Does alcohol cause dementia?

Turns out, alcohol consumption is one of the biggest risk factors for dementia.

According to a new research conducted by the Centre for Addiction and Mental Health, alcohol use disorders are the most important preventable risk factors for the onset of all types of dementia, especially early-onset dementia.

This study, conducted over one million adults diagnosed with dementia in France, looked specifically at the effect of alcohol use disorders and included people who had been diagnosed with mental and behavioural disorders or chronic diseases that were attributable to the chronic harmful use of alcohol.

Of the 57,000 cases of early-onset dementia (before the age of 65), the majority (57 percent) were related to chronic heavy drinking.

The World Health Organization (WHO) defines chronic heavy drinking as consuming more than 60 grams pure alcohol on average per day for men (4-5 Canadian standard drinks) and 40 grams (about 3 standard drinks) per day for women.

As a result of the strong association found in this study, the authors suggested that screening, brief interventions for heavy drinking, and treatment for alcohol use disorders should be implemented to reduce the alcohol-attributable burden of dementia.

"The findings indicate that heavy drinking and alcohol use disorders are the most important risk factors for dementia, and especially important for those types of dementia which start before age 65, and which lead to premature deaths," said study co-author Jürgen Rehm. "Alcohol-induced brain damage and dementia are preventable, and known-effective preventive and policy measures can make a dent in premature dementia deaths."

Rehm pointed out that on average, alcohol use disorders shorten life expectancy by more than 20 years, and dementia is one of the leading causes of death for these people.

For early-onset dementia, there was a significant gender split. While the overall majority of dementia patients were women, almost two-thirds of all early-onset dementia patients (64.9 percent) were men.

Alcohol use disorders were also associated with all other independent risk factors for dementia onset, such as tobacco smoking, high blood pressure, diabetes, lower education, depression, and hearing loss, among modifiable risk factors. It suggested that alcohol use disorders may contribute in many ways to the risk of dementia.

"As a geriatric psychiatrist, I frequently see the effects of alcohol use disorder on dementia, when unfortunately alcohol treatment interventions may be too late to improve cognition," said researcher Bruce Pollock. "Screening for and reduction of problem drinking, and treatment for alcohol use disorders need to start much earlier in primary care."

The authors also noted that only the most severe cases of alcohol use disorder - ones involving hospitalisation - were included in the study. This could mean that, because of ongoing stigma regarding the reporting of alcohol-use disorders, the association between chronic heavy drinking and dementia may be even stronger.

The findings from the study are published in the journal Lancet Public Health.