Blackouts have long been associated with alcoholism. Blackouts are periods of memory loss during a period when a person has been drinking. Alcohol has only a minimal impact on the ability to remember information learned before becoming intoxicated or on keeping information active in memory for short periods of time.  

Alcohol has far reaching effects on many areas of the brain. When you consume alcohol, the body immediately begins to break it down. In the process, breakdown products called ethyl esters speed the movement of positively charged potassium ions from brain cells through the outer membranes, creating a negative charge within the cell. This impairs calcium channels, which brain cells rely upon to communicate with other cells throughout the body. The brain also receives less oxygen when alcohol is present. Alcohol also has a detrimental effect upon the central nervous system. The cumulative effect of these changes is that the activity of the hippocampus is disrupted. Moderate doses of alcohol disrupt the acquisition and performance of spatial reference memory tasks, and reduce the overall level of glutamate released at synapses within the hippocampus.