory signals for atherosclerotic formation, and potential development of neurodegenerative disorders (e.g., Alzheimer's disease). Several novel miRNAs were also linked to age and multiple cognitive functions, findings which together warrant further exploration linking these miRNAs to brain-derived metrics of neurodegeneration in typically aging older adults.

The neurobiology of wellness: 1H-MRS correlates of agency, flexibility and neuroaffective reserves in healthy young adults

Proton magnetic resonance spectroscopy (¹H-MRS) is a noninvasive imaging technique that measures the concentration of metabolites in defined areas of the human brain in vivo. The underlying structure of natural metabolism-emotion relationships is unknown. Further, there is a wide range of between-person differences in metabolite concentration in healthy individuals, but the significance of this variation for understanding emotion in healthy humans is unclear. Here we investigated the relationship of two emotional constructs, agency and flexibility, with the metabolites glutamate and glutamine (Glx), N-acetylaspartate (tNAA), choline (Cho), creatine (tCr), and myo-inositol (Ins) in the right dorsal anterior cingulate cortex (dACC) in medically and psychiatrically healthy volunteers (N = 20, 9 female; mean age = 22.8 years, SD = 3.40). The dACC was selected because this region is an integrative hub involved in multiple brain networks of emotion, cognition and behavior. Emotional traits were assessed using the Multidimensional Personality Questionnaire Brief Form (MPQ-BF), an empirically derived self-report instrument with an orthogonal factor structure. Phenotypes evaluated were positive and negative agency (MPQ-BF Social Potency, Aggression), emotional and behavioral flexibility (MPQ-BF Absorption, Control-reversed), and positive and negative affect (MPQ-BF Social Closeness; Stress Reaction, Alienation). The resting concentration of tNAA in the dACC was robustly positively correlated with Absorption (r = +0.56, unadjusted p = .005), moderately positively correlated with Social Potency (r = +0.42, unadjusted p = .03), and robustly negatively correlated with Aggression (r = −0.59, unadjusted p = .003). Absorption and Aggression accounted for substantial variance in tNAA (R² = 0.31, 0.35; combined R² = 0.50), and survived correction for multiple comparisons (Holm-Bonferroni adjusted p = .032, 0.021, respectively). dACC Glx and Cho had modest relationships with behavioral flexibility and social affiliation that did not survive this multiple correction, providing effect sizes for future work. Principal Component Analysis (PCA) revealed a three-factor orthogonal solution indicating specific relationships between: 1) Glx and behavioral engagement; 2) Cho and affiliative bonding; and 3) tNAA and a novel dimension that we term neuroaffective reserves. Our results inform the neurobiology of agency and flexibility and lay the groundwork for understanding mechanisms of natural emotion using ¹H-MRS.

The association of white matter free water with cognition in older adults

BACKGROUND

Extracellular free water within cerebral white matter tissue has been shown to increase with age and pathology, yet the cognitive consequences of free water in typical aging prior to the development of neurodegenerative disease remains unclear. Understanding the contribution of free water to cognitive function in older adults may provide important insight into the neural mechanisms of the cognitive aging process.

METHODS

A diffusion-weighted MRI measure of extracellular free water as well as a commonly used diffusion MRI metric (fractional anisotropy) along nine bilateral white matter pathways were examined for their relationship with cognitive function assessed by the NIH Toolbox Cognitive Battery in 47 older adults (mean age ​= ​74.4 years, SD ​= ​5.4 years, range ​= ​65-85 years). Probabilistic tractography at the 99th percentile level of probability (Tracts Constrained by Underlying Anatomy; TRACULA) was utilized to produce the pathways on which microstructural characteristics were overlaid and examined for their contribution to cognitive function independent of age, education, and gender.

RESULTS

When examining the 99th percentile probability core white matter pathway derived from TRACULA, poorer fluid cognitive ability was related to higher mean free water values across the angular and cingulum bundles of the cingulate gyrus, as well as the corticospinal tract and the superior longitudinal fasciculus. There was no relationship between cognition and mean FA or free water-adjusted FA across the 99th percentile core white matter pathway. Crystallized cognitive ability was not associated with any of the diffusion measures. When examining cognitive domains comprising the NIH Toolbox Fluid Cognition index relationships with these white matter pathways, mean free water demonstrated strong hemispheric and functional specificity for cognitive performance, whereas mean FA was not related to age or cognition across the 99th percentile pathway.

