Those who didn't drink in middle age were found to have a 45% higher risk of dementia.
A total of almost 400 dementia cases - with onset occurring, on average, at age 76 - were reported. Researchers traced participants' health records for dementia using the databases of the national hospital episode statistics, the Mental Health Services Data Set, and the mortality register.
Scientists at the Universite Paris-Saclay in France found those who did not drink in middle age had a 47 per cent higher risk of dementia compared with those who consumed between one unit and the recommended limit of 14 units of alcohol per week.
In an accompanying BMJ editorial commentary Sevil Yasar, an associate professor at Johns Hopkins University School of Medicine in the United States, said the study contained a number of significant findings.
Above this, though, researchers noted that those that drink heavily risked a 17% rise in risk of developing dementia for every additional 7 units consumed.
"These results suggest that abstention and excessive alcohol consumption are associated with an increased risk of dementia, although the underlying mechanisms are likely to be different in the two groups", the authors said. "However, adjustment for confounding factors did not alter the findings".More news: Barcelona confirm £27m three-year deal for Arturo Vidal
She added that the next steps for research should be confirmation of the findings in other long-term studies, which would need to be "funded exclusively" by government agencies to avoid bias.
"People who completely abstain from alcohol may have a history of heavy drinking and this can make it hard to interpret the links between drinking and health".
After taking account of sociodemographic, lifestyle, and health related factors that could have affected the results, the researchers found that abstinence in midlife or drinking more than 14 units a week was associated with a higher risk of dementia compared with drinking 1-14 units of alcohol a week.
Guidance from the United Kingdom chief medical officer states that men and women should drink no more than 14 units of alcohol each week - the equivalent of six pints of average strength beer.
The team of French and British researchers suggested part of the excess risk of dementia in abstainers could be due to a greater risk of cardiometabolic disease reported in this group. The present study encourages the use of a lower threshold of alcohol consumption in such guidelines, applicable over the adult life course, in order to promote cognitive health.
People who enjoy a drink but think about giving up when they hit their mid-life crisis should think again. This being said, earlier consumption may contribute to higher dementia risk, as the illness "involves neuropathological changes over many years, perhaps decades".