The relationship between midlife and late life alcohol consumption, APOE e4 and the decline in learning and memory among older adults

Alzheimer's Disease Risk Reduction Health Coaching: Comparative Analysis

BACKGROUND AND OBJECTIVES

Recent guidelines point to lifestyle as a tool for decreasing Alzheimer's disease (AD) risk. To address the limited practice and availability of AD risk reduction interventions, this study aimed to explore the feasibility of a community-level lifestyle intervention targeting high-risk groups.

RESEARCH DESIGN AND METHODS

Diverse older adults (60+) living in the Richmond, VA, local area, with the following risk factors, incomes below $12,000/year and managing diabetes or cardiovascular disease, were offered weekly lifestyle telephone health coaching for 12 weeks in 2019-2020 (intervention group). The health coaching sessions provided Alzheimer's disease (AD) lifestyle risk reduction education and goal setting/planning. The intervention sample (n = 40, mean age 68 years (range: 60-76 years), was 90% African American/Black (n = 36) and 45% male (n = 18). Thereafter, in 2021-2022, n = 37 individuals in the same area were recruited as a comparison group and not given health coaching (control group), mean age of 65.5 years (range: 57-83 years), 92% African American/Black (n = 34), and 50% male (n = 18).

RESULTS

Repeated-measures intervention effects were seen for cognitive ability, indicating greater improvement in the intervention group (p < .01). Significant difference scores indicated greater cognitive ability (p < .01) and physical activity (p < .001) gains in the intervention group, with intervention subjects with reported memory problems showed relatively less physical activity gains (p < .05).

DISCUSSION AND IMPLICATIONS

This work creates the impetus for future large-scale AD risk reduction investigations to mitigate and improve modifiable risk among diverse older adults. Our positive trends in AD risk reduction support telephone-based health coaching as a feasible AD risk reduction intervention.

Linking alcohol use to Alzheimer's disease: Interactions with aging and APOE along immune pathways

Although it is known that APOE genotype is the strongest genetic risk factor for late-onset Alzheimer's disease, development is a multifactorial process. Alcohol use is a contributor to the epidemic of Alzheimer's disease and related dementias in the US and globally, yet mechanisms are not fully understood. Carriers of the APOE ε4 allele show elevated risk of dementia in relation to several lifestyle factors, including alcohol use. In this review, we describe how alcohol interacts with APOE genotype and aging with potential implications for Alzheimer's disease promotion. Age-related immune senescence and "inflammaging" (i.e., low-grade inflammation associated with aging) are increasingly recognized as contributors to age-related disease. We focus on three immune pathways that are likely contributors to Alzheimer's disease development, centering on alcohol and APOE genotype interactions, specifically: 1) microbial translocation and immune activation, 2) the senescence associated secretory phenotype, and 3) neuroinflammation. First, microbial translocation, the unphysiological movement of gut products into systemic circulation, elicits a proinflammatory response and increases with aging, with proposed links to Alzheimer's disease. Second, the senescence associated secretory phenotype is a set of intercellular signaling factors, e.g., proinflammatory cytokines and chemokines, growth regulators, and proteases, that drives cellular aging when senescent cells remain metabolically active. The senescence associated secretory phenotype can drive development of aging-diseases such as Alzheimer's disease. Third, neuroinflammation occurs via numerous mechanisms such as microglial activation and is gaining recognition as an etiological factor in the development of Alzheimer's disease. This review focuses on interactions of alcohol with APOE genotype and aging along these three pathways that may promote Alzheimer's disease. Further research on these processes may inform development of strategies to prevent onset and progression of Alzheimer's disease and to delay associated cognitive decline.

Divergent Roles of APOAI and APOM in the Identification of Alcohol Use Disorder and Their Association With Inflammation and Cognitive Decline: A Pilot Study

BACKGROUND

Alcohol use disorder (AUD) courses with inflammation and cognitive decline. Apolipoproteins have emerged as novel target compounds related to inflammatory processes and cognition.

METHODS

A cross-sectional study was performed on abstinent AUD patients with at least 1 month of abstinence (n  = 33; 72.7% men) and healthy controls (n  = 34; 47.1% men). A battery of plasma apolipoproteins (APOAI, APOAII, APOB, APOCII, APOE, APOJ, and APOM), plasma inflammatory markers (LPS, LBP), and their influence on cognition and presence of the disorder were investigated.