CONCLUSIONS

Extracellular free water within white matter appears to increase with normal aging, and higher values are associated with significantly lower fluid but not crystallized cognitive functions. When using TRACULA to estimate the core of a white matter pathway, a higher degree of free water appears to be highly specific to the pathways associated with memory, working memory, and speeded decision-making performance, whereas no such relationship existed with FA. These data suggest that free water may play an important role in the cognitive aging process, and may serve as a stronger and more specific indicator of early cognitive decline than traditional diffusion MRI measures, such as FA.

Combining Frontal Transcranial Direct Current Stimulation With Walking Rehabilitation to Enhance Mobility and Executive Function: A Pilot Clinical Trial

OBJECTIVES

This pilot study assessed whether frontal lobe transcranial direct current stimulation (tDCS) combined with complex walking rehabilitation is feasible, safe, and shows preliminary efficacy for improving walking and executive function.

MATERIALS AND METHODS

Participants were randomized to one of the following 18-session interventions: active tDCS and rehabilitation with complex walking tasks (Active/Complex); sham tDCS and rehabilitation with complex walking tasks (Sham/Complex); or sham tDCS and rehabilitation with typical walking (Sham/Typical). Active tDCS was delivered over F3 (cathode) and F4 (anode) scalp locations for 20 min at 2 mA intensity. Outcome measures included tests of walking function, executive function, and prefrontal activity measured by functional near infrared spectroscopy.

RESULTS

Ninety percent of participants completed the intervention protocol successfully. tDCS side effects of tingling or burning sensations were low (average rating less than two out of 10). All groups demonstrated gains in walking performance based on within-group effect sizes (d ≥ 0.50) for one or more assessments. The Sham/Typical group showed the greatest gains for walking based on between-group effect sizes. For executive function, the Active/Complex group showed the greatest gains based on moderate to large between-group effect sizes (d = 0.52-1.11). Functional near-infrared spectroscopy (fNIRS) findings suggest improved prefrontal cortical activity during walking.

CONCLUSIONS

Eighteen sessions of walking rehabilitation combined with tDCS is a feasible and safe intervention for older adults. Preliminary effects size data indicate a potential improvement in executive function by adding frontal tDCS to walking rehabilitation. This study justifies future larger clinical trials to better understand the benefits of combining tDCS with walking rehabilitation.

Obstacle Negotiation in Older Adults: Prefrontal Activation Interpreted Through Conceptual Models of Brain Aging

Background and Objectives

The influence of interindividual differences on brain activation during obstacle negotiation and the implications for walking performance are poorly understood in older adults. This study investigated the extent to which prefrontal recruitment during obstacle negotiation is explained by differences in age, executive function, and sex. These data were interpreted according to the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH) framework of brain aging. We also tested the association between prefrontal recruitment and walking performance.

Research Design and Methods

Prefrontal oxygenated hemoglobin concentration (O₂Hb) was measured during typical walking (Typical) and obstacle negotiation (Obstacles) tasks in 50 adults aged 65 years and older using functional near-infrared spectroscopy. The primary outcome was the change in prefrontal recruitment (∆PFR), measured as Obstacles ∆O₂Hb minus Typical ∆O₂Hb. Multiple regression was used to test the relationship between ∆PFR and age, executive function measured by the Trail Making Test, and sex. Pearson's correlation coefficient was used to investigate the association between ∆PFR and the cost of Obstacles walking speed relative to Typical walking.

Results

Age, executive function, and their interaction significantly predicted greater ∆PFR (R ² = 0.34, p = .01). Participants were subgrouped according to age and executive function to examine the interaction effects. Adults of lower age and with lower executive function exhibited greater ∆PFR during Obstacles compared to their peers with higher executive function (p = .03). Adults of advanced age exhibited a ceiling of prefrontal recruitment during obstacle negotiation, regardless of executive function level (p = .87). Greater ∆PFR was significantly associated with a smaller cost of Obstacles (r = 0.3, p = .03).

