Heavy drinking biggest risk factor for dementia: Lancet

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While some research has linked heavy drinking to dementia other studies found that moderate levels of alcohol may protect against the disease.

The study, published Tuesday in the journal Lancet Public Health, looked at over 1 million adults released from French hospitals between 2008 and 2013 who were diagnosed with dementia, a clinical syndrome characterized by a progressive deterioration in cognitive ability.

Analysis revealed that alcohol use disorders were linked to a threefold increased risk for all types of dementia and "were the strongest modifiable risk factor for dementia onset" (adjusted HR = 3.34 [95% CI, 3.28-3.41] for women; HR = 3.36 [95% CI, 3.31-3.41] for men). "The study just shows that you are more likely to be in hospital with a diagnosis of dementia if you drink more heavily".

But even when the researchers controlled for factors like high blood pressure, obesity and tobacco smoking, heavy alcohol use was still associated with a more than threefold increase in dementia among both sexes.

The bottom line? "Alcohol use disorders were a major risk factor for onset of all types of dementia, and especially early-onset dementia" per the study.

'This study in no way suggests that moderate alcohol intake could cause early-onset dementia. But heavy drinkers generally refuse to participate to cohort studies and declaration of alcohol use among participants is generally biased downward...

"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 Dr. Bruce Pollock, vice president of research at CAMH.

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.

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Those who are at risk of dementia are people consuming more than a couple of alcoholic drinks a day.

"This large study provides further evidence that heavy drinking is associated with a greatly elevated risk of cognitive impairment, and that this can occur at a relatively young age", observed Killian Welch, PhD, of the University of Edinburgh, who was not involved in the study. However, they point out that they only included the most severe cases of alcohol use in their study - those that required hospitalisation. Other alcohol use disorders were recorded in nearly 5% of all dementia cases (52,625/1,109,343 cases).

That equates to around six or more standard drinks for men and four for women.

"Gender differences on dementia onset have been puzzling for decades", Schwarzinger said. Alcohol use disorder was the primary exposure, and dementia was the main outcome.

Though the study had a very large sample size, it looked at individuals in only one country, making it hard to generalize across cultures.

Heavy drinking is defined by the World Health Organization and the European Medicines Agency as drinking at least 60 g of pure alcohol daily for men and at least 40 g for women per day, the authors explained.

"This is a worthwhile study but it does not prove that dementia has been caused by people drinking alcohol or that people who now drink alcohol will develop dementia".