Dr Clive Ballard, University of Exeter Medical School, commented that
"There is a fair amount of evidence that modest alcohol consumption may be protective against dementia, and this study now suggests strongly that heavy drinking is harmful.”
There are of course other factors that might also be contributing to this increased level of risk. People have with high levels of alcohol consumption also tend to have other risk factors for dementia like poor nutrition, and depression.
For reference the World Health Organisation defines chronic heavy drinking as around 6 or more standard drinks on an average day for men, or 4 standard drinks for women.
The researchers analysed 30 Million patient files over a 6 year period. This included “80% of the French population more than 60 years of age” according to the lead author Michaël Schwarzinger, MD, Translational Health Economics Network, Paris.
The researchers found over 1 Million cases of dementia in the patient records the analysed. This was after excluding potential patients who had diseases that could skew the data. The researchers noted that
There was a strong association between a history of alcohol problems and dementia
The association was particularly noticeable in early-onset dementia
57% of people who developed dementia under the age of 65 having a history of “alcohol use disorders” (66% of Men and 37% of Women)
Dr Schwarzinger also noted that although it was unclear how much people in the study were drinking
" … usually anyone with an alcohol use disorder would be drinking more than 5 units of alcohol a day,"
So it appears that alcohol consumption is a strong, but modifiable, risk factor for dementia.