Discussion and Implications

These findings are consistent with the CRUNCH framework: neural inefficiency where a greater amount of brain activation is needed for task performance at a similar level, compensatory overactivation to prevent a steeper decline in task performance, and capacity limitation with a recruitment ceiling effect.

Cerebrovascular Perfusion among Older Adults with and Without Cardiovascular Disease

BACKGROUND AND PURPOSE

Cardiovascular disease (CVD) encompasses a range of disorders that affect health and functioning in older adults. While cognitive declines have been linked to both cardiovascular and cerebral blood perfusion, protective neurovascular mechanisms raise the question whether cerebrovascular perfusion differs as a function of cardiovascular health status. The present study examined whether cerebrovascular perfusion significantly differs between healthy older adults with and without diagnosed CVD. The study also examined whether previously documented sex differences in cerebral perfusion would be replicated.

METHODS

Twenty CVD patients without significant heart failure and 39 healthy controls were recruited to undergo a comprehensive assessment, including an interview, echocardiogram, and magnetic resonance imaging). Arterial spin labeling was used to quantify cerebral blood perfusion.

RESULTS

Both groups exhibited mean left ventricular ejection fractions that fell within normal limits. In line with previous research, women exhibited significantly higher cerebral perfusion than men. There were no significant group differences in whole brain cerebrovascular perfusion, regional perfusion, or white matter perfusion by patient status after accounting for sex and age.

CONCLUSIONS

These findings suggest that the effects of mild CVD on cerebrovascular perfusion are minimal. Future studies are needed to investigate the mechanisms involved in maintaining cerebrovascular perfusion in the context of altered peripheral perfusion and to determine whether this finding extends to more acute or severe CVD.

ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries

This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors.

History of Alcohol Consumption and HIV Status Related to Functional Connectivity Differences in the Brain During Working Memory Performance

BACKGROUND

Poorer working memory function has previously been associated with alcohol misuse, Human Immunodeficiency Virus (HIV) positive status, and risky behavior. Poorer working memory performance relates to alterations in specific brain networks.

OBJECTIVE

The current study examined if there was a relationship between brain networks involved in working memory and reported level of alcohol consumption during an individual's period of heaviest use. Furthermore, we examined whether HIV status and the interaction between HIV and alcohol consumption was associated with differences in these brain networks.

METHODS

Fifty adults, 26 of whom were HIV positive, engaged in an n-back working memory task (0-back and 2-back trials) administered in a magnetic resonance imaging (MRI) scanner. The Kreek- McHugh-Schluger-Kellogg (KMSK) scale of alcohol consumption was used to characterize an individual's period of heaviest use and correlates well with their risk for alcohol dependence. Connectivity analyses were conducted using data collected during n-back task.

RESULTS

Functional connectivity differences associated with greater alcohol consumption included negative connectivity, primarily from parietal attention networks to frontal networks. Greater alcohol consumption was also associated with positive connectivity from working memory nodes to the precuneus and paracingulate. HIV positive status was associated with more nodes of negative functional connectivity relative to alcohol consumption history alone, particularly in the frontoparietal networks. The HIV positive individuals with heavier drinking history related to negative fronto-parietal connectivity, along with positive connectivity from working memory nodes to mesolimbic regions.

CONCLUSION

Findings allow for a better understanding of brain networks affected by HIV and alcohol and may provide avenues for interventions.

Associations between subclinical depressive symptoms and reduced brain volume in middle-aged to older adults

OBJECTIVES

The associations between subclinical depressive symptoms, as well specific symptom subscales, on brain structure in aging are not completely elucidated. This study investigated the extent to which depressive symptoms were related to brain volumes in fronto-limbic structures in a sample of middle-aged to older adults.

