Alcohol consumption and lifetime change in cognitive ability: a gene × environment interaction study

Alcohol consumption's effects on working memory: Examining familial confounding

OBJECTIVE

The purpose of our study was to provide a more rigorous test of the causal hypothesis that chronic alcohol use impairs working memory performance.

METHOD

We measured linear associations between a latent factor representing alcohol consumption and accuracy across four working memory tasks before and after accounting for familial confounding using a cotwin control design. Specifically, this study examined accuracy through a latent working memory score, the National Institutes of Health (NIH) Toolbox List Sorting, NIH Toolbox Picture Sequence, Penn Word Memory, and 2-back tasks. The study included data from 158 dizygotic and 278 monozygotic twins (Mage = 29 ± 3 years).

RESULTS

In our initial sample-wide analysis, we did not detect any statistically significant associations between alcohol use and working memory accuracy. However, our cotwin control analyses showed that twins with greater levels of alcohol use exhibited worse scores on the latent working memory composite measure (B = -.25, CI [-.43, -.08], p < .01), Picture Sequence (B = -.31, CI [-.55, -.08], p < .01), and List Sorting (B = -.28, CI [-.51, -.06 ], p = .01) tasks than did their cotwins.

CONCLUSIONS

These results are consistent with a potentially causal relationship between alcohol use and working memory performance that can be detected only after accounting for confounding familial factors. This highlights the importance of understanding the mechanisms that may underlie negative associations between alcohol use and cognitive performance, as well as the potential factors that influence both alcohol behaviors and cognition. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Methodological approaches, challenges, and opportunities in the application of Mendelian randomisation to lifecourse epidemiology: A systematic literature review

Diseases diagnosed in adulthood may have antecedents throughout (including prenatal) life. Gaining a better understanding of how exposures at different stages in the lifecourse influence health outcomes is key to elucidating the potential benefits of disease prevention strategies. Mendelian randomisation (MR) is increasingly used to estimate causal effects of exposures across the lifecourse on later life outcomes. This systematic literature review explores MR methods used to perform lifecourse investigations and reviews previous work that has utilised MR to elucidate the effects of factors acting at different stages of the lifecourse. We conducted searches in PubMed, Embase, Medline and MedRXiv databases. Thirteen methodological studies were identified. Four studies focused on the impact of time-varying exposures in the interpretation of "standard" MR techniques, five presented methods for repeat measures of the same exposure, and four described methodological approaches to handling multigenerational exposures. A further 127 studies presented the results of an applied research question. Over half of these estimated effects in a single generation and were largely confined to the exploration of questions regarding body composition. The remaining mostly estimated maternal effects. There is a growing body of research focused on the development and application of MR methods to address lifecourse research questions. The underlying assumptions require careful consideration and the interpretation of results rely on select conditions. Whilst we do not advocate for a particular strategy, we encourage practitioners to make informed decisions on how to approach a research question in this field with a solid understanding of the limitations present and how these may be affected by the research question, modelling approach, instrument selection, and data availability.

Using Mendelian randomization analysis to better understand the relationship between mental health and substance use: a systematic review

BACKGROUND

Poor mental health has consistently been associated with substance use (smoking, alcohol drinking, cannabis use, and consumption of caffeinated drinks). To properly inform public health policy it is crucial to understand the mechanisms underlying these associations, and most importantly, whether or not they are causal.

METHODS

In this pre-registered systematic review, we assessed the evidence for causal relationships between mental health and substance use from Mendelian randomization (MR) studies, following PRISMA. We rated the quality of included studies using a scoring system that incorporates important indices of quality, such as the quality of phenotype measurement, instrument strength, and use of sensitivity methods.

RESULTS

Sixty-three studies were included for qualitative synthesis. The final quality rating was '-' for 16 studies, '- +' for 37 studies, and '+'for 10 studies. There was robust evidence that higher educational attainment decreases smoking and that there is a bi-directional, increasing relationship between smoking and (symptoms of) mental disorders. Another robust finding was that higher educational attainment increases alcohol use frequency, but decreases binge-drinking and alcohol use problems, and that mental disorders causally lead to more alcohol drinking without evidence for the reverse.

CONCLUSIONS

The current MR literature increases our understanding of the relationship between mental health and substance use. Bi-directional causal relationships are indicated, especially for smoking, providing further incentive to strengthen public health efforts to decrease substance use. Future MR studies should make use of large(r) samples in combination with detailed phenotypes, a wide range of sensitivity methods, and triangulate with other research methods.

