Periodontitis is associated with altered brain structure and function in normal cognition middle-aged and elderly individuals

BACKGROUND

Numerous studies have proposed that periodontitis is a potential risk factor for Alzheimer's disease. However, the association between periodontitis and brain normal cognition in aged and elderly individuals (NCs) is unclear. Such a link could provide clues to Alzheimer's disease development and strategies for early prevention.

OBJECTIVE

To explore the associations between periodontal condition and metrics of both brain structure and function among NCs with the help of multimodal magnetic resonance imaging (MRI).

METHODS

High-resolution T1-weighted structural data, resting-state functional-MRI data, and measures of periodontal condition were collected from 40 NCs. Cortical volume, thickness, and area as well as regional homogeneity were calculated with the aid of DPABISurf software. Correlation analyses were then conducted between each imaging metric and periodontal index.

RESULTS

Consistent negative correlations were observed between severity of periodontitis (mild, moderate, severe) and cortical volume, area, and thickness, not only in brain regions that took charge of primary function but also in brain regions associated with advanced cognition behavior. Among participants with mild attachment loss (AL) and a shallow periodontal pocket depth (PPD), periodontal index was positively correlated with most measures of brain structure and function, while among participants with severe AL and deep PPD, periodontal index was negatively correlated with measures of brain structure and function (all p < .005 for each hemisphere).

CONCLUSIONS

Our results demonstrate that periodontitis is associated with widespread changes in brain structure and function among middle-aged and elderly adults without signs of cognitive decline, which might be a potential risk factor for brain damage.

Associations of potential ADRD plasma biomarkers in cognitively normal volunteers

INTRODUCTION

This study examined the relationships between 13 novel blood-plasma biomarkers and dementia-related demographic and health factors in a cohort of 237 cognitively normal research volunteers whose average age was ≈82 years and who were 63% female.

METHODS

We regressed each biomarker on selected covariates to explore the associations between the biomarkers and selected factors to assess whether they may contribute to biomarker values. Post hoc sensitivity analyses were done with updated data and consistent variable sets for robustness and batch effects.

RESULTS

Biomarker concentrations were largely not associated with demographics or health conditions, but some expected associations (e.g., apolipoprotein E [APOE] status with amyloid beta [Aβ]42/Aβ40) were observed. Post hoc results remained similar to those of the main analysis.

DISCUSSION

The absence of strong associations between the biomarkers with age, gender, or medical conditions suggests that changes in these biomarkers, when observed, may be attributable to neuropathological changes.

HIGHLIGHTS

Among N = 237 cognitively normal adults, we studied candidate Alzheimer's disease and related dementia (ADRD) plasma biomarkers. Biomarkers were largely not associated with demographic or health factors. Apolipoprotein E (APOE) status was associated with amyloid beta (Aβ)42/Aβ40 ratio. These results support hypotheses that plasma biomarkers are informative for ADRD.

Cure of Alzheimer's Dementia in Many Patients by Using Intranasal Insulin to Augment an Inadequate Counter-Reaction, Edaravone to Scavenge ROS, and 1 or 2 Other Drugs to Address Affected Brain Cells

The goal of treatment for Alzheimer's dementia (AD) is the restoration of normal cognition. No drug regimen has ever achieved this. This article suggests that curing AD may be achieved by combination therapy as follows. First, with intranasal insulin to augment the body's natural counter-reaction to the changes in brain cell-types that produced the dementia. Second, with edaravone to decrease free radicals, which are increased and causal in AD. Third, as described elsewhere, with one or two drugs from among pioglitazone, fluoxetine, and lithium, which address the brain cell-types whose changed functions cause the dementia. Insulin restores cerebral glucose, which is the main nutrient for brain neurons whose depletion is responsible for the dementia; and edaravone decreases ROS, which are intrinsic causes of neuropathology in AD. This combination of drugs is a potential cure for many patients with AD, and should be tested in a clinical trial.

Retinal Vascular Changes in Alzheimer's Dementia and Mild Cognitive Impairment: A Pilot Study Using Ultra-Widefield Imaging

Purpose

Retinal microvascular abnormalities measured on retinal images are a potential source of prognostic biomarkers of vascular changes in the neurodegenerating brain. We assessed the presence of these abnormalities in Alzheimer's dementia and mild cognitive impairment (MCI) using ultra-widefield (UWF) retinal imaging.