METHOD

Eighty participants underwent structural neuroimaging and completed the Beck Depression Inventory, 2nd Edition (BDI-II), which comprises separate affective, cognitive, and somatic subscales. Gray matter volumes were extracted from the caudal and rostral anterior cingulate, posterior cingulate, hippocampus, and amygdala. Hierarchical regression models examined the relationship between brain volumes and (i) total depressive symptoms and (ii) BDI-II subscales were conducted.

RESULTS

After adjusting for total intracranial volume, race, and age, higher total depressive symptoms were associated with smaller hippocampal volume (p = 0.005). For the symptom subscales, after controlling for the abovementioned covariates and the influence of the other symptom subscales, more somatic symptoms were related to smaller posterior cingulate (p = 0.025) and hippocampal (p < 0.001) volumes. In contrast, the affective and cognitive subscales were not associated with brain volumes in any regions of interest.

CONCLUSION

Our data showed that greater symptomatology was associated with smaller volume in limbic brain regions. These findings provide evidence for preclinical biological markers of major depression and specifically advance knowledge of the relationship between subclinical depressive symptoms and brain volume. Importantly, we observed variations by specific depressive symptom subscales, suggesting a symptom-differential relationship between subclinical depression and brain volume alterations in middle-aged and older individuals.

Progressive brain atrophy in chronically infected and treated HIV+ individuals

Growing evidence points to persistent neurological injury in chronic HIV infection. It remains unclear whether chronically HIV-infected individuals on combined antiretroviral therapy (cART) develop progressive brain injury and impaired neurocognitive function despite successful viral suppression and immunological restoration. In a longitudinal neuroimaging study for the HIV Neuroimaging Consortium (HIVNC), we used tensor-based morphometry to map the annual rate of change of regional brain volumes (mean time interval 1.0 ± 0.5 yrs), in 155 chronically infected and treated HIV+ participants (mean age 48.0 ± 8.9 years; 83.9% male) . We tested for associations between rates of brain tissue loss and clinical measures of infection severity (nadir or baseline CD4+ cell count and baseline HIV plasma RNA concentration), HIV duration, cART CNS penetration-effectiveness scores, age, as well as change in AIDS Dementia Complex stage. We found significant brain tissue loss across HIV+ participants, including those neuro-asymptomatic with undetectable viral loads, largely localized to subcortical regions. Measures of disease severity, age, and neurocognitive decline were associated with greater atrophy. Chronically HIV-infected and treated individuals may undergo progressive brain tissue loss despite stable and effective cART, which may contribute to neurocognitive decline. Understanding neurological complications of chronic infection and identifying factors associated with atrophy may help inform strategies to maintain brain health in people living with HIV.

Relationship of fatigue with cognitive performance in women with early-stage breast cancer over 2 years

OBJECTIVE

Fatigue and cognitive dysfunction are major concerns for women with early-stage breast cancer during treatment and into survivorship. However, interrelationships of these phenomena and their temporal patterns over time are not well documented, thus limiting the strategies for symptom management interventions. In this study, changes in fatigue across treatment phases and the relationship among fatigue severity and its functional impact with objective cognitive performance were examined.

METHODS

Participants (N = 75) were assessed at five time points beginning prior to chemotherapy to 24 months after initial chemotherapy. Fatigue severity and impact were measured on the Brief Fatigue Inventory. Central nervous system (CNS) Vital Signs was used to measure performance based cognitive testing. Temporal changes in fatigue were examined, as well as the relationship between fatigue and cognitive performance, at each time point using linear mixed effect models.

RESULTS

Severity of fatigue varied as a function of phase of treatment. Fatigue severity and its functional impact were moderate at baseline, increased significantly during chemotherapy, and returned to near baseline levels by 2 years. At each time point, fatigue severity and impact were significantly associated with diminished processing speed and complex attention performance.

CONCLUSIONS

A strong association between fatigue and objective cognitive performance suggests that they are likely functionally related. That cognitive deficits were evident at baseline, whereas fatigue was more chemotherapy dependent, implicates that two symptoms share some common bases but may differ in underlying mechanisms and severity over time. This knowledge provides a basis for introducing strategies for tailored symptom management that vary over time.