The causal web of foetal alcohol spectrum disorders: a review and causal diagram

Foetal alcohol spectrum disorders (FASDs) are a leading cause of developmental disability. Prenatal alcohol use is the sole necessary cause of FASD, but it is not always sufficient. Multiple factors influence a child's susceptibility to FASD following prenatal alcohol exposure. Much of the FASD risk factor literature has been limited to discussions of association, rather than causation. While knowledge of predictor variables is important for identifying who is most at risk of FASD and for targeting interventions, causal knowledge is important for identifying effective mechanisms for prevention and intervention programmes. We conducted a systematic search and narrative synthesis of the evidence and used this to create a causal diagram (directed acyclic graph; DAG) to describe the causal pathways to FASD. Our results show that the aetiology of FASD is multifaceted and complex. FASD risk is determined by a range of lifestyle, sociodemographic, maternal, social, gestational, and genetic factors. The causal diagram that we present in this review provides a comprehensive summary of causal risk factors for FASD and can be used as a tool to inform data collection and statistical modelling strategies to minimise bias in future studies of FASD.

Lifetime alcohol use and cognitive performance in older adults

Substance use is an important clinical issue in the older adult population. As older adults are susceptible to cognitive disorders, the intersection of the fields of substance use and cognitive neuroscience is an active area of research. Prior studies of alcohol use and cognitive performance are mixed, and inconsistencies may be due to under- or over-adjustment for confounders. This article adds to this literature by conducting a secondary analysis of self-reported lifetime history of alcohol use and cognitive performance in older adults (n = 133). It was hypothesized that current alcohol users would have poorer cognitive performance compared to never/minimal and former alcohol users. Older adult participants were classified into never/minimal alcohol users, former alcohol users, and current alcohol users. A neurocognitive battery included a global cognitive measure and individual measures of attention, memory, fluency, and executive function. A directed acyclic graph-based approach was used to select variables to be included in the multiple linear regression models. Though unadjusted analyses showed some significant associations between alcohol use and cognitive performance, all associations between alcohol use and cognitive performance were eliminated after adjusting for age, education, sex, race, and smoking pack years. Alcohol drink years were not significantly associated with cognitive performance among current and former alcohol users. These results suggest that lifetime alcohol use is not significantly associated with cognitive performance in older adults after adjustment for key confounders. Inconsistencies in prior studies may be due to uncontrolled confounding and/or unnecessary adjustment of mediators and/or colliders.

Variation in an Iron Metabolism Gene Moderates the Association Between Blood Lead Levels and Attention-Deficit/Hyperactivity Disorder in Children

Although attention-deficit/hyperactivity disorder (ADHD) is a heritable neurodevelopmental condition, there is also considerable scientific and public interest in environmental modulators of its etiology. Exposure to neurotoxins is one potential source of perturbation of neural, and hence psychological, development. Exposure to lead in particular has been widely investigated and is correlated with neurodevelopmental outcomes, including ADHD. To investigate whether this effect is likely to be causal, we used a Mendelian randomization design with a functional gene variant. In a case-control study, we examined the association between ADHD symptoms in children and blood lead level as moderated by variants in the hemochromatosis (HFE) gene. The HFE gene regulates iron uptake and secondarily modulates lead metabolism. Statistical moderation was observed: The magnitude of the association of blood lead with symptoms of ADHD was altered by functional HFE genotype, which is consistent with a causal hypothesis.

Alcohol consumption and mortality in patients with mild Alzheimer's disease: a prospective cohort study

OBJECTIVE

To investigate the association between alcohol consumption and mortality in patients recently diagnosed with mild Alzheimer's disease (AD).

DESIGN

A post hoc analysis study based on a clinical trial population.

SETTING

The data reported were collected as part of the Danish Alzheimer's Intervention Study (DAISY), a longitudinal multicentre randomised controlled study on the efficacy of psychosocial intervention in patients with mild AD across five county districts in Denmark.

PARTICIPANTS

321 patients with mild AD (Mini-Mental State Examination ≥ 20) were included. Data regarding current daily alcohol consumption were obtained from the patient's primary caregivers at inclusion.

MAIN OUTCOME

All-cause mortality retrieved from The Danish Civil Registration System over a period of 36 months after baseline.

