Alcohol’s Effect on Memory

Q. In reference to alcoholic blackouts, is it possible to be stone sober and not remember an event or conversation later? In other words, does the alcohol affect the alcoholic’s memory even when he is sober or does the amnesia always occur because of alcohol consumption at the time of the forgotten incident? I have told my alcoholic client something when he is sober, and a day later, he has no recollection of the conversation whatsoever. This is not just the typical “just plain not listening” sort of thing. It can be a very serious, lengthy conversation that he forgets. Just wondering if something else could be going on neurologically, besides the alcohol.
A. The answer is: absolutely, something else could be going on neurologically, depending on your client’s age, medical history, and prescribed or non-prescribed medications or drugs.

First, there is considerable evidence of the direct, toxic effects of alcohol on the brain (see W.A. Lishman, Organic Psychiatry, 3d ed., 1998). Even in the absence of nutritional deficiencies (e.g., thiamine deficiency inWernicke- Korsakoff syndrome), alcohol causes alterations in dendritic morphology in the hippocampus (an important center for memory), and inhibits the normal, reactive sprouting of dendrites in response to brain injury. These phenomena could account for some memory impairment in alcoholic individuals who continue to drink heavily from time to time.

Then there is Wernicke- Korsakoff syndrome (WKS) itself. This may present as short-term memory impairment, quiet global confusion, mild delirium, or confabulation. Typically, WKS would also show neurologic features, such as gait abnormalities and impaired eye movements.

Regarding alcoholic blackouts: an alcoholic blackout is a period of severe amnesia for events that occurred during a drinking episode, even though the person’s outward behavior at the time was not grossly abnormal. Usually the memory gap extends for several hours, but may extend for days. The individual may have carried out activities and conversations fairly normally during the period of amnesia, but has no memory of these events afterwards. While early studies suggested that blackouts can occur even after small or medium amounts of alcohol, prior to real addiction, most recent data show that blackouts are directly associated with the severity and duration of alcoholism. They usually appear only late in the course of the illness, and well after physical dependence and loss of control have become established. There seems to be an association between alcoholic blackouts and a prior history of head injury [see WA Lishman, Organic Psychiatry, 3d edition, for details]. In some cases, it may be the sudden rise in blood alcohol levels, rather than the absolute amount, that triggers a blackout.For more details, you might want to see the study by Anthenelli et al, in Journal of Studies in Alcoholism [J Stud Alcohol] May 1994.

I would suggest that you have your patient evaluated neurologically, including, if possible, some neuropsychological testing and brain imaging. I would also carefully investigate if he might be using other street drugs (? marijuana ?opiates) besides alcohol that might be impairing his memory. And, particularly if he is elderly, all the usual culprits (such as Alzheimer’s Disease, small strokes, B12 or folate deficiency, etc.) must be ruled out

This information is not intended to be a substitute for professional medical advice. You should not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider. Please consult your healthcare provider with any questions or concerns you may have regarding your condition.

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