Cerebral Metabolites on the Descending Limb of Acute Alcohol: A Preliminary 1H MRS Study

AIMS

Chronic alcohol use is associated with cerebral metabolite abnormalities, yet alcohol's acute effects on neurometabolism are not well understood. This preliminary study investigated cerebral metabolite changes in vivo on the descending limb of blood alcohol in healthy moderate drinkers.

METHODS

In a pre/post design, participants (N = 13) completed magnetic resonance imaging (MRI) scans prior to and approximately 5 hours after consuming a moderate dose of alcohol (0.60 grams alcohol per kilogram of body weight). Magnetic resonance spectroscopy (1H MRS) was used to quantify cerebral metabolites related to glutamatergic transmission (Glx) and neuroimmune activity (Cho, GSH, myo-inositol) in the thalamus and frontal white matter.

RESULTS

Breath alcohol concentration (BrAC) peaked at 0.070±0.008% (mean ± standard deviation) and averaged 0.025±0.011% directly prior to the descending limb scan. In the thalamus, Glx/Cr and Cho/Cr were significantly elevated on the descending limb scan relative to baseline. BrAC area under the curve, an index of alcohol exposure during the session, was significantly, positively associated with levels of Glx/Cr, Cho/Cr and GSH/Cr in the thalamus. GSH/Cr on the descending limb was inversely correlated with subjective alcohol sedation.

CONCLUSIONS

This study offers preliminary evidence of alcohol-related increases in Glx/Cr, Cho/Cr and GSH/Cr on the descending limb of blood alcohol concentration. Findings add novel information to previous research on neurometabolic changes at peak blood alcohol in healthy individuals and during withdrawal in individuals with alcohol use disorder.

Neuropsychology of aging

All people want to age "successfully," maintaining functional capacity and quality of life as they reach advanced age. Achieving this goal depends on preserving optimal cognitive and brain functioning. Yet, significant individual differences exist in this regard. Some older adults continue to retain most cognitive abilities throughout their lifetime. Others experience declines in cognitive and functional capacity that range from mild decrements in certain cognitive functions over time to severe dementia among those with neurodegenerative diseases. Even among relatively healthy "successful agers," certain cognitive functions are reduced from earlier levels. This is particularly true for cognitive functions that are dependent on cognitive processing speed and efficiency. Working memory and executive and attentional functions tend to be most vulnerable. Learning and memory functions are also usually reduced, although in the absence of neurodegenerative disease learning and retrieval efficiency rather than memory storage are affected. Other functions, such as visual perception, language, semantics, and knowledge, are often well preserved. Structural, functional, and physiologic/metabolic brain changes correspond with age-associated cognitive decline. Physiologic and metabolic mechanisms, such as oxidative stress and neuroinflammation, may contribute to these changes, along with the contribution of comorbidities that secondarily affect the brain of older adults. Cognitive frailty often corresponds with physical frailty, both affected by multiple exogenous and endogenous factors. Neuropsychologic assessment provides a way of measuring the cognitive and functional status of older adults, which is useful for monitoring changes that may be occurring. Neuroimaging is also useful for characterizing age-associated structural, functional, physiologic, and metabolic brain changes, including alterations in cerebral blood flow and metabolite concentrations. Some interventions that may enhance cognitive function, such as cognitive training, neuromodulation, and pharmacologic approaches, exist or are being developed. Yet, preventing, slowing, and reversing the adverse effects of cognitive aging remains a challenge.

Heavy Alcohol Use and Age Effects on HIV-Associated Neurocognitive Function

BACKGROUND

There is growing concern about the health impact of heavy alcohol use in people infected with human immunodeficiency virus (HIV+). Mixed findings of past studies regarding the cognitive impact of alcohol use in HIV+ adults have been mixed, with inconsistent evidence that alcohol consumption exacerbates HIV-associated brain dysfunction. This study examined contributions of current heavy drinking, lifetime alcohol use disorder (AUD), and age to cognitive deficits in HIV+ adults, and relative to other HIV-associated clinical factors.

