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

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.

Alcohol use, dementia risk, and sex: a systematic review and assessment of alcohol-attributable dementia cases in Europe

BACKGROUND

High-risk alcohol use is an established modifiable risk factor for dementia. However, prior reviews have not addressed sex differences in alcohol-related dementia risk. In this systematic review, we take a sex-specific perspective towards the alcohol-dementia link, taking into account the age of dementia onset.

METHODS

We searched electronic databases for original cohort or case-control studies investigating the association between alcohol use and dementia. Two restrictions were considered: First, studies had to report results stratified by sex. Second, given the fact that the age at dementia onset seems to affect the alcohol-dementia link, studies were required to distinguish between early-onset and late-onset dementia (cut-off: 65 years). Additionally, the contribution of alcohol to dementia incidence was quantified for a set of 33 European countries for the year 2019.

RESULTS

We reviewed 3,157 reports, of which 7 publications were finally included and summarised narratively. A lower dementia risk when drinking alcohol infrequent or at moderate levels was found in men (three studies) and women (four studies). High-risk use and alcohol use disorders increased the risk of mild cognitive impairment and dementia, particularly early-onset dementia. Estimating the alcohol-attributable share of incident dementia cases revealed that 3.2% and 7.8% of incident dementia cases were estimated to be attributable to high-risk alcohol use (at least 24 g of pure alcohol per day) in 45-to-64-year-old women and men, respectively.

CONCLUSIONS

Research to date has paid little attention to the sex-specific link of alcohol and dementia. In the absence of sex-specific research, the established recommendations on high-risk alcohol use should be employed to communicate the alcohol-attributable dementia risk.

Alcohol use and cognitive aging in middle-aged men: The Vietnam Era Twin Study of Aging

OBJECTIVE

To determine associations of alcohol use with cognitive aging among middle-aged men.

METHOD

1,608 male twins (mean 57 years at baseline) participated in up to three visits over 12 years, from 2003-2007 to 2016-2019. Participants were classified into six groups based on current and past self-reported alcohol use: lifetime abstainers, former drinkers, very light (1-4 drinks in past 14 days), light (5-14 drinks), moderate (15-28 drinks), and at-risk drinkers (>28 drinks in past 14 days). Linear mixed-effects regressions modeled cognitive trajectories by alcohol group, with time-based models evaluating rate of decline as a function of baseline alcohol use, and age-based models evaluating age-related differences in performance by current alcohol use. Analyses used standardized cognitive domain factor scores and adjusted for sociodemographic and health-related factors.

RESULTS

Performance decreased over time in all domains. Relative to very light drinkers, former drinkers showed worse verbal fluency performance, by -0.21 SD (95% CI -0.35, -0.07), and at-risk drinkers showed faster working memory decline, by 0.14 SD (95% CI 0.02, -0.20) per decade. There was no evidence of protective associations of light/moderate drinking on rate of decline. In age-based models, light drinkers displayed better memory performance at advanced ages than very light drinkers (+0.14 SD; 95% CI 0.02, 0.20 per 10-years older age); likely attributable to residual confounding or reverse association.

CONCLUSIONS

Alcohol consumption showed minimal associations with cognitive aging among middle-aged men. Stronger associations of alcohol with cognitive aging may become apparent at older ages, when cognitive abilities decline more rapidly.

Associations Between Ambient Air Pollution and Cognitive Abilities from Midlife to Early Old Age: Modification by APOE Genotype

BACKGROUND

Fine particulate matter (PM2.5) and nitrogen dioxide (NO2) measures of ambient air pollution are associated with accelerated age-related cognitive impairment, and Alzheimer's disease and related dementias (ADRD).

OBJECTIVE

We examined associations between air pollution, four cognitive factors, and the moderating role of apolipoprotein E (APOE) genotype in the understudied period of midlife.