RESULTS

Higher levels of plasma APOAI, APOB, APOE, and APOJ, as well as the proinflammatory LPS, were observed in the AUD group, irrespective of sex, whereas APOM levels were lower vs controls. Hierarchical logistic regression analyses, adjusting for covariates (age, sex, education), associated APOM with the absence of cognitive impairment in AUD and identified APOAI and APOM as strong predictors of the presence or absence of the disorder, respectively. APOAI and APOM did not correlate with alcohol abuse variables or liver status markers, but they showed an opposite profile in their associations with LPS (positive for APOAI; negative for APOM) and cognition (negative for APOAI; positive for APOM) in the entire sample.

CONCLUSIONS

The HDL constituents APOAI and APOM were differentially regulated in the plasma of AUD patients compared with controls, playing divergent roles in the disorder identification and associations with inflammation and cognitive decline.

Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges

Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.

The interaction effects of age, APOE and common environmental risk factors on human brain structure

Mounting evidence suggests considerable diversity in brain aging trajectories, primarily arising from the complex interplay between age, genetic, and environmental risk factors, leading to distinct patterns of micro- and macro-cerebral aging. The underlying mechanisms of such effects still remain unclear. We conducted a comprehensive association analysis between cerebral structural measures and prevalent risk factors, using data from 36,969 UK Biobank subjects aged 44-81. Participants were assessed for brain volume, white matter diffusivity, Apolipoprotein E (APOE) genotypes, polygenic risk scores, lifestyles, and socioeconomic status. We examined genetic and environmental effects and their interactions with age and sex, and identified 726 signals, with education, alcohol, and smoking affecting most brain regions. Our analysis revealed negative age-APOE-ε4 and positive age-APOE-ε2 interaction effects, respectively, especially in females on the volume of amygdala, positive age-sex-APOE-ε4 interaction on the cerebellar volume, positive age-excessive-alcohol interaction effect on the mean diffusivity of the splenium of the corpus callosum, positive age-healthy-diet interaction effect on the paracentral volume, and negative APOE-ε4-moderate-alcohol interaction effects on the axial diffusivity of the superior fronto-occipital fasciculus. These findings highlight the need of considering age, sex, genetic, and environmental joint effects in elucidating normal or abnormal brain aging.

Within-person associations between alcohol use and memory lapses among middle-aged and older adults

INTRODUCTION

Alcohol use has been linked to impairment in both short- and long-term measures of objective memory. However, limited research has investigated the association between alcohol use and subjective memory in everyday life. The study purpose was to investigate within- and between-person associations between daily alcohol use and prospective (i.e., forgetting an intended task) and retrospective (i.e., forgetting something learned in the past) memory lapses among middle-aged and older adults.

METHODS

Participants (n = 925; Mage  = 55.2) were non-abstaining adults from the Midlife in the United States (MIDUS) study or the MIDUS Refresher who participated in an 8-day telephone diary asking about their daily experiences.

RESULTS

Multilevel models revealed that within-individuals, heavier-than-usual alcohol use (i.e., having more drinks than one's daily average number of drinks) was associated with greater odds of reporting any memory lapses (odds ratio [OR] 1.06; 95% confidence interval [CI] 1.01, 1.12), while associations at the between-person level were nonsignificant (OR 1.07; 95% CI 0.99, 1.16). When assessing retrospective and prospective lapses separately, alcohol use was only associated with prospective lapses and only at the between-person level (OR 1.10; 95% CI 1.01, 1.19). Finally, alcohol use was unassociated with reported irritation or interference from memory lapses (p > 0.05).

DISCUSSION AND CONCLUSIONS

Heavier-than-usual alcohol use may have acute effects on daily memory functioning. Future studies should assess how alcohol use relates to an individual's ability to meet daily cognitive demands, as these findings may have critical implications for harm reduction efforts targeting daily functioning among older adults.