Methods

UWF images from 103 participants (28 with Alzheimer's dementia, 30 with MCI, and 45 with normal cognition) underwent analysis to quantify measures of retinal vascular branching complexity, width, and tortuosity.

Results

Participants with Alzheimer's dementia displayed increased vessel branching in the midperipheral retina and increased arteriolar thinning. Participants with MCI displayed increased rates of arteriolar and venular thinning and a trend for decreased vessel branching.

Conclusions

Statistically significant differences in the retinal vasculature in peripheral regions of the retina were observed among the distinct cognitive stages. However, larger studies are required to establish the clinical importance of our findings. UWF imaging may be a promising modality to assess a larger view of the retinal vasculature to uncover retinal changes in Alzheimer's disease.

Translational Relevance

This pilot work reports an investigation into which retinal vasculature measurements may be useful surrogate measures of cognitive decline, as well as technical developments (e.g., measurement standardization), that are first required to establish their recommended use and translational potential.

Predictive Utility of Plasma Amyloid and Tau for Cognitive Decline in Cognitively Normal Adults

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disease affecting mostly elderly adults. Recent diagnostic criteria for AD recommend the use of imaging and/or cerebrospinal fluid (CSF) biomarkers together with clinical presentation for a more persuasive diagnosis. The invasiveness and expense of such examinations have led to the search for blood-based biomarkers. The plasma levels of amyloid-β (Aβ) protein and tau peptides have been found to correlate with CSF levels and imaging findings in patients with AD. This study was conducted to explore the predictive utility of plasma Aβ1-42 and total tau (t-tau) levels for cognitive decline in healthy adults.

METHODS

In this prospective longitudinal study, we enrolled adults aged ≥ 50 years with normal cognition at Taipei Veterans General Hospital from November 2016 to April 2019. Blood samples were collected on recruitment, and plasma Aβ1-42 and t-tau levels were quantified through immunomagnetic reduction. Thorough neurophysiological assessment was performed at baseline and at the annual follow-up visit. The participants were divided into two groups according to cognitive decline. The predictive utility of Aβ1-42 and t-tau levels was evaluated by receiver operating characteristic curve analysis.

RESULTS

Of 60 participants recruited, seven participants progressed to mild cognitive impairment and 53 retained normal cognition on follow-up (average 1.07 ± 0.2 years). The baseline levels of plasma biomarkers (Aβ1-42, t-tau, and Aβ1-42 × t-tau) were significantly higher in the progressive than in the stable group (p = 0.005, p = 0.007, and p = 0.005, respectively). Higher plasma biomarker levels (Aβ1-42 ≥ 16.96 pg/ml and Aβ1-42 × t-tau ≥ 382 pg2/ml2) predicted more cognitive decline on annual follow-up visits.

CONCLUSION

Plasma Aβ1-42 and t-tau levels have predictive utility for cognitive decline, even in subjects with normal cognition. Higher baseline plasma Aβ1-42 and t-tau levels may indicate a higher risk of cognitive decline in cognitively normal adults.

Assessment of High Risk for Alzheimer's Disease Using Plasma Biomarkers in Subjects with Normal Cognition in Taiwan: A Preliminary Study

Background

In Alzheimer's disease (AD), cognitive impairment begins 10-15 years later than neurodegeneration in the brain. Plasma biomarkers are promising candidates for assessing neurodegeneration in people with normal cognition. It has been reported that subjects with the concentration of plasma amyloid-β 1-42×total tau protein higher than 455 pg²/ml² are assessed as having a high risk of amnesic mild impairment or AD, denoted as high risk of AD (HRAD).

Objective

The prevalence of high-risk for dementia in cognitively normal controls is explored by assaying plasma biomarkers.

Methods

422 subjects with normal cognition were enrolled around Taiwan. Plasma Aβ_1-40, Aβ_1-42, and T-Tau levels were assayed using immunomagnetic reduction to assess the risk of dementia.

