Scientists still do not fully understand what alcohol does to the brain over a lifetime, and they keep probing whether any level of drinking can be called safe. The evidence so far is messy. Some studies have suggested light or moderate drinkers face a lower dementia risk than non-drinkers, but researchers caution that many abstainers in those samples are former heavy drinkers or people already in poor health, which muddies the comparison. Brain imaging work has linked even modest regular drinking to shrinkage in certain regions. Heavy drinking, by contrast, is firmly tied to memory loss and a condition sometimes described as alcohol-related dementia. Researchers also disagree over how much factors such as genetics and drinking habits change the picture. What almost everyone accepts is that binge drinking damages the brain. For now, the honest answer on how much is safe is that nobody can say for certain.