According to a recent study by the journal Neurology, increased alcohol consumption in middle aged men can affect mental ability. The study was published on the 15th of January 2014 by the study author Severine Sabia from the University College London.
The study of about 5,000 British civil servants found that over a ten year period the decline of their metal abilities was equal to two extra years of aging for a combined measure of abilities like reasoning and about 6 extra years aging for memory. The effects were seen to be increased in those who drank heavily and the level of consumption was used as a comparison. The results are based only on men as no effects were found in the female subjects however there were too few women involved too obtain an accurate measurement in comparison to the male participants.
Although we may already know that alcohol abuse can affect our brain activity, studies are usually on the elderly or young people so the findings of this study could be helpful in further understanding the ramifications of alcohol abuse.
s average age was 56 years old. There mental abilities were then tested every five years for a total of ten years and the level (if any) of decline was recorded.  Not surprisingly the highest levels of decline in metal ability were recorded among the heaviest drinkers in the study, which totalled 469 men. There was a wide range the amount of alcohol consumed amongst this group, the minimum was about 30 ounces of beer and the maximum was about three times that.
The results though seem somewhat broad and have been questioned by others such as Sara Jo Nixon, a substance abuse researcher at the University of Florida in Gainsville. She stated that men at the minimum drinking levels are not necessarily at risk because the results relate to the category overall. She also said that the study only shows a link between the drinking and mental ability decline but does not prove that the alcohol intake is entirely responsible. She continued to say that because of the sensitive mental tests used in the study, the extra declines may be too subtle to make a difference in every-day life. Sabia claims the effects will eventually be noticeable.
Nixon did agree that the study drew attention to the fact that middle aged to older individuals should pay attention to their drinking habits but it would be fair to say that the majority of people are aware that alcohol can have adverse medical and psychological effects.

Source; http://news.msn.com/science-technology/drinking-linked-to-faster-mental-decline-in-men