Does Abstinence and Heavy Drinking Increase Dementia Risk?

Peter Russell

August 02, 2018

People who abstain from alcohol or who drink in excess of the UK recommended guidelines of 14 units a week during middle age may be at increased risk of developing dementia, according to a study.

The research, published in The BMJ, said that the underlying mechanisms were likely to be different in each case.

Previous research has suggested that drinking moderate amounts of alcohol could lower dementia risk, with harmful effects seen in both abstainers and heavy drinkers. However, evidence has been inconsistent and far from robust. For instance, most studies assessed alcohol consumption in later life and the results might not have reflected lifetime drinking levels.

Three Decades of UK Data

To explore the relationship further, researchers from Inserm in France and University College London (UCL) drew on data from 9087 UK civil servants aged 35 to 55 who were recruited to the Whitehall II study examining socioeconomic effects on health.

Alcohol consumption and alcohol dependence were assessed at regular intervals between 1985 and 1993 when the average age of participants was 50. They were categorised as either abstainers, people who drank between 1 and 14 units a week, and those who consumed more than 14 units each week.

Alcohol consumption trajectories between 1985 and 2004 were also used to examine the association of long-term alcohol consumption and risk of dementia from midlife to early old age. 
 
The data was linked to hospital admissions for alcohol related chronic diseases and cases of dementia between 1991 and 2017.

Of the 9087 participants, 397 cases of dementia were recorded over an average follow-up period of 23 years. Average age at dementia diagnosis was 76 years.
 

Drinking Levels and Dementia Risk

Analysis showed that abstinence in midlife was associated with a 47% higher risk of dementia compared with those who drank between 1 and 14 units a week.

Among those who drank more than 14 units a week, the researchers noted a 17% increase in the risk of dementia for every 7 unit increase in alcohol consumption.

Alcohol consumption trajectories from midlife to early old age showed that long term abstinence and a decrease in consumption also appeared to increase dementia risk.

Further analysis suggested that some of the excess risk of dementia in abstainers was explained by greater risk of cardiometabolic disease in this group.

The authors said their findings were limited by the observational nature of their investigation and that alcohol consumption was self-reported. Nevertheless, they said the results "support the recent downward revision of UK guidelines that moved the recommended alcohol consumption limit to 14 units per/week in men compared with 21 units/week before, bringing them in line with women".
 

Reaction to the Findings

Commenting on the findings, Dr Sara Imarisio, head of research at Alzheimer's Research UK, said: "Past studies of alcohol and dementia risk have tended to record how much people drink at a single point in time, but the strength of this study is that the researchers have been able to track changes in people's drinking over a number of years during midlife.

"As this study only looked at people's drinking in midlife, we don't know about their drinking habits earlier in adulthood, and it is possible that this may contribute to their later life dementia risk. People who completely abstain from alcohol may have a history of heavy drinking and this can make it difficult to interpret the links between drinking and health."

Dr Doug Brown, chief policy and research officer at the Alzheimer's Society, said: "By finding evidence that drinking lots of alcohol, and also drinking no alcohol at all both increase dementia risk, this study supports other work that continues to question whether drinking up to the equivalent of 6 glasses of wine per week might have a protective effect against dementia. However, as this is an observational study we need longer trials to explore whether this is actually the case."

Clive Ballard, professor of age-related diseases at the University of Exeter Medical School, said: "The increased risk in people who are abstinent from alcohol intake compared to those with modest intake is very consistent with previous research, but needs to be interpreted with caution as it may be more likely to reflect differences in other health conditions and differences in cultural backgrounds in people who are abstinent from alcohol."

Alcohol consumption and risk of dementia: 23 year follow-up of Whitehall II cohort study, Sabia et al, BMJ 2018;362:k2927 http://dx.doi.org/10.1136/bmj.k2927.

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