METHODS

Cognitive performance of HIV+ adults (n = 104) was assessed, and comparisons were made between heavy current to nonheavy drinkers (NIAAA criteria), lifetime AUD versus no-AUD, and older (>50 years) versus younger participants. Hierarchical regression analyses were conducted to examine the association between cognitive performance and current heavy drinking, lifetime AUD, and older age, while also correcting for HIV clinical factors and history of other substance use.

RESULTS

Individuals reporting current heavy drinking and meeting criteria for lifetime AUD demonstrated the greatest degree of deficits across multiple cognitive domains. Deficits were greatest among HIV+ adults with lifetime AUD, and older age was also associated with weaker cognitive performance. Lifetime AUD and older age independently exhibited stronger associations with cognitive performance than HIV clinical factors (e.g., viral load, current CD4, and nadir CD4) or past opiate and cocaine use.

CONCLUSIONS

Current heavy drinking and lifetime AUD adversely affect cognitive function in HIV+ adults. Greatest deficits existed when there was a history of AUD and continued current heavy drinking, indicating that past AUD continues to have an adverse impact and should not be ignored. That alcohol use was more strongly associated with cognitive performance than HIV clinical factors underscore clinical importance of targeting reduction in heavy alcohol consumption in HIV+ adults.

Educational Attainment Moderates the Association Between Hippocampal Volumes and Memory Performances in Healthy Older Adults

Objective: To examine whether educational attainment, as a proxy of cognitive reserve, moderated the association between hippocampal volumes and episodic verbal memory performances in healthy older adults.

Methods: Data from 76 community dwelling older adults were included in the present study. Measures of hippocampal volumes (total, left, and right) were obtained using FreeSurfer software. Immediate and delayed verbal recall scores were derived from performances on the California Verbal Learning Test-Second Edition and the Wechsler Memory Scale- Third Edition. Educational attainment was defined by years of education. Linear regression analyses were performed using immediate and delayed recall as dependent variables and hippocampal volumes, years of education, and their interaction terms as independent variables. All analyses were controlled for age, sex, depression, and health status.

Results: Total and left Hippocampal volumes had a positive main effect on delayed recall only. Additionally, the interaction between total, left, and right hippocampal volumes and education was a significant predictor for delayed recall performance but not for immediate recall performance. The positive association between hippocampal volumes and delayed recall was greatest in those with more years of education.

Conclusion: Larger hippocampal volumes were associated with better delayed verbal recall and the effect on delayed recall was greatest in those with more years of education. Having higher levels of education, or cognitive reserve, may enable individuals to capitalize on greater structural integrity in the hippocampus to support delayed recall in old age. However, longitudinal research is needed to investigate the directionality of these associations.

Task-Based Cognitive Fatigability for Older Adults and Validation of Mental Fatigability Subscore of Pittsburgh Fatigability Scale

Cognitive fatigue and cognitive fatigability are distinct constructs. Cognitive fatigue reflects perception of cognitive fatigue outside of the context of activity level and duration and can be reliably assessed via established instruments such as the Fatigue Severity Scale (FSS) and the Modified Fatigue Impact Scale (MFIS). In contrast, cognitive fatigability reflects change in fatigue levels quantified within the context of the level and duration of cognitive activity, and currently there are no reliable measures of cognitive fatigability. A recently published scale, the Pittsburgh Fatigability Scale (PFS), attempts to remedy this problem with a focus on the aged population. While the physical fatigability subscore of PFS has been validated using physical activity derived measures, the mental fatigability subscore of PFS remains to be tested against equivalent measures derived from cognitive activities. To this end, we recruited 35 older, healthy adult participants (mean age 73.77 ± 5.9) to complete the PFS as well as a prolonged continuous performance of a Stroop task (>2 h). Task-based assessments included time-on-task changes in self-reported fatigue scores (every 20 min), reaction time, and pupil diameter. Defining subjective fatigability, behavioral fatigability, and physiologic/autonomic fatigability to be the slope of change over time-on-task in the above three assessed variables, we found that the PFS mental subscore was not correlated with any of the three task-based fatigability measures. Instead, the PFS mental subscore was correlated with trait level fatigue measures FSS (ρ = 0.63, p < 0.001), and MFIS cognitive subsection (ρ = 0.36, p = 0.03). This finding suggested that the PFS mental fatigability subscore may not be an adequate measure of how fatigued one becomes after a given amount of mental work. Further development efforts are needed to create a self-report scale that reliably captures cognitive fatigability in older adults.

