COMT Val158Met Polymorphism, Cardiometabolic Risk, and Nadir CD4 Synergistically Increase Risk of Neurocognitive Impairment in Men Living With HIV

Cigarette smoking is associated with reduced neuroinflammation and better cognitive control in people living with HIV

People living with HIV (HIV+) are roughly twice as likely to smoke cigarettes (Smok+) as the general population. With the advent of effective antiretroviral therapies, it is increasingly important to understand the effects of chronic HIV infection and cigarette smoking on brain function and cognition since HIV+ individuals have heightened neuroinflammation and cognitive deficits even with such therapies. Based on prior studies demonstrating that smoking reduces a marker for neuroinflammation in HIV- individuals, we hypothesized that HIV+/Smok+ individuals would have less neuroinflammation and better cognitive control than HIV+/Smok- individuals. Fifty-nine participants (HIV-/Smok- [n = 16], HIV-/Smok+ [n=14], HIV+/Smok- [n = 18], and HIV+/Smok+ [n = 11]) underwent baseline eligibility tests, positron emission tomography (PET) scanning to determine levels of a marker for neuroinflammation, and assessment of cognitive control with the reverse-translated 5-choice continuous performance test (5C-CPT), with smokers having smoked to satiety prior to testing. For the PET data, a significant effect of smoking status on whole brain (WB) standardized uptake value (SUV) was found between HIV+/Smok+ and HIV+/Smok- participants (due to 18.8% lower WB SUV in the HIV+/Smok+ group). HIV+/Smok- participants exhibited a mean 13.5% higher WB SUV than HIV-/Smok- participants. For the 5C-CPT, HIV+/Smok+ participants performed significantly better than HIV+/Smok- participants (d prime), and HIV+/Smok- participants performed worse than HIV-/Smok- participants. Thus, HIV+/Smok+ individuals demonstrated lower levels of the neuroinflammation marker and better cognitive control than HIV+/Smok- individuals. Given that HIV+ individuals whose HIV is well-controlled can still have chronic neurocognitive complications, study results suggest possible paths for future research into nicotine-related treatments to prevent such complications.

Cerebrospinal fluid profiles of targeted metabolomics on neurotransmitters in patients with post-neurosurgical bacterial meningitis

Background

Post-neurosurgical bacterial meningitis (PNBM) is a severe complication in patients receiving neurosurgical treatments. Pathogens and neuroinflammation have been reported to influence metabolites in the microenvironment of the central nervous system. However, information about the relationship between neurotransmitter levels and PNBM is still limited. In this study, we aimed to investigate the diagnostic potential of neurotransmitters for PNBM in the patients with stroke.

Methods

In this study, a total of 66 stroke patients were recruited. Among them, 40 patients were complicated with PNBM. We profiled cerebrospinal fluid (CSF) levels of neurotransmitter precursors and metabolites using the targeted metabolomics method, which contained 26 precursors and metabolites of neurotransmitters, using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC/MS).

Results

We found that 14 biomarkers were downregulated but 3,4-dihydroxyphenylacetic acid (DOPAC) was upregulated in the CSF of PNBM patients. Among the biomarkers, D-glutamine (AUC=1.000), Boc-D-Tyr-OH (AUC=0.9447), L(+)-arginine (AUC=0.9418), and DOPAC (AUC=0.9173) had strong diagnostic efficiency for PNBM. Bioinformatic analysis showed that tyrosine metabolism, butanoate metabolism, histidine metabolism, alanine, aspartate and glutamate metabolism, glycerophospholipid metabolism, arginine and proline metabolism, and tryptophan metabolism might be involved in the pathogenesis of PNBM. After reviewing previous studies, we found a probable diverse pathophysiological alteration between PNBM and community-acquired bacterial meningitis.

Conclusions

In summary, we identified downregulated levels of D-glutamine, Boc-D-Tyr-OH, L(+)-arginine, and phenprobamate, and an upregulated level of DOPAC in CSF to have strong diagnostic efficiencies. The results also offered potential targets for the treatment of PNBM.

