A French nationwide study, in which scientists assessed 57,000 cases of dementia over five years, found 39 percent of the cases studied could be attributed to alcohol-related brain damage.
Dementia is usually defined as ‘early onset’ when it affects those younger than 65.
The study, carried out by The Translational Health Economics Network, involved over a million hospital patients discharged with dementia and alcohol-related brain damage between 2008 and 2013.
57,000 of the cases were diagnosed before they were 65.
For those diagnosed at later stage, the risk was lower, with three percent of cases linked to alcohol.
Writing in the Lancet Public Health Journal, the researchers who examined the patients’ medical records found that more than half were either heavy drinkers or had other alcohol problems.
Study author Dr Michael Schwarzinger said: ‘Our findings suggest the burden of dementia attributable to alcohol use disorders is much larger than previously thought, suggesting that heavy drinking should be recognised as a major risk factor for all types of dementia.
‘The link between dementia and alcohol use disorders is likely a result of alcohol leading to permanent structural and functional brain damage.’
He added: ‘A variety of measures are needed, such as reducing availability, increasing taxation, and banning advertising and marketing of alcohol, alongside early detection and treatment of alcohol use disorders.’
For this study, ‘heavy-drinking’ was considered to be more than six units a day for men and four for women.
Therefore, the risk may apply to those who exceed the World Health Organisation limit for chronic consumption. For men, it is 7.5 units a day (about three pints of beer) and for women, it is five units a day (about four small glasses of wine).
The Alzheimer’s Society told the BBC it was well aware of the risks, but its advice remained the same: people should not drink more than 14 units of alcohol per week.