Results

The results showed that 4.6% of young adults (age: 20-44 years), 8.5% of middle-aged adults (age: 45-64 years), and 7.3% of elderly adults (age: 65-90 years) had HRAD. The percentage of individuals with HRAD dramatically increased in middle-aged and elderly adults compared to young adults.

Conclusion

The percentage of HRAD in cognitively normal subjects are approximately 10%, which reveals that the potentially public-health problem of AD in normal population. Although the subject having abnormal levels of Aβ or tau is not definitely going on to develop cognitive declines or AD, the risk of suffering cognitive impairment in future is relatively high. Suitable managements are suggested for these high-risk cognitively normal population. Worth noting, attention should be paid to preventing cognitive impairment due to AD, not only in elderly adults but also middle-aged adults.

Operational Determination of Subjective Cognitive Decline, Mild Cognitive Impairment, and Dementia Using Sum of Boxes of the Clinical Dementia Rating Scale

Objectives: The Clinical Dementia Rating (CDR) Scale is the gold standard for the staging of dementia due to Alzheimer's disease (AD). However, the application of CDR for the staging of subjective cognitive decline (SCD) and mild cognitive impairment (MCI) in AD remains controversial. This study aimed to use the sum of boxes of the CDR (CDR-SB) plus an SCD single questionnaire to operationally determine the different stages of cognitive impairment (CI) due to AD and non-AD. Methods: This was a two-phase study, and we retrospectively analyzed the Show Chwan Dementia registry database using the data selected from 2015 to 2020. Individuals with normal cognition (NC), SCD, MCI, and mild dementia (MD) due to AD or non-AD with a CDR < 2 were included in the analysis. Results: A total of 6,946 individuals were studied, including 875, 1,009, 1,585, and 3,447 with NC, SCD, MCI, and MD, respectively. The cutoff scores of CDR-SB for NC/SCD, SCD/MCI, and MCI/dementia were 0/0.5, 0.5/1.0, and 2.5/3.0, respectively. The receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) values of the test groups were 0.85, 0.90, and 0.92 for discriminating NC from SCD, SCD from MCI, and MCI from dementia, respectively. Compared with the Cognitive Abilities Screening Instrument or the Montreal Cognitive Assessment, the use of CDR-SB is less influenced by age and education. Conclusion: Our study showed that the operational determination of SCD, MCI, and dementia using the CDR-SB is practical and can be applied in clinical settings and research on CI or dementia.

Transition from mild cognitive impairment to normal cognition: Determining the predictors of reversion with multi-state Markov models

INTRODUCTION

The theoretical framework of the Alzheimer's disease continuum considers transition between stages in a unidirectional manner. Here we examine the rate of reversion from mild cognitive impairment (MCI) to normal cognition (NC) and explore a set of potential variables associated with this phenomenon.

METHODS

A total of 985 Spanish community-dwelling individuals aged 70 years and over at baseline were monitored for 5 years. During this time, 173 MCI and 36 dementia cases were identified. Multi-state Markov models were performed to characterize transitions between states through the dementia continuum.

RESULTS

The rate of reversion from MCI to NC was 11%. There were significant non-modifiable (age, socioeconomic status, or apolipoprotein E) and modifiable factors (cognitive training or absence of affective symptoms) associated with reversion.

DISCUSSION

Overall, our results highlight that the likelihood of progression from MCI to dementia is very similar to that of reversion from MCI to NC.

Relationship of Neurofilament Light (NfL) and Cognitive Performance in a Sample of Mexican Americans with Normal Cognition, Mild Cognitive Impairment and Dementia

INTRODUCTION

This study characterized the relationship between plasma NfL and cognition in a community-based sample of older Mexican Americans.

METHODS

544 participants completed a battery of neuropsychological tests and were diagnosed using clinical criteria. NfL was assayed using Simoa. NfL levels across groups and tests were analyzed.

RESULTS

Difference in NfL was found between normal and impaired groups and was related to global cognition, processing speed, executive functions and a list of learning tasks with a significant negative effect for all diagnostic groups. NfL had a negative impact on processing speed, attention, executive functions and delayed and recognition memory for both normal and MCI groups.