Reelin Plasma Levels Identify Cognitive Decline in Alcohol Use Disorder Patients During Early Abstinence: The Influence of APOE4 Expression

BACKGROUND

Apolipoprotein E (APOE)-4 isoform, reelin, and clusterin share very-low-density liporeceptor and apolipoprotein E receptor 2 receptors and are related to cognition in neuropsychiatric disorders. These proteins are expressed in plasma and brain, but studies involving plasma expression and cognition are scarce.

METHODS

We studied the peripheral expression (plasma and peripheral blood mononuclear cells) of these proteins in 24 middle-aged patients with alcohol use disorder (AUD) diagnosed at 4 to 12 weeks of abstinence (t = 0) and 34 controls. Cognition was assessed using the Test of Detection of Cognitive Impairment in Alcoholism. In a follow-up study (t = 1), we measured reelin levels and evaluated cognitive improvement at 6 months of abstinence.

RESULTS

APOE4 isoform was present in 37.5% and 58.8% of patients and controls, respectively, reaching similar plasma levels in ε4 carriers regardless of whether they were patients with AUD or controls. Plasma reelin and clusterin were higher in the AUD group, and reelin levels peaked in patients expressing APOE4 (P < .05, η2 = 0.09), who showed reduced very-low-density liporeceptor and apolipoprotein E receptor 2 expression in peripheral blood mononuclear cells. APOE4 had a negative effect on memory/learning mainly in the AUD group (P < .01, η2 = 0.15). Multivariate logistic regression analyses identified plasma reelin as a good indicator of AUD cognitive impairment at t = 0. At t = 1, patients with AUD showed lower reelin levels vs controls along with some cognitive improvement.

CONCLUSIONS

Reelin plasma levels are elevated during early abstinence in patients with AUD who express the APOE4 isoform, identifying cognitive deterioration to a great extent, and it may participate as a homeostatic signal for cognitive recovery in the long term.

Prenatal alcohol exposure causes persistent microglial activation and age- and sex- specific effects on cognition and metabolic outcomes in an Alzheimer's Disease mouse model

Background: Prenatal alcohol exposure (PAE) causes behavioral deficits and increases risk of metabolic diseases. Alzheimer's Disease (AD) is a neurodegenerative disease that has a higher risk in adults with metabolic diseases. Both present with persistent neuroinflammation.Objectives: We tested whether PAE exacerbates AD-related cognitive decline in a mouse model (3xTg-AD; presenilin/amyloid precursor protein/tau), and assessed associations among cognition, metabolic impairment, and microglial reactivity.Methods: Alcohol-exposed (ALC) pregnant 3xTg-AD mice received 3 g/kg alcohol from embryonic day 8.5-17.5. We evaluated recognition memory and associative memory (fear conditioning) in 8-10 males and females per group at 3 months of age (3mo), 7mo, and 11mo, then assessed glucose tolerance, body composition, and hippocampal microglial activation at 12mo.Results: ALC females had higher body weights than controls from 5mo (p < .0001). Controls showed improved recognition memory at 11mo compared with 3mo (p = .007); this was not seen in ALC mice. Older animals froze more during fear conditioning than younger, and ALC mice were hyper-responsive to the fear-related cue (p = .017). Fasting blood glucose was lower in ALC males and higher in ALC females than controls. Positive associations occurred between glucose and fear-related context (p = .04) and adiposity and fear-related cue (p = .0002) in ALC animals. Hippocampal microglial activation was higher in ALC than controls (p < .0001); this trended to correlate with recognition memory.Conclusions: ALC animals showed age-related cognitive impairments that did not interact with AD risk but did correlate with metabolic dysfunction and somewhat with microglial activation. Thus, metabolic disorders may be a therapeutic target for people with FASDs.

Midlife alcohol consumption and later life cognitive impairment: Light drinking is not protective and APOE genotype does not change this relationship

INTRODUCTION

Much debate exists about the role of light to moderate alcohol intake and subsequent cognitive function. The apolipoprotein E genotype may modify the relationship.

METHODS

Using data from the Honolulu-Asia Aging Study, a longitudinal population-based cohort (n = 2,416), Cox proportional hazards regression analyses were performed to measure midlife alcohol intake (average age = 52 years) and later life cognitive function (average age = 87 years) and to explore the role of apolipoprotein E genotype.