The Impact of Alcohol Use on Frontal White Matter in HIV

BACKGROUND

Alcohol use disorder (AUD) is prevalent among individuals diagnosed with human immunodeficiency virus (HIV), and both HIV and alcohol use have been shown to negatively affect the integrity of white matter pathways in the brain. Behavioral, functional, and anatomical impairments have been linked independently to HIV and alcohol use, and these impairments have bases in specific frontally mediated pathways within the brain.

METHODS

Magnetic resonance imaging data were acquired for 37 HIV+ participants without dementia or hepatitis C. Imaging data were processed through the FreeSurfer and TraCULA pipelines to obtain 4 bilateral frontal white matter tracts for each participant. Diffusion metrics of white matter integrity along the highest probability pathway for each tract were analyzed with respect to demographics, disease-specific variables, and reported substance use.

RESULTS

Significantly increased axial diffusivity (decreased axonal integrity) and a trending increase in mean diffusivity were observed along the anterior thalamic radiation (ATR) in participants with a history of AUD. A diagnosis of AUD explained over 36% of the variance in diffusivity along the ATR overall when accounting for clinical variables including nadir CD4 and age-adjusted HIV infection length.

CONCLUSIONS

This study provides evidence of HIV-related associations between alcohol use and indicators of axonal integrity loss along the ATR, a frontal pathway involved in the inhibition of addictive or unwanted behaviors. Reduced axonal integrity of this pathway was greatest in HIV+ participants with an AUD, even when considering the effect of age-adjusted disease length and severity (nadir CD4). This finding implicates a potential biological mechanism linking reduced integrity of frontal white matter to the high prevalence of AUD in an HIV+ population without dementia or hepatitis C.

Asymmetrical distractibility of global and focal visuospatial attention during segmental and total compound line bisections

BACKGROUND/OBJECTIVES

Compound horizontal lines are composed of 2 segments of unequal length and width. Line bisection requires that the participants attend to the entire line (global attention). The longer segment often distracts participants, suggesting that attention directed to this segment (focal attention) disrupts the allocation of global attention. This study attempted to learn whether the allocation of focal attention to a line segment is distracted by global attention allocated to the entire line and whether there are right-left distraction asymmetries when allocating focal or global attention.

METHOD

Twenty-four healthy adults (12 > 65 years old) attempted to bisect horizontal lines composed of 2 segments of unequal length, with the larger segment placed to the right or left. They were also asked to bisect the longer segment of these lines.

RESULTS

When allocating focal attention to the larger segment, healthy participants were more distracted when the smaller segment was on the left than on the right. In contrast, when attempting to allocate global attention to the entire line, participants were more distracted when the larger segment was on the right side. There were no significant differences between older and younger participants.

CONCLUSIONS

The asymmetrical global distraction during segment bisection might be related to the right hemisphere's dominance in mediating global attention and allocating attention leftward. In contrast, the asymmetrical focal distraction during full-line bisection might be related to the left hemisphere's dominance in mediating focal attention and allocating attention toward the right. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Background distraction during vertical solid and character line bisections

Background-objectives: When vertical lines are positioned above or below the center of the page, line bisection deviates toward the center of the page, suggesting that the edges of the page distract the allocation of attention to the line. A letter-character line (LCL) bisection requires both global and focal attention, to identify the target letter closest to the line's center. If more focal and less global attention is allocated to a LCL, more global attentional resources may be available and inadvertently allocated to the page. Alternatively, if the allocation of focal attention to a LCL inhibits global attentional processing, there may be less distraction by the page.

METHOD

Twenty-four healthy adults (12 older) bisected vertical solid and character lines centered, or positioned closer to the top or bottom of the page.