Human Immunodeficiency Virus as a Risk Factor for Cardiovascular Disease

The developments in HIV treatments have increased the life expectancy of people living with HIV (PLWH), a situation that makes cardiovascular disease (CVD) in that population as relevant as ever. PLWH are at increased risk of CVD, and our understanding of the underlying mechanisms is continually increasing. HIV infection is associated with elevated levels of multiple proinflammatory molecules, including IL-6, IL-1β, VCAM-1, ICAM-1, TNF-α, TGF-β, osteopontin, sCD14, hs-CRP, and D-dimer. Other currently examined mechanisms include CD4 + lymphocyte depletion, increased intestinal permeability, microbial translocation, and altered cholesterol metabolism. Antiretroviral therapy (ART) leads to decreases in the concentrations of the majority of proinflammatory molecules, although most remain higher than in the general population. Moreover, adverse effects of ART also play an important role in increased CVD risk, especially in the era of rapid advancement of new therapeutical options. Nevertheless, it is currently believed that HIV plays a more significant role in the development of metabolic syndromes than treatment-associated factors. PLWH being more prone to develop CVD is also due to the higher prevalence of smoking and chronic coinfections with viruses such as HCV and HBV. For these reasons, it is crucial to consider HIV a possible causal factor in CVD occurrence, especially among young patients or individuals without common CVD risk factors.

Childhood trauma and genetic variation in the DAT 40-bp VNTR contribute to HIV-associated neurocognitive disorders

HIV/AIDS is a major public health burden in South Africa, currently affecting an estimated 13.5% of the population. Despite improved access to antiretroviral therapies, HIV-associated neurocognitive disorders (HAND), characterised by a spectrum of neurocognitive impairment, emotional disturbances and motor abnormalities, continue to persist. Gene-environment interactions contribute to HAND pathophysiology and previous research has identified childhood trauma as an environmental risk factor. Dopaminergic signalling in the prefrontal cortex plays a key role in cognitive function. Thus, variants in genes encoding the dopamine transporter (DAT) and catechol-O-methyltransferase (COMT), which are responsible for dopamine transport and metabolism, could represent genetic risk factors for HAND. This study investigated whether the DAT variable number of tandem repeats (VNTR) and COMT Val158Met (rs4680) polymorphisms are associated with longitudinal change in cognitive function in the context of childhood trauma and HIV. Participants (n = 49 HIV-negative and n = 64 HIV-positive women) completed the Childhood Trauma Questionnaire - Short Form (CTQ-SF) and provided blood for genetic analyses. Global cognitive scores were generated from baseline and one-year follow-up assessments. Following polymerase chain reaction, genotypes were determined using gel electrophoresis and confirmed by Sanger sequencing. Baseline global cognitive scores, genotype, HIV status and CTQ-SF scores were regressed on one-year global cognitive scores in regression models. Analysis of variance was used to examine the effect of including predictor variable interactions on model fit. HIV seropositivity was associated with poorer cognitive performance at one-year follow-up (p = 2.46 ×10-4). The combination of HIV and DAT 10-repeat homozygosity (DAT 10/10) was associated with reduced global cognitive scores in longitudinal models (p = 0.010). Including the interaction between DAT 10/10, childhood trauma, and HIV explained significantly more of the variance in longitudinal cognitive scores (p = 0.008). There were no significant associations with the COMT genotype. Our research indicates that childhood trauma and genetic variation in DAT contribute toward the aetiology of HAND. Future studies in larger cohorts are warranted to verify these results.

Lower CSF homovanillic acid relates to higher burden of neuroinflammation and depression in people with HIV disease

BACKGROUND

HIV-related neuroinflammation has been proposed as a catalyst for dopaminergic dysregulation in mesocortical pathways, which may contribute to the pathogenesis of depression. Abnormalities in dopaminergic neurotransmission and depression are common in people with HIV (PWH), however the link between dopamine (DA) and depression in PWH is poorly characterized. This study investigated CSF dopaminergic biomarkers, specifically DA and its metabolite, homovanillic acid (HVA), and examined their relationship with depressive symptoms and CSF neuroinflammatory markers in PWH and HIV-seronegative (HIV-) individuals.

METHODS

Participants were 102 HIV- individuals and 123 PWH (mean age = 42) who underwent neuropsychiatric evaluations and lumbar puncture. Current depression severity was classified using the Beck Depression Inventory-II (BDI-II). CSF was assayed for DA and HVA using high performance liquid chromatography and neuroinflammatory markers using immunoassays. Linear regressions modelled BDI-II scores as a function of HIV, dopaminergic biomarker z-scores, and their interaction, controlling for psychosocial factors. Correlational analyses examined dopaminergic and neuroinflammatory relationships.

RESULTS

PWH had significantly higher BDI-II scores than HIV- participants. DA and HVA were not associated with HIV status but both significantly moderated the effect of HIV on BDI-II scores, such that PWH exhibited higher depressive symptoms than HIV- participants only at lower concentrations of HVA (z ≤ 0.06) and DA (z ≤ 0.11). In PWH only, lower HVA significantly correlated with higher BDI-II scores and higher neuroinflammation, including higher MCP-1 and IP-10.