RESULTS

No protective effect of light drinking (>1 drink/month- 1 drink/day) or moderate drinking (>1-2 drinks/day) was observed in the cohort in adjusted models (HR = 1.013, CI:0.88-1.16; HR = 1.104, CI:0.91-1.34, respectively). Heavy drinking (>2-4 drinks/day) and very heavy drinking (>4 drinks/day) increased the risk for incident moderate cognitive impairment (HR = 1.355, CI:1.09-1.68; HR = 1.462, CI:1.04-2.05, respectively). When examining the relationship by apolipoprotein E ε4 carrier status, a similar dose-response pattern was observed in both groups with higher hazard ratios for those carrying at least one copy of the apolipoprotein E ℇ4 allele. As alcohol level increased, the age at incident moderate cognitive impairment decreased, especially among those with at least one apolipoprotein E ℇ4 allele.

DISCUSSION

We did not observe a significant protective effect for light to moderate drinking in midlife and subsequent cognitive impairment in this cohort. Heavy drinking increased the risk for moderate cognitive impairment and decreased the age at incidence, as did carrying at least one allele of the apolipoprotein E ℇ4 gene.

Effects of sex and genotype in human APOE-targeted replacement mice on alcohol self-administration measured with the automated IntelliCage system before and after repeated mild traumatic brain injury

BACKGROUND

Few studies have examined the association between APOE genotype and alcohol use. Although some of these studies have reported outcomes associated with a history of drinking, none have examined alcohol-seeking behavior. In addition, no preclinical studies have examined alcohol use as a function of APOE genotype with or without traumatic brain injury.

METHODS

Male and female human APOE3- and APOE4-targeted replacement (TR) mice were used to assess voluntary alcohol seeking longitudinally using a 2-bottle choice paradigm conducted within the automated IntelliCage system prior to and following repeated mild TBI (rmTBI). Following an acquisition phase in which the concentration of ethanol (EtOH) was increased to 12%, a variety of drinking paradigms that included extended alcohol access (EAA1 and EAA2), alcohol deprivation effect (ADE), limited access drinking in the dark (DID), and progressive ratio (PR) were used to assess alcohol-seeking behavior. Additional behavioral tasks were performed to measure cognitive function and anxiety-like behavior.

RESULTS

All groups readily consumed increasing concentrations of EtOH (4-12%) during the acquisition phase. During the EAA1 period (12% EtOH), there was a significant genotype effect in both males and females for EtOH preference. Following a 3-week abstinence period, mice received sham or rmTBI resulting in a genotype- and sex-independent main effect of rmTBI on the recovery of righting reflex and a main effect of rmTBI on spontaneous home-cage activity in females only. Reintroduction of 12% EtOH (EAA2) resulted in a significant effect genotype for alcohol preference in males with APOE4 mice displaying increased preference and motivation for alcohol compared with APOE3 mice independent of TBI while in females, there was a significant genotype × TBI interaction under the ADE and DID paradigms. Finally, there was a main effect of rmTBI on increased risk-seeking behavior in both sexes, but no effect on spatial learning or cognitive flexibility.

CONCLUSION

These results suggest that sex and APOE genotype play a significant role in alcohol consumption and may subsequently influence long-term recovery following traumatic brain insults.

APOE Genotype and Alzheimer's Disease: The Influence of Lifestyle and Environmental Factors

Alzheimer's disease (AD) is the most common neurodegenerative disorder with obscure pathogenesis and no disease-modifying therapy to date. AD is multifactorial disease that develops from the complex interplay of genetic factors and environmental exposures. The E4 allele of the gene encoding apolipoprotein E (APOE) is the most common genetic risk factor for AD, whereas the E2 allele acts in a protective manner. A growing amount of epidemiological evidence suggests that several lifestyle habits and environmental factors may interact with APOE alleles to synergistically affect the risk of AD development. Among them, physical exercise, dietary habits including fat intake and ketogenic diet, higher education, traumatic brain injury, cigarette smoking, coffee consumption, alcohol intake, and exposure to pesticides and sunlight have gained increasing attention. Although the current evidence is inconsistent, it seems that younger APOE4 carriers in preclinical stages may benefit mostly from preventive lifestyle interventions, whereas older APOE4 noncarriers with dementia may show the most pronounced effects. The large discrepancies between the epidemiological studies may be attributed to differences in the sample sizes, the demographic characteristics of the participants, including age and sex, the methodological design, and potential related exposures and comorbidities as possible cofounding factors. In this Review, we aim to discuss available evidence of the prominent APOE genotype-environment interactions in regard to cognitive decline with a focus on AD, providing an overview of the current landscape in this field and suggesting future directions.

