Study shows increased alcohol consumption directly raises dementia risk

Study: Association between alcohol consumption and the incidence of dementia in current drinkers: linear and nonlinear mendelian randomization analysis. Image credits: jiris / Shutterstock

This is evident from a recent study published in the journal eClinical MedicineResearchers investigated whether increasing alcohol consumption increases the risk of developing dementia among people who currently drink.

Their findings indicate that predicted alcohol consumption based on genetic factors increases, as does the risk of dementia. This challenges previous knowledge and suggests that no amount of alcohol is safe when it comes to dementia prevention.

Background

By 2050, the global number of people living with dementia is expected to rise from over 57 million in 2019 to almost 153 million, underscoring the urgent need for prevention strategies.

Although heavy drinking is a known risk factor for dementia, the effects of consuming light to moderate alcohol are still debated. Previous studies have often been skewed by factors such as ‘non-drinkers’, which occur when people who stop drinking or choose not to drink due to poor health are compared with drinkers, potentially skewing the results.

These studies may also not take into account cognitive decline that occurs earlier in life or interactions with other health problems, leading to mixed evidence on whether light to moderate alcohol consumption reduces the risk of dementia.

Previous studies have used genetic data to mimic a randomized trial and reduce bias, but these studies assumed a linear relationship. It remains unclear whether light to moderate alcohol consumption has a causal effect on the risk of dementia.

About the study

This study used data from the UK Biobank to find out whether drinking light to moderate amounts of alcohol causes a higher risk of dementia in people who currently drink alcohol.

First, researchers looked at the relationship between alcohol and dementia using a common statistical method, which allowed them to see whether the risk changed at different drinking levels.

They then used a genetic approach called Mendelian Randomization (MR) to see if genes linked to alcohol consumption could help determine whether alcohol is directly linked to dementia risk.

The study involved more than 300,000 white British adults who currently drink alcohol. These participants answered questions about their alcohol habits and provided genetic information. People who did not drink or had dementia at the start of the study were excluded.

Alcohol intake was calculated based on how much people said they drank each week, according to UK health guidelines. Dementia cases were tracked via hospital and death records.

The genetic part of the study used information from 95 genes linked to alcohol consumption to find out whether drinking alcohol directly affects the risk of dementia, while adjusting for other factors such as age, gender and lifestyle habits.

Findings

In this study, researchers followed 313,958 current alcohol drinkers for about 13 years to see if their drinking habits were linked to dementia risk. During this time, 1.7% of participants (5,394 people) were diagnosed with dementia.

The average amount of alcohol consumed each week was 13.6 units, with almost half (48.6%) drinking more than the UK recommended 14 units per week.

Men generally drank more than women, with men drinking around 20.2 units per week, compared to 9.5 units for women. Interestingly, more women (68.6%) stayed within safe drinking limits compared to men (34.2%).

When analyzing the relationship between alcohol consumption and dementia, a ‘J-shaped’ pattern was found.

This means that light to moderate drinking (about 11.9 units per week) was associated with the lowest risk of dementia, while higher levels of drinking increased the risk. For men, the lowest risk of dementia was 16.8 units per week, but no clear pattern was found for women.

Genetic analysis showed that people with genes linked to higher alcohol consumption were more likely to develop dementia, especially women. This suggests that alcohol may play a direct role in increasing the risk of dementia, especially with heavier drinking.

Conclusions

The study found a linear relationship between alcohol consumption and the likelihood of developing dementia, with current drinkers at greater risk of dementia as alcohol intake increases.

This contrasts with conventional epidemiology, which often shows a J-shaped relationship, suggesting that moderate drinking could have protective effects.

However, the MR analysis of this study suggests that these protective effects may be due to biases in traditional studies, such as ‘abstainer bias’ or confounding factors such as socio-economic status.

Strengths include the use of MR to minimize confounding and reverse causality, and both linear and non-linear MR analyzes to assess the impact of alcohol on dementia. The study’s limitations include its reliance on self-reported alcohol data, possible biases from selective UK Biobank participants, and its focus on current drinkers, limiting the applicability of the results to other groups.

Future research should include diverse populations to better understand the impact of alcohol on dementia risk among racial and ethnic groups.