CONCLUSION

The research supports plasma NfL as a marker of cognitive impairment related to neurodegenerative processes in Mexican Americans and may be a marker of early changes in cognition in those with normal cognition and at risk for developing MCI.

A vaccine to prevent initial loss of cognition and eventual Alzheimer's disease in elderly persons

Prevention is better than cure and prevention of Alzheimer's disease (AD) may be possible. In elderly persons who are cognitively normal, synaptic hypometabolism as shown by reduced cerebral uptake of fluorodeoxyglucose (18F-FDG), provides a premonitory signal of potential, future loss of cognition if those individuals also have present evidence of amyloid deposition seen in the Pittsburgh compound B positron emission tomography (PIB-PET) scan for amyloid. Those are the persons who should be targeted if one aims to prevent AD. The synaptic hypometabolism implies that the brain's availability of adenosine triphosphate (ATP) is inadequate for performance of all required synaptic functions. This review first describes the basis for asserting that reduced cerebral uptake of 18F-FDG accurately reflects synaptic hypometabolism; second, explains the basis for asserting that hypometabolism implies inadequate ATP; third, shows that amyloid beta (Aβ) itself, Aβ modified by pyroglutamate to become a molecule termed pE(3)Aβ, and cyclophilin-D, in concert are the main contributors to inadequate synaptic ATP and that, therefore, reducing all of their levels would neutralize their combined effect and correct the hypometabolism. pE(3)Aβ is more neurotoxic than unmodified Aβ; and cyclophilin D inhibits ATP synthase and reduces ATP formation. Finally, this review describes an mRNA self-replicating vaccine that will raise brain levels of ATP by reducing Aβ, pyroglutamate-modified Aβ, and cyclophilin-D, and thereby-in cognitively normal elderly persons who have synaptic hypometabolism-prevent initiation of the process that terminates in AD.

Osteoarthritis Was Associated With a Faster Decline in Hippocampal Volumes in Cognitively Normal Older People

OBJECTIVE

To examine whether osteoarthritis (OA) is associated with a change in adjusted hippocampal volumes (HpVR: hippocampal/intracranial volume × 103) over time among cognitively normal older people.

METHODS

We examined the cross-sectional and longitudinal associations of OA with HpVR among individuals with normal cognition (NC) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. At baseline, a total of 372 individuals with NC were included.

RESULTS

In the cross-sectional analyses of baseline data, we did not find a significant relationship between OA and HpVR among individuals with NC. However, in the longitudinal analyses, OA was significantly associated with change in HpVR over time among individuals with NC. Specifically, compared with individuals without OA, those with OA showed a faster decline in HpVR over time when controlling for other potential confounders, including age, educational attainment, gender, and APOE4 genotype.

CONCLUSION

OA status was significantly associated with a change in HpVR over time among individuals with NC.

Factors for predicting reversion from mild cognitive impairment to normal cognition: A meta-analysis

OBJECTIVE

Subjects with mild cognitive impairment (MCI) may revert to normal cognition (NC), but predictive factors are under study. We therefore sought to identify factors which could help in predicting reversion from MCI to NC.

METHODS

Relevant studies were retrieved from PubMed, EMBASE, Cochrane Library, MEDLINE, Web of Science, EBSCO, and OVID. According to the inclusion and exclusion criteria, high-quality assessments of relevant literatures were conducted, followed by data extraction and meta-analysis with Stata 12.0 software.

RESULTS

A total of 17 studies with 6829 participants were included in the meta-analysis. The overall reversion rate is 27.57%. Positive predictive factors were found in younger age (SMD = -0.345, 95% CI, -0.501 to -0.189), higher education level (SMD = 0.337, 95% CI, 0.117-0.558), no APOE ε4 allele (OR = 0.728, 95% CI, 0.575-0.922), no hypertension (OR = 0.826, 95% CI, 0.692-0.987), no stroke (OR = 0.696, 95% CI, 0.507-0.953), and higher Mini-Mental State Examination (MMSE) score (SMD = 0.707, 95% CI, 0.461-0.953).

CONCLUSION

Individuals who are at young age, have higher education level and MMSE score, and have no APOEe4 allele, no hypertension, and no stroke had a high probability to revert from MCI to NC.