Precision Nutrition for Alzheimer's Prevention in ApoE4 Carriers

The ApoE4 allele is the most well-studied genetic risk factor for Alzheimer’s disease, a condition that is increasing in prevalence and remains without a cure. Precision nutrition targeting metabolic pathways altered by ApoE4 provides a tool for the potential prevention of disease. However, no long-term human studies have been conducted to determine effective nutritional protocols for the prevention of Alzheimer’s disease in ApoE4 carriers. This may be because relatively little is yet known about the precise mechanisms by which the genetic variant confers an increased risk of dementia. Fortunately, recent research is beginning to shine a spotlight on these mechanisms. These new data open up the opportunity for speculation as to how carriers might ameliorate risk through lifestyle and nutrition. Herein, we review recent discoveries about how ApoE4 differentially impacts microglia and inflammatory pathways, astrocytes and lipid metabolism, pericytes and blood–brain barrier integrity, and insulin resistance and glucose metabolism. We use these data as a basis to speculate a precision nutrition approach for ApoE4 carriers, including a low-glycemic index diet with a ketogenic option, specific Mediterranean-style food choices, and a panel of seven nutritional supplements. Where possible, we integrate basic scientific mechanisms with human observational studies to create a more complete and convincing rationale for this precision nutrition approach. Until recent research discoveries can be translated into long-term human studies, a mechanism-informed practical clinical approach may be useful for clinicians and patients with ApoE4 to adopt a lifestyle and nutrition plan geared towards Alzheimer’s risk reduction.

Interaction between Alcohol Consumption and Apolipoprotein E (ApoE) Genotype with Cognition in Middle-Aged Men

OBJECTIVE

Heavy alcohol consumption is associated with poorer cognitive function in older adults. Although understudied in middle-aged adults, the relationship between alcohol and cognition may also be influenced by genetics such as the apolipoprotein (ApoE) ε4 allele, a risk factor for Alzheimer's disease. We examined the relationship between alcohol consumption, ApoE genotype, and cognition in middle-aged adults and hypothesized that light and/or moderate drinkers (≤2 drinks per day) would show better cognitive performance than heavy drinkers or non-drinkers. Additionally, we hypothesized that the association between alcohol use and cognitive function would differ by ApoE genotype (ε4+ vs. ε4-).

METHOD

Participants were 1266 men from the Vietnam Era Twin Study of Aging (VETSA; M age = 56; range 51-60) who completed a neuropsychological battery assessing seven cognitive abilities: general cognitive ability (GCA), episodic memory, processing speed, executive function, abstract reasoning, verbal fluency, and visuospatial ability. Alcohol consumption was categorized into five groups: never, former, light, moderate, and heavy.

RESULTS

In fully adjusted models, there was no significant main effect of alcohol consumption on cognitive functions. However, there was a significant interaction between alcohol consumption and ApoE ε4 status for GCA and episodic memory, such that the relationship of alcohol consumption and cognition was stronger in ε4 carriers. The ε4+ heavy drinking subgroup had the poorest GCA and episodic memory.

CONCLUSIONS

Presence of the ε4 allele may increase vulnerability to the deleterious effects of heavy alcohol consumption. Beneficial effects of light or moderate alcohol consumption were not observed.

