However, heavy drinking is more robustly linked to an increased risk of dementia. This appears to be for a number of reasons.
Firstly, when alcohol is broken down in the body, it produces acetaldehyde, which is toxic to brain cells. Heavy drinking can also lead to thiamine deficiency and, eventually, Wernicke-Korsakoff syndrome, which negatively impacts brain function.
Alcohol misuse is associated with other factors that can influence brain function, such as epilepsyand head injuries. On top of this, alcohol consumption raises the risk of vascular dementia due to its effect on the vascular system as a whole — for instance, it increases blood pressure.
Although the above factors adequately explain why alcohol abuse and dementia may be linked, the exact size and scale of the issue is not clear.
Across the same time period, there were almost 1 million people diagnosed with alcohol use disorders, most of whom had an alcohol dependency diagnosis, too. According to the study authors, alcohol use disorder was "defined by the chronic harmful use of alcohol or alcohol dependence."
Of the dementia cases, around 3 percent were directly attributed to alcohol. But when the team looked at only the early-onset dementia cases, the percentage was much higher.
Even when looking at all types of dementia, alcohol appeared to play a larger part than previously thought. Overall, alcohol use disorders were associated with a threefold increase in the risk of all types of dementia. And importantly, they were found to be the most significant modifiable risk factor for dementia.
When alcohol-related brain damage was excluded, alcohol use disorders still doubled the risk of vascular and other dementias. Even when adjusting the data for confounding variables, the link remained significant.