Electrophysiological evidence of memory impairment in alcoholic patients.

In a series of event-related potential (ERP) studies, we have consistently demonstrated an ERP component correlate of visual short-term memory. There have been frequent reports on the deficits of information encoding, retention, and retrieval in chronic alcoholics. In the present study, we investigated that the ERP mnemonic effects could be influenced by long-term alcohol abuse. ERP data were recorded from 48 controls and 77 alcoholics while the subjects performed a modified delayed matching to sample paradigm using a series of object pictures as stimuli. The alcoholics completed the task with more errors and longer response times than the controls. The major differences in the evoked potentials between the two groups are found at the temporo-occipital and frontal regions in the sample and nonmatching trials, and mostly prominent in the right hemisphere. The current study indicates that the ERP technique can be a useful tool to index short-term memory. The ERP mnemonic effect difference between the two groups may be a reflection of a working memory deficit caused by long-term alcohol abuse. Our data also suggest right hemisphere dysfunction in alcoholics, with deficits in information encoding.