Longitudinal dimensions of alcohol consumption and dietary intake in the Framingham Heart Study Offspring Cohort (1971-2008)

Existing studies addressing alcohol consumption have not captured the multidimensionality of drinking patterns, including drinking frequency, binge drinking, beverage preference and changes in these measures across the adult life course. We examined longitudinal trends in drinking patterns and their association with diet over four decades in ageing US adults from the Framingham Offspring Study (n 4956; baseline mean age 36·2 years). Alcohol intake (drinks/week, drinking frequency, beverage-specific consumption, drinks/occasion) was assessed quadrennially from examinations 1 to 8. Participants were classified as binge drinkers, moderate drinkers or heavy drinkers (4+ and 5+ drinks/occasion; ≤1 and ≤2 drinks/d and >7 and >14 drinks/week for women and men, respectively). Dietary data were collected by a FFQ from examinations 5 to 8 (1991-2008). We evaluated trends in drinking patterns using linear mixed effect models and compared dietary intake across drinking patterns using heterogeneous variance models. Alcohol consumption decreased from 1971 to 2008 (3·7 v. 2·2 oz/week; P < 0·05). The proportion of moderate (66 v. 59·3 %), heavy (18·4 v. 10·5 %) and binge drinkers (40·0 v. 12·3 %) declined (P < 0·05). While average wine consumption increased (1·4 v. 2·2 drinks/week), beer (3·4 v. 1·5 drinks/week) and cocktail intake (2·8 v. 1·2 drinks/week) decreased. Non-binge drinkers consumed less sugary drinks and more whole grains than binge drinkers, and the latter consumed more total fat across all examinations (P < 0·05). There was a significant difference in consumption trends of total grains by drinking level (P < 0·05). In conclusion, alcohol drinking patterns are unstable throughout adulthood. Higher intakes were generally associated with poorer diets. These analyses support the nuanced characterisation of alcohol consumption in epidemiological studies.

Clinical Application of APOE in Alzheimer's Prevention: A Precision Medicine Approach

Population-attributable risk models estimate that up to one-third of Alzheimer's disease (AD) cases may be preventable through risk factor modification. The field of AD prevention has largely focused on addressing these factors through universal risk reduction strategies for the general population. However, targeting these strategies in a clinical precision medicine fashion, including the use of genetic risk factors, allows for potentially greater impact on AD risk reduction. Apolipoprotein E (APOE), and specifically the APOE ε4 variant, is one of the most well-established genetic influencers on late-onset AD risk. In this review, we evaluate the impact of APOE ε4 carrier status on AD prevention interventions, including lifestyle, nutrigenomic, pharmacogenomic, AD comorbidities, and other biological and behavioral considerations. Using a clinical precision medicine strategy that incorporates APOE ε4 carrier status may provide a highly targeted and distinct approach to AD prevention with greater potential for success.

Gene-environment interactions in Alzheimer's disease: A potential path to precision medicine

Alzheimer's disease (AD) is the leading cause of dementia in the United States and afflicts >5.7 million Americans in 2018. Therapeutic options remain extremely limited to those that are symptom targeting, while no drugs have been approved for the modification or reversal of the disease itself. Risk factors for AD including aging, the female sex, as well as carrying an APOE4 genotype. These risk factors have been extensively examined in the literature, while less attention has been paid to modifiable risk factors, including lifestyle, and environmental risk factors such as exposures to air pollution and pesticides. This review highlights the most recent data on risk factors in AD and identifies gene by environment interactions that have been investigated. It also provides a suggested framework for a personalized therapeutic approach to AD, by combining genetic, environmental and lifestyle risk factors. Understanding modifiable risk factors and their interaction with non-modifiable factors (age, susceptibility alleles, and sex) is paramount for designing personalized therapeutic interventions.

Effects of APOE on cognitive aging in community-dwelling older adults

OBJECTIVE

The apolipoprotein E (APOE) gene is an established risk factor for sporadic Alzheimer's disease, with elevated risk for ε4-carriers and reduced risk for ε2-carriers. However, it is unclear whether APOE modifies risk for cognitive decline in normal aging. The objective of this study was to determine whether ε2 and ε4 are associated with rates of normal cognitive aging, and whether associations of ε4 with cognitive decline are modified by sex, education or health behaviors (exercise, alcohol consumption, smoking).

METHOD

A community-based sample of 1,393 older adults were genotyped for APOE and underwent cognitive assessment up to seven times over a maximum of period of 27 years.

RESULTS

ε2-carriers showed slower executive function decline with age relative to ε3 homozygotes or ε4-carriers, whereas ε4-carriers demonstrated more rapid executive function and verbal fluency decline. Accelerated executive function decline was particularly pronounced in ε4-carriers with lower education. After excluding individuals with cognitive impairment, faster executive function decline was still apparent in ε4-carriers, and the effect of ε4 on episodic memory interacted with alcohol consumption, such that only ε4-carriers who did not drink showed more rapid memory decline than ε4 noncarriers. The influence of ε4 on cognitive aging did not differ by sex, nor was it modified by smoking or exercise.