CONCLUSIONS

Results suggest that the pathophysiology of depression in PWH differs from that in HIV- individuals. Specifically, lower central dopaminergic activity was selectively associated with greater depressive symptoms and neuroinflammation in PWH. With the rise in consideration of DA agonists for the treatment of depression, these results suggest that PWH may show a greater response to these agents than their HIV- peers.

Cerebrospinal Fluid Norepinephrine and Neurocognition in HIV and Methamphetamine Dependence

OBJECTIVE

HIV disease and methamphetamine (METH) dependence share overlapping mechanisms of neurotoxicity that preferentially compromise monoamine-rich frontostriatal circuitry. However, norepinephrine (NE) function is poorly understood in HIV and METH dependence. We evaluated associations between cerebrospinal fluid (CSF) NE and HIV, METH dependence, and neurocognition.

METHODS

Participants included 125 adults, stratified by HIV serostatus (HIV+/HIV-) and recent METH dependence (METH+/METH-), who underwent comprehensive neurocognitive testing and lumbar puncture. CSF NE was assayed using high-performance liquid chromatography. Multivariable regression modelled NE as a function of HIV, METH, and their interaction, adjusting for demographic and clinical factors. Pearson correlations examined relationships between NE and demographically-adjusted neurocognitive domain scores.

RESULTS

HIV significantly interacted with METH (P < 0.001) such that compared with HIV-/METH-, CSF NE was markedly elevated in the single risk-groups (HIV+/METH-: d = 0.96; HIV-/METH+: d = 0.79) and modestly elevated in the dual-risk group (HIV+/METH+: d = 0.48). This interaction remained significant after adjustment for lifetime depression, antidepressant use, and race/ethnicity. In the full sample, higher NE levels significantly correlated with worse global function (r = -0.19), learning (r = -0.23), and delayed recall (r = -0.18). Similar relationships between higher NE and worse neurocognition were detected in the METH- groups (ie, HIV-/METH- and HIV+/METH-) and in the virally-suppressed persons HIV+ subgroup, but not in the METH+ groups (ie, HIV-/METH+, HIV+/METH+).

DISCUSSION

HIV and METH independently, but not additively, relate to noradrenergic excess in the central nervous system, and perturbations to noradrenergic function may represent a pathophysiological mechanism of HIV-related neurocognitive dysfunction. Consistent with prior reports that noradrenergic excess compromises hippocampal and prefrontal function, higher NE related to worse neurocognition, even among successfully treated persons with HIV. Pharmacological and psychosocial interventions that stabilize NE function may improve neurocognition in persons with HIV.

COMT val158met genotype alters the effects of methamphetamine dependence on dopamine and dopamine-related executive function: preliminary findings

The Met-allele of the COMT Val158Met polymorphism slows metabolism and increases bioavailability of dopamine (DA) in the prefrontal cortex compared to the Val-allele. Healthy Met-carriers outperform Val-carriers on executive function (EF) tests, yet this 'advantage' disappears in methamphetamine (METH) dependence. Met-carriers may be disproportionately vulnerable to METH-related perturbations of DA, yet it is unknown whether COMT modulates METH effects on CSF DA biomarkers. Participants were 75 METH+ and 47 METH- men who underwent neurocognitive testing, COMT genotyping, and lumbar puncture. CSF was assayed for DA and its metabolite, homovanillic acid (HVA). Separate linear models regressed DA, HVA, and HVA/DA ratios on COMT, METH and their interaction. Pearson correlations examined associations between DA and EF. Significant interactions indicated that METH+ had lower DA and higher HVA/DA ratios among Met/Met, but not Val/Met-or Val/Val. Met/Met-exhibited the highest DA levels among METH-, whereas DA levels were comparable between Met/Met-and Val-carriers among METH+. Higher DA correlated with better EF in METH- Met/Met, but did not predict EF in the entire sample. DA was expectedly higher in METH- Met/Met, yet a discordant genotype-phenotype profile emerged in METH+ Met/Met, consistent with the notion that slow DA clearance exacerbates METH-associated DA dysregulation.

The Effects of Low-Risk Drinking on Neurocognition Among Older Persons Living With HIV as Compared to Those Without HIV

BACKGROUND

Heavy alcohol use negatively impacts neurocognition, but some studies report neurocognitive benefits associated with light drinking among HIV-seronegative (HIV-) older persons, suggesting a nonlinear or an inverted "J-shaped" association of alcohol consumption on neurocognition. Alcohol use is common among people with HIV (PWH); however, the association between recent "low-risk" alcohol consumption and neurocognition among PWH is poorly understood.