Risk factors for predicting progression from normal cognition to mild cognitive impairment: protocol for a systematic review and meta-analysis of cohort studies

INTRODUCTION

Mild cognitive impairment (MCI) often represents the earliest stage of Alzheimer's disease. There has been considerable research investigating specific risk factors regarding the progression from normal cognition to MCI. However, different studies have come to different conclusions on the impact of particular risk factors. Therefore, it is necessary to conduct a meta-analysis of the risk factors that predict cognitive disruption in individuals based on associations with MCI.

METHODS AND ANALYSIS

We will search seven electronic databases without time limit, including MEDLINE, EMBASE, The Cochrane Library, Web of Science, China National Knowledge Infrastructure, the Wan Fang Database and China Biology Medicine. Two researchers will independently screen for eligibility and perform data extraction. Data were extracted from cohort studies meeting the inclusive criteria according to the Newcastle Ottawa Scale (NOS) methods. A third member of the research team will be contacted when a consensus cannot be reached. Any disagreement will be settled by consensus. The NOS will be used to assess the quality of the studies. All analyses were performed using Stata V.15.1.

ETHICS AND DISSEMINATION

We will report this review in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. We will disseminate our findings through a publication in a peer-reviewed journal. This systematic review does not require ethical approval as no primary data are collected.

PROSPERO REGISTRATION NUMBER

CRD42018109099.

Cognitive Impairment and its Association with Glycemic Control in Type 2 Diabetes Mellitus Patients

INTRODUCTION

Type 2 diabetes mellitus is one of the major causes of increasing morbidity worldwide. Effective screening is carried out routinely for diabetic retinopathy, neuropathy, and nephropathy. Of late, studies have reported that cognitive decline can occur in people with diabetes, which could go undetected for a long period, and hence routine screening could be warranted.

METHODOLOGY

Our objective was to study the prevalence of previously unknown mild cognitive impairment (MCI) in type 2 diabetic patients visiting a tertiary care center with the Montreal Cognitive Assessment (MoCA) test and to study the correlations of HbA1c, fasting blood sugar (FBS), postprandial blood sugar (PPBS), age, and duration of diabetes with the MoCA scores. Seventy patients with type 2 diabetes mellitus were included in the study. Patients with MoCA scores ≥26 were considered to have normal cognition (NC) and those with <26 MCI.

RESULTS

MCI was noted in 38 (54.29%) type 2 diabetes mellitus patients and NC in 32 (45.71%). Those with MCI had higher HbA1c (8.79 ± 1.85 vs. 7.78 ± 1.60), higher FBS (177.05 ± 62.48 vs. 149.38 ± 54.38), and PPBS (282.03 ± 85.61 vs. 214.50 ± 82.43), which were statistically significant. The cognitive domains of executive function, naming, attention, language, and memory showed a statistically significant difference between those with MCI and NC. There were no differences in the mean age, duration of diabetes, and educational status between the groups.

CONCLUSION

The high prevalence of MCI in type 2 diabetic patients highlights the importance of implementing routine cognitive testing. The correlation of cognitive impairment with poor glucose control needs further studies to find out whether improving glycemic control will help improve cognition.

The Effect of Traumatic Brain Injury History with Loss of Consciousness on Rate of Cognitive Decline Among Older Adults with Normal Cognition and Alzheimer's Disease Dementia

Traumatic brain injury (TBI) is thought to be a risk factor for dementia, including dementia due to Alzheimer's disease (AD). However, the influence of TBI history on the neuropsychological course of AD is unknown and, more broadly, the effect of TBI history on age-related cognitive change is poorly understood. We examined the relationship between history of TBI with loss of consciousness (LOC) history and cognitive change in participants with normal cognition and probable AD, stratified by APOEɛ4 allele status. The sample included 706 participants (432 with normal cognition; 274 probable AD) from the National Alzheimer's Coordinating Center (NACC) dataset that completed the Uniform Data Set evaluation between 2005 and 2014. Normal and probable AD participants with a history of TBI were matched to an equal number of demographically and clinically similar participants without a TBI history. In this dataset, TBI with LOC was defined as brain trauma with brief or extended unconsciousness. For the normal and probable AD cohorts, there was an average of 3.2±1.9 and 1.8±1.1 years of follow-up, respectively. 30.8% of the normal cohort were APOEɛ4 carriers, whereas 70.8% of probable AD participants were carriers. Mixed effects regressions showed TBI with LOC history did not affect rates of cognitive change in APOEɛ4 carriers and non-carriers. Findings from this study suggest that TBI with LOC may not alter the course of cognitive function in older adults with and without probable AD. Future studies that better characterize TBI (e.g., severity, number of TBIs, history of subconconcussive exposure) are needed to clarify the association between TBI and long-term neurocognitive outcomes.

