True, but to a degree. When you click on the link to the study that was provided in the People article “As Little as 8 Alcoholic Drinks a Week Can Contribute to Dementia, Research Says”, it takes you to a press release from the association responsible for the study. The study was done by the American Academy of Neurology (whose goal is to advance neurology learning and to encourage care for brain health), who claim that heavy drinkers that have eight or more drinks every week have an increased risk of having hyaline arteriosclerosis. “Hyaline arteriolosclerosis is a condition that causes the small blood vessels to narrow, becoming thick and stiff. This makes it harder for blood to flow, which can damage the brain over time. It appears as lesions, areas of damaged tissue in the brain” the release says. However, an important detail left out of the People article is that there results couldn’t be completely confirmed, with the press release saying in its first paragraph that “The study does not prove that heavy drinking causes brain injury; it only shows an association”, and it saying at the end of the release that “A limitation of the study was that it did not look at participants before death and did not have information on the duration of alcohol consumption and cognitive abilities.” Also, while the press release does claim that excessive alcohol consumption can increase the chances of facing thinking and memory issues, it never mentions the possible of developing dementia, although it does claim it can increase the risk of developing Alzheimer’s disease, saying “Researchers also found heavy and former heavy drinkers had higher odds of developing tau tangles, a biomarker associated with Alzheimer’s disease, with 41% and 31% higher odds, respectively.” However, there was a separate study done by BMC Public Health titled “Alcohol use disorders and associated chronic disease – a national retrospective cohort study from France” that claimed it it’s results that people with alcohol use disorders had a higher risk of developing dementia, saying that “AUDs were associated with significantly higher risks of hospital admission for all alcohol-attributable disease categories: digestive diseases, cancers (exception: breast cancer), cardiovascular diseases, dementia, infectious diseases, and injuries” (Baillot, Mallet, Rehm, Schwarzinger & Thiebaut). Overall, I would still put this claim as true, but know that the “can” is doing a bit of heavy lifting.
https://www.aan.com/PressRoom/Home/PressRelease/5251
https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-017-4587-y