RESULTS

Information about alcohol consumption was obtained from all 321 study participants: 8% were abstinent, 71% only had alcohol occasionally (1 or <1 unit/day), 17% had 2-3 units/day and 4% had more than 3 units/day. An analysis adjusted for a range of potential confounders demonstrated a reduced mortality for patients with moderate alcohol consumption (2-3 units/day): HR 0.23 (95% CI (0.08 to 0.69)) compared with patients who had 1 or <1 unit/day. Mortality was not significantly different in abstinent patients or in patients with an alcohol consumption of more than 3 units/day, compared with patients drinking 1 or <1 unit/day.

CONCLUSIONS

In this cohort of patients with mild AD, moderate alcohol consumption (2-3 units/day) was associated with a significantly lower mortality over a period of 36 months. Further studies are needed in this area. These may especially focus on the association between alcohol consumption and cognitive decline in patients with AD.

Alcohol consumption, drinking patterns, and cognitive function in older Eastern European adults

Objective:

To investigate associations of frequency, quantity, binge, and problem drinking with cognitive function in older Eastern European adults.

Methods:

The investigation included 14,575 participants, aged 47 to 78 years at cognitive assessment in 2006–2008 from Novosibirsk (Russia), Krakow (Poland), and 6 Czech towns participating in the HAPIEE (Health, Alcohol, and Psychosocial Factors in Eastern Europe) prospective cohort study. Average response rates were 59% at baseline (2002–2005) and 63% in 2006–2008. Alcohol consumption was assessed at baseline and in 2006–2008. Cognitive tests included immediate and delayed word recall, semantic fluency (animal naming), and letter cancellation. Associations between alcohol indices and cognitive scores were analyzed cross-sectionally (all measures from 2006 to 2008) and prospectively (alcohol and covariates from 2002 to 2005 and cognition from 2006 to 2008).

Results:

In cross-sectional analyses, nondrinkers had lower cognitive scores and female moderate drinkers had better cognitive performance than light drinkers. Heavy, binge, and problem drinking were not consistently associated with cognitive function. Few associations were replicated in prospective analyses. Participants who stopped drinking during follow-up had worse cognition than stable drinkers; in men, regression coefficients (95% confidence interval) ranged from −0.26 (−0.36, −0.16) for immediate recall to −0.14 (−0.24, −0.04) for fluency.

Conclusion:

Regular and episodic heavy drinking were not consistently associated with cognitive function. Worse cognition in participants who stopped drinking during follow-up suggests that inclusion of less healthy ex-drinkers may partly explain poorer cognition in nondrinkers.

Association of smoking and alcohol drinking with dementia risk among elderly men in China

BACKGROUND

Previous studies relating smoking and alcohol drinking with the incidence of dementia have been inconsistent.

OBJECTIVES

We assessed whether smoking and alcohol drinking was associated with the risk of dementia, including Alzheimer disease (AD) and vascular dementia (VaD) after seven years of follow-up.

DESIGN

We prospectively analysed the incidence of dementia from 2004 to 2011 among 2959 elderly men, according to their smoking and alcohol drinking status.

SETTING

six neighbourhoods from three districts mentioned in Chongqing city.

PARTICIPANTS

A total of 3170 men were followed up annually for 7 years.

MEASUREMENTS

Cox proportional hazards models were established to evaluate the association between smoking, alcohol drinking and the risk of dementia.

RESULTS

The incidences of AD and VaD were higher respectively in current smoking than never smoking, daily drinking than never drinking over 7 years of follow-up (p<0.01). After adjusting for age and other potential confounders, current smoking was associated with increased risk of AD (HR= 2.14, 95% CI 1.20-4.46) and VaD (HR= 3.28, 95% CI 1.14-4.52), meanwhile, daily drinking was related to increased risk of AD (HR= 2.25, 95% CI 1.43-3.97) and VaD (HR= 3.42, 95% CI 1.18-4.51). In addition, co-smoking and drinking were related to with a significantly higher risk of AD and VaD than non-smoking and drinking (HR= 3.03, 95% CI 1.65-4.19) and VaD (HR= 3.96, 95% CI 1.64-4.71). Moreover, co-smoking and drinking had higher risk of AD and VaD compared with current smoking and daily drinking.

CONCLUSIONS

Current smoking and daily drinking were found to be significantly associated with dementia in elderly men.