Early Functional Limitations in Cognitively Normal Older Adults Predict Diagnostic Conversion to Mild Cognitive Impairment

OBJECTIVES

To examine whether specific types of early functional limitations in cognitively normal older adults are associated with subsequent development of mild cognitive impairment (MCI), as well as the relative predictive value of self versus informant report in predicting diagnostic conversion to MCI.

DESIGN

As a part of a longitudinal study design, participants underwent baseline and annual multidisciplinary clinical evaluations, including a physical and neurological examination, imaging, laboratory work, and neuropsychological testing.

SETTING

Data used in this study were collected as part of longitudinal research at the University of California, Davis Alzheimer's Disease Center.

PARTICIPANTS

Individuals diagnosed as having normal cognition at study baseline who had an informant who could complete informant-based ratings and at least one follow-up visit (N = 324).

MEASUREMENTS

Participants and informants each completed the Everyday Cognition Scale (ECog), an instrument designed to measure everyday function in six cognitively relevant domains.

RESULTS

Self- and informant-reported functional limitations on the ECog were associated with significantly greater risk of diagnostic conversion to MCI (informant: hazard ratio (HR) = 2.0, 95% confidence interval (CI) = 1.3-3.2, P = .002), with self-report having a slightly higher hazard (HR = 2.3, 95% CI = 1.4-3.6, P < .001). When controlling for baseline cognitive abilities, the effect remained significant for self- and informant-reported functional limitations.

CONCLUSION

Deficits in everyday memory and executive function domains were the strongest predictors of diagnostic conversion to MCI. Detection of early functional limitations may be clinically useful in assessing the future risk of developing cognitive impairment in cognitively normal older adults.

Plasma Tau Levels in Cognitively Normal Middle-Aged and Older Adults

Using an ultra-sensitive technique, an immunomagnetic reduction assay, the plasma tau level can be measured to a limit of quantification of pg/ml. In total 126 cognitively normal middle-aged and older adults (45–95 years old) were recruited. The plasma tau levels were significantly higher in the older group (aged 65–95 years) 18.14 ± 7.33 pg/ml than those in the middle-aged group (aged 45–64 years) 14.35 ± 6.49 pg/ml when controlled gender and ApoEε4 carrier status (F = 3.102, P = 0.029). The ApoEε4 carriers had higher plasma tau levels than the non-carriers when controlled age and gender (F = 6.149, P = 0.001). Men had higher plasma tau levels than their women counterparts when controlled ApoEε4 carrier status and gender (F = 6.149, P = 0.001). The plasma tau levels were found to be positively associated with their ages (r = 0.359, P < 0.001). Regression analysis showed that age explained approximately 13% of the variance in the plasma tau levels, and explained more than 10% of the variance in the volumes of the hippocampus and white matter hypodensity (R² change 0.123~0.167, all P < 0.001), and explained less than 10% of the variance in the volume of the amygdala, and central part of the corpus callosum (R² change 0.085~0.097, all P = 0.001). However, the plasma tau levels do not further explain any residual variance in the volume of brain structures. In conclusion, the effect of age on the plasma tau levels should always be considered in clinical applications of this surrogate biomarker to middle-aged and elderly subjects.