METHODS

Participants included 310 PWH and 89 HIV- older (≥50 years) adults who reported alcohol abstinence or "low-risk" drinking, defined per the National Institute on Alcohol Abuse and Alcoholism criteria (i.e., ≥15 drinks/wk or ≥5 drinks/d for men; ≥8 drinks/wk or ≥4 drinks/d for women). Neurocognition was measured using global and domain-specific demographically corrected T-scores. Multiple linear regressions examined the interaction between total drinks in the last 30 days (linear and quadratic terms) and HIV serostatus on neurocognition, covarying for age, sex, lifetime major depressive disorder, lifetime nonalcohol substance use disorders, and lifetime alcohol use disorder.

RESULTS

Total drinks consumed in the last 30 days did not differ by HIV serostatus (p = 0.202). Among HIV- older adults, quadratic effects of total drinks on neurocognition occurred such that optimal neurocognition (i.e., global function, executive function, learning, delayed recall, and motor skills) was detected at intermediate levels of "low-risk" drinking (~20 to 40 drinks), with poorer performance at the lower and higher ranges of "low-risk" consumption. In PWH, total drinks did not exhibit linear or quadratic associations with neurocognition.

CONCLUSIONS

In HIV- "low-risk" drinkers, intermediate levels of recent alcohol use were associated with better neurocognition, consistent with the inverted J-shaped association. The same nonlinear effect of recent alcohol consumption on neurocognition was absent in PWH, indicating there may be no beneficial or deleterious effects of low-risk alcohol consumption on neurocognition among PWH. Future research is warranted to examine associations between alcohol consumption and HIV-related biopsychosocial disadvantages that may supersede the neurocognitive benefits of alcohol.

Genetic variation in alcohol dehydrogenase is associated with neurocognition in men with HIV and history of alcohol use disorder: preliminary findings

The co-occurrence of HIV and alcohol use disorder (AUD) amplifies risk for neural injury and neurocognitive deficits. However, the substantial neurocognitive heterogeneity across HIV+/AUD+ individuals suggests inter-individual differences in vulnerability to the neurotoxicity of comorbid HIV/AUD. Genetic variation in alcohol dehydrogenase (ADH), which metabolizes ethanol, may contribute to inter-individual neurocognitive variability. We evaluated associations between five ADH single-nucleotide polymorphisms (SNPs) and neurocognition in men stratified by HIV and lifetime AUD status. Neurobehavioral assessments were administered to 153 men. Three-way ANOVAs examined the interaction of HIV, AUD, and ADH SNPs on global and domain-specific demographically corrected T scores. Follow-up ANCOVAs adjusted for age, estimated verbal IQ, depression, and remote non-alcohol substance use disorders. HIV/AUD groups differed globally and for verbal fluency, working memory, executive function, and processing speed T scores specifically, with HIV+/AUD+ exhibiting the poorest performance. ADH4 (rs1126671) was associated with large effects on working memory (d = - 1.16, p = .001) and executive function (d = - 0.77, p = .028) selectively in HIV+/AUD+, which remained significant in ANCOVA models. ADH1A (rs3819197) moderated the deleterious effects of HIV+/AUD+ on processing speed such that HIV+/AUD+ related to slower information processing in A allele carriers but not GG homozygotes (ps < 0.03). Preliminary findings suggest genetic variation in the ADH pathway moderates the deleterious neurocognitive effects of comorbid HIV/AUD. Differential metabolism of heavy ethanol exposure may compromise neurocognition under conditions of neurobiological stress, such as in HIV infection. The functional effects on ethanol metabolism of ADH SNPs examined in this study remain poorly understood, warranting further examination of pharmacokinetic mechanisms mediating ADH gene-neurobehavior relationships in HIV.

Comorbid HIV infection and alcohol use disorders: Converging glutamatergic and dopaminergic mechanisms underlying neurocognitive dysfunction

Alcohol use disorders (AUDs) are highly comorbid with human immunodeficiency virus (HIV) infection, occurring at nearly twice the rate in HIV positive individuals as in the general population. Individuals with HIV who consume alcohol show worse long-term prognoses and may be at elevated risk for the development of HIV-associated neurocognitive disorders. The direction of this relationship is unclear, and likely multifactorial. Chronic alcohol exposure and HIV infection independently promote cognitive dysfunction and further may interact to exacerbate neurocognitive deficits through effects on common targets, including corticostriatal glutamate and dopamine neurotransmission. Additionally, drug and alcohol use is likely to reduce treatment adherence, potentially resulting in accelerated disease progression and subsequent neurocognitive impairment. The development of neurocognitive impairments may further reduce cognitive control over behavior, resulting in escalating alcohol use. This review will examine the complex relationship between HIV infection and alcohol use, highlighting impacts on dopamine and glutamate systems by which alcohol use and HIV act independently and in tandem to alter corticostriatal circuit structure and function to dysregulate cognitive function.