RESULTS

There was no difference between bisection of solid and character lines centered on the page. Page-related deviations were greater with character lines than solid line bisections, and greater for lines positioned toward the top than the bottom of the page. With lines positioned toward the top, the older participants' attempted bisections were higher than those of the younger participants.

CONCLUSIONS

These results suggest that the allocation of focal attention increases global attentional distractibility and that global-background attentional distraction is greater when the vertical lines are placed in the upper part of the page. Older participants appeared to be less distracted when lines were placed toward the top of the page, but the reason for this age difference requires further research.

High early life stress and aberrant amygdala activity: risk factors for elevated neuropsychiatric symptoms in HIV+ adults

Relative to HIV-negative adults, HIV+ adults report elevated levels of early life stress (ELS). In non-HIV samples, high ELS has been linked to abnormalities in brain structure and function, as well as increased risk of neuropsychiatric symptoms. Yet, little is known about the neural effects of high ELS, and their relation to elevated neuropsychiatric symptoms, in HIV+ adults. Recent studies have revealed combined effects of HIV and high ELS on amygdala morphometry. Aberrant amygdala activity is prominently implicated in studies of neuropsychiatric symptomology in non-HIV samples. Hence, this preliminary study examined: 1) the combined effects of HIV and high ELS on amygdala activity, and 2) the relation between amygdala activity and neuropsychiatric symptoms in HIV+ adults. We included 28 HIV+ adults and 25 demographically-matched HIV-negative control (HC) adults. ELS exposure was quantified using a retrospective ELS questionnaire, which defined four groups: HIV+ Low-ELS (N = 15); HIV+ High-ELS (N = 13); HC Low-ELS (N = 16); and HC High-ELS (N = 9). Participants completed a battery of neuropsychiatric measures. BOLD fMRI assessed amygdala reactivity during explicit observation of fearful/angry faces. High-ELS participants demonstrated reduced levels of amygdala reactivity relative to Low-ELS participants. HIV+ High-ELS participants reported higher levels of neuropsychiatric symptoms than all other groups. In the HIV+ group, lower amygdala responses were associated with higher neuropsychiatric symptoms, particularly depression, anxiety, and alexithymia. Collectively, these results suggest that high ELS exposure is a significant risk factor for neuropsychiatric symptoms in HIV+ adults. Furthermore, our results implicate ELS-related abnormalities in amygdala activity in the etiology of neuropsychiatric symptoms in HIV+ adults.

Associations between oxytocin receptor gene (OXTR) methylation, plasma oxytocin, and attachment across adulthood

The neuropeptide oxytocin (OT) has been implicated in a wide range of affiliative processes. OT exerts its functions via OT receptors, which are encoded by the oxytocin receptor gene (OXTR). Epigenetic modification of OXTR through the process of DNA methylation has been associated with individual differences in behavioral phenotypes. Specifically, lower levels of OXTR methylation have been linked to better social and affective functioning. However, research on epigenetic mechanisms of OXTR is scarce in non-clinical populations, and even less is known about epigenetic variability across adulthood. The present study assessed methylation levels at OXTR CpG site -934 and plasma OT levels in 22 young (20-31 years, M = 23.6) and 34 older (63-80 years, M = 71.4) participants. Lower levels of OXTR methylation and higher plasma OT levels were associated with less self-reported attachment anxiety in young but not older participants, with largely independent contributions of OXTR methylation and plasma OT levels. In contrast, in the overall sample, lower levels of OXTR methylation were associated with higher self-reported attachment avoidance. Age analysis suggested that these results were largely driven by young adults. Plasma OT levels were unrelated to attachment avoidance. Taken together, these findings support the emerging notion in the literature that epigenetic properties of OXTR, in addition to endogenous OT levels, are related to adult attachment. Further, the age effects observed in the associations between OXTR methylation, plasma OT, and adult attachment emphasize the importance of adopting a developmental perspective when studying properties of the OT system and their relation to affiliative processes. Findings contribute to growing evidence suggesting that epigenetic modification of genes regulating OT pathways and endogenous OT levels are associated with the way people form and maintain intimate social relationships.