MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The association of heavy drinking with dementia has been known for decades. For instance, there is about no Wernicke–Korsakoff syndrome without heavy drinking and the syndrome was described in 1890. But this type of dementia is very rare. Also, heavy drinking is knowingly associated with multiple risk factors for dementia onset such as hypertension or diabetes. But heavy drinkers generally refuse to participate to cohort studies and declaration of alcohol use among participants is generally biased downward… So the study rationale is very strong, but supporting empirical evidence is quite scarce.
This nationwide study included all 31+ million adults discharged from hospitals over 6 years, i.e., 50% of the French population before 65 years old and 80% above that age. Of 1.1+ million adults diagnosed with dementia, one in twenty had an early-onset (before 65 years old). Heavy drinking was recorded in most (56%) early-onset dementia cases: two-third in men; one-third in women. In addition, the association of heavy drinking with dementia goes far beyond 65 years old, both directly (>3 times higher risk for dementia onset after controlling for more than 30 known risk factors for dementia) and indirectly as heavy drinking was associated with all other independent risk factors for dementia onset. Accordingly, heavy drinking had the largest effect on dementia risk of all independent modifiable risk factors such as hypertension or diabetes.
The effects were found whatever dementia case definition or population studies.