Depressive Symptoms and Biomarkers of Alzheimer's Disease in Cognitively Normal Older Adults

Even low levels of depressive symptoms are associated with an increased risk of cognitive decline in older adults without overt cognitive impairment (CN). Our objective was to examine whether very low, "subthreshold symptoms of depression" are associated with Alzheimer's disease (AD) biomarkers of neurodegeneration in CN adults and whether these associations are specific to particular depressive symptoms. We analyzed data from 248 community-dwelling CN older adults, including measurements of cortical amyloid burden, neurodegeneration markers of hippocampal volume (HV) and cerebral 18F-fluorodeoxyglucose (FDG) metabolism in a composite of AD-related regions and the 30-item Geriatric Depression Scale (GDS). Participants with GDS >10 were excluded. General linear regression models evaluated the cross-sectional relations of GDS to HV or FDG in separate backward elimination models. Predictors included GDS total score, age, gender, premorbid intelligence, a binary amyloid variable and its interaction with GDS. Principal component analyses of GDS item scores revealed three factors (the Dysphoria, Apathy-Anhedonia, and Anxiety-Concentration Factors). In secondary analyses, GDS total score was replaced with the three factor scores in repeated models. Higher GDS score (p = 0.03) was significantly associated with lower HV and was marginally related (p = 0.06) to FDG hypometabolism. In secondary models, higher Dysphoria (p = 0.02) and Apathy-Anhedonia (p = 0.05) were related to lower HV while higher Apathy-Anhedonia (p = 0.003) was the sole factor related to FDG hypometabolism. Amyloid was not a significant predictor in any model. In conclusion, very low-level dysphoria, apathy and anhedonia may point to neurodegeneration in AD-related regions but this association appears to be independent of amyloid burden.

Early Brain Loss in Circuits Affected by Alzheimer's Disease is Predicted by Fornix Microstructure but may be Independent of Gray Matter

In a cohort of community-recruited elderly subjects with normal cognition at initial evaluation, we found that baseline fornix white matter (WM) microstructure was significantly correlated with early volumetric longitudinal tissue change across a region of interest (called fornix significant ROI, fSROI), which overlaps circuits known to be selectively vulnerable to Alzheimer’s dementia pathology. Other WM and gray matter regions had much weaker or non-existent associations with longitudinal tissue change. Tissue loss in fSROI was in turn a significant factor in a survival model of cognitive decline, as was baseline fornix microstructure. These findings suggest that WM deterioration in the fornix and tissue loss in fSROI may be the early beginnings of posterior limbic circuit and default mode network degeneration. We also found that gray matter baseline volumes in the entorhinal cortex and hippocampus predicted cognitive decline in survival models. But since GM regions did not also significantly predict brain-tissue loss, our results may imply a view in which early, prodromal deterioration appears as two quasi independent processes in white and gray matter regions of the limbic circuit crucial to memory.

Weight loss and incident dementia in elderly Yoruba Nigerians: a 10-year follow-up study

BACKGROUND

The relationship between weight and dementia risk has not been investigated in populations with relatively low body mass index (BMI) such as the Yoruba. This study set out to achieve this objective using a prospective observational design.

METHODS

The setting was Idikan Ward in Ibadan City, Nigeria. The participants were all aged 65 years or older and were enrolled in the Indianapolis-Ibadan Dementia Project. Repeated cognitive assessments and clinical evaluations were conducted to identify participants with dementia or MCI during 10 years of follow-up (mean duration: 5.97 years). BMI measures, information on alcohol, smoking history, cancer, hypertension, diabetes, heart attack, stroke and depression were collected at each follow-up evaluation. Mixed effect models adjusted for covariates were used to examine the differences in BMI among participants who developed dementia or MCI and those who remained cognitively normal during the follow-up.

RESULTS

This analysis included 1559 participants who had no dementia at their first BMI measurements. There were 136 subjects with incident dementia, 255 with MCI and 1168 with normal cognition by the end of the study. The mean BMI at baseline was higher for female participants (22.31; SD = 4.39) than for male (21.09; SD = 3.61, p < 0.001). A significantly greater decline in BMI was found in those with either incident dementia (p < 0.001) or incident MCI (p < 0.001) compared to normal subjects.

CONCLUSION

Decline in BMI is associated with incident MCI and dementia in elderly Yoruba. This observation calls for close monitoring of weight loss in elderly individuals which may indicate future cognitive impairment for timely detection and tailored interventions.