In the United States, 52 percent of adults ages 18 and over are current regular drinkers, meaning they consumed at least 12 alcoholic beverages in the previous year, according to the Centers for Disease Control and Prevention. While in moderation alcohol has its benefits, too much can cause negative effects, including causing issues with memory.
Aaron M. White, Ph.D., author of “What Happened? Alcohol, Memory Blackouts, and the Brain,” explained that in regards to memory, “alcohol seems to influence most stages of the process to some degree, but its primary effect appears to be on the transfer of information from short-term to long-term storage.” This means that someone who has consumed alcohol can remember something for a short period of time, such as a minute or even more if her attention is not diverted elsewhere; however, later on in the evening, that person may not remember that new information from earlier. In cases where a person has consumed a large amount of alcohol and it has a severe impact on the transfer of information from short-term memory to long-term memory, she may not remember events that occurred. When this happens, it's called a blackout. People who experience blackouts from alcohol consumption only have trouble remembering information that occurred while they were intoxicated; these blackouts do not typically affect memories that were in storage before they began drinking. Different factors can contribute to blackouts. White noted that large quantities of alcohol, drinking on an empty stomach, and gulping drinks as factors that can lead to a blackout.
Alcohol can have direct and indirect effects on areas of the brain involved in memory. For example, White pointed out that alcohol can affect the hippocampus: damage to the CA1 region of the hippocampus affects the brain's ability to form explicit memories, a type of conscious memory involving information and experiences. Alcohol also affects long-term potentiation, which is a heightened responsiveness for neural signals. Other brain areas affected by alcohol include the frontal lobes.
Chronic alcoholism can lead to more severe memory problems. Alcohol affects the absorption of the vitamin thiamine, leading to a deficiency. The National Institute on Alcohol Abuse and Alcoholism noted that 80 percent of alcoholics have this deficiency, which can lead to the condition Wernicke-Korsakoff syndrome. The disorder is two parts: Wernicke's encephalopathy and Korsakoff's psychosis. With Wernicke's encephalopathy, symptoms include confusion, vision changes and loss of muscle coordination. When patients go on to develop Korsakoff's psychosis, they cannot form new memories, have severe memory loss, and may have hallucinations. To compensate for the memory loss, patients may make up stories, called confabulation.
References
Centers for Disease Control and Prevention. FastStats: Alcohol Use.. 2010. Web. 11 April 2011
http://www.cdc.gov/nchs/fastats/alcohol.htm
White, A.M. What Happened? Alcohol, Memory Blackouts, and the Brain. 2004. Web. 11 April 2011
http://pubs.niaaa.nih.gov/publications/arh27-2/186-196.htm
National Institute on Alcohol Abuse and Alcoholism. Alcohol's Damaging Effects on the Brain. 2004. Web. 11 April 2011
http://pubs.niaaa.nih.gov/publications/aa63/aa63.htm
MedlinePlus Medical Encyclopedia. Wernicke-Korsakoff Syndrome. 2011. Web. 11 April 2011
http://www.nlm.nih.gov/medlineplus/ency/article/000771.htm