METHODS

Participants were ∼1,100 men in the Vietnam Era Twin Study of Aging. Baseline cognitive assessments were from 2003 to 2007. Measures included past (1993-1999) and recent (3 years prior to baseline assessment) PM2.5 and NO2 exposure, in-person assessment of episodic memory, executive function, verbal fluency, and processing speed, and APOE genotype. Average baseline age was 56 years with a 12-year follow-up. Analyses adjusted for health and lifestyle covariates.

RESULTS

Performance in all cognitive domains declined from age 56 to 68. Higher PM2.5 exposures were associated with worse general verbal fluency. We found significant exposure-by-APOE genotype interactions for specific cognitive domains: PM2.5 with executive function and NO2 with episodic memory. Higher PM2.5 exposure was related to worse executive function in APOE ɛ4 carriers, but not in non-carriers. There were no associations with processing speed.

CONCLUSION

These results indicate negative effects of ambient air pollution exposure on fluency alongside intriguing differential modifications of cognitive performance by APOE genotype. APOE ɛ4 carriers appeared more sensitive to environmental differences. The process by which air pollution and its interaction with genetic risk for ADRD affects risk for later life cognitive decline or progression to dementia may begin in midlife.

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.

Paradoxical cognitive trajectories in men from earlier to later adulthood

Because longitudinal studies of aging typically lack cognitive data from earlier ages, it is unclear how general cognitive ability (GCA) changes throughout the life course. In 1173 Vietnam Era Twin Study of Aging (VETSA) participants, we assessed young adult GCA at average age 20 and current GCA at 3 VETSA assessments beginning at average age 56. The same GCA index was used throughout. Higher young adult GCA and better GCA maintenance were associated with stronger specific cognitive abilities from age 51 to 73. Given equivalent GCA at age 56, individuals who had higher age 20 GCA outperformed those whose GCA remained stable in terms of memory, executive function, and working memory abilities from age 51 to 73. Thus, paradoxically, despite poorer maintenance of GCA, high young adult GCA still conferred benefits. Advanced predicted brain age and the combination of elevated vascular burden and APOE-ε4 status were associated with poorer maintenance of GCA. These findings highlight the importance of distinguishing between peak and current GCA for greater understanding of cognitive aging.

How Well Does Subjective Cognitive Decline Correspond to Objectively Measured Cognitive Decline? Assessment of 10-12 Year Change

BACKGROUND

Although not strongly correlated with current objective cognitive ability, subjective cognitive decline (SCD) is a risk factor for Alzheimer's disease. Most studies focus on SCD in relation to future decline rather than objective prior decline that it purportedly measures.

OBJECTIVE

We evaluated whether self-report of cognitive decline-as a continuous measure-corresponds to objectively-assessed episodic memory and executive function decline across the same period.

METHODS

1,170 men completed the Everyday Cognition Questionnaire (ECog) at mean age 68 assessing subjective changes in cognitive ability relative to 10 years prior. A subset had mild cognitive impairment (MCI), but MCI was diagnosed without regard to subjective decline. Participants completed up to 3 objective assessments of memory and executive function (M = 56, 62, and 68 years). Informant-reported ECogs were completed for 1,045 individuals. Analyses controlled for depression and anxiety symptoms assessed at mean age 68.

RESULTS

Participant-reported ECog scores were modestly associated with objective decline for memory (β= -0.23, 95%CI [-0.37, -0.10]) and executive function (β= -0.19, 95%CI [-0.33, -0.05]) over the same time period. However, these associations were nonsignificant after excluding MCI cases. Results were similar for informant ratings. Participant-rated ECog scores were more strongly associated with concurrent depression and anxiety symptoms, (β= 0.44, 95%CI [0.36, 0.53]).

CONCLUSION

Continuous SCD scores are correlated with prior objective cognitive changes in non-demented individuals, though this association appears driven by individuals with current MCI. However, participants' current depression and anxiety ratings tend to be strongly associated with their SCD ratings. Thus, what primarily drives SCD ratings remains unclear.