CONCLUSIONS

These findings indicate that the ε2 and ε4 alleles have differential effects on cognitive aging, and that negative effects of ε4 may be partly mitigated by behavioral choices. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Mechanisms of cortisol - Substance use development associations: Hypothesis generation through gene enrichment analysis

There are many theories about the mechanisms of associations between hypothalamic-pituitary-adrenal (HPA) function (indexed by cortisol) and substance use. However, the potential for genes that contribute to both HPA function and substance use to confound the association (e.g., genetic confounding) has largely been ignored. We explore the potential role of genetics in cortisol-substance use associations, build a conceptual framework placing theories and mechanisms for how cortisol and substance use are related into a developmental progression, and develop new hypotheses based on our findings. We conclude that the relationship between cortisol function and substance use is complex, occurs at multiple levels of analysis, and is bidirectional at multiple phases of the substance use progression. Additionally, there is potential for genetic confounding in cortisol-substance use associations, and thus a need for genetically informed designs to investigate how and why cortisol function is associated with substance use phenotypes from initiation through disorder. Gene-environment interplay and developmental context are likely to impact the effectiveness of prevention and intervention efforts to reduce substance use problems.

Moderate alcohol use and apolipoprotein E-4 (ApoE-4): Independent effects on cognitive outcomes in later life

OBJECTIVES

Substantive past research suggests that moderate alcohol use confers beneficial health outcomes. The study of moderate alcohol use and cognition has produced variable findings. The primary goal was to examine the relationship between alcohol use and cognitive aging over time (Experiment 1), in a demographically representative, longitudinal survey of older adults. Experiment 2 examined the hypothesis that apolipoprotein E-4 (ApoE-4) would moderate the relationship between moderate drinking and performance on cognitive domains.

METHOD

The sample was drawn from the Aging, Demographics, and Memory Study (ADAMS) supplement of the Health and Retirement Study (HRS) and included 856 participants over age 65 in 2001. Follow-up data were from 2002, 2006, and 2008. Alcohol use was measured via self-report. Control variables included gender, age, race, number of years of education, medical burden (total number of medical diseases), and marital status.

RESULTS

Results of Experiment 1 indicated that moderate alcohol use was significantly associated with better baseline functioning across cognitive measures (p ≤ .05), but had no significant effect on rate of change over time across cognitive domains. Results of Experiment 2 indicated that while ApoE-4 carriage did not moderate the relationship between alcohol use and cognitive performance, generally, both ApoE-4 and moderate alcohol use were significant predictors of cognitive performance.

CONCLUSIONS

Overall, findings from this study support past findings that moderate alcohol use is associated with better cognitive functioning among community-dwelling older adults, and these relative benefits appear to persist throughout later life. However, the role of individual differences on manifestation of benefit remain very poorly understood. Future research should further examine the respective roles of demographic differences associated with cognitive aging, genetic moderators, and the influence of social interaction.

Alcohol Consumption and Incident Dementia: Evidence from the Sydney Memory and Ageing Study

Alcohol consumption is a potentially modifiable risk factor for dementia, but the literature is not completely consistent. This inconsistency may be partly due to an interaction with the apolipoprotein E (APOE) genotype, an established risk factor for Alzheimer's dementia. The aim of this study was to examine whether alcohol consumption is associated with incident dementia or decline in specific cognitive domains over 4 years, and if this effect is modified by APOEɛ4 status. Non-demented community dwelling older adults (70-90 years) from an ongoing longitudinal study were assessed for cognitive impairment in attention/processing speed, language, executive function, visuospatial ability, and memory. Incident dementia was diagnosed according to DSM-IV criteria. Compared to those who did not drink in the previous 12 months, neither low consumption (HR 0.64 95% CI 0.3-1.4) or risky consumption (HR 0.58 95% CI 0.2-1.5) was associated with incident dementia. Carriers of the APOEɛ4 allele were more likely to develop dementia, but there was no significant interaction with alcohol consumption.