WASHINGTON, D.C.--Drs. Henri Begleiter and Bernice Porjesz, Department of Psychiatry, State University of New York Health Science Center at Brooklyn, and colleagues in the six-university Collaborative Study on the Genetics of Alcoholism (COGA)* identify in the May Electroencephalography and Clinical Neurophysiology (Volume 108, Number 3) chromosomal regions that may underlie the functional organization of human neuroelectric activity, including the event-related brain potential known as P3. Since the 1980s, when Dr. Begleiter first identified reduced P3 wave amplitude in alcohol-naive sons of alcoholics, researchers have regarded the abnormality as a potential noninvasive marker of genetic risk for alcoholism.
Event-related potentials (ERPs) are brain electrical signals produced in response to specific sensory stimuli (such as a light or a sound) that provide sensitive measures of cognitive activity. Measured at the scalp using standard electroencephalography (EEG) technology, ERPs are displayed as wave-like lines and measured according to their height (amplitude) and elapsed time following a stimulus. The P3 or P300 ERP component peaks between 300 and 500 milliseconds after a stimulus, and its amplitude is higher for significant than insignificant stimuli. Persons with low P3 amplitude are believed to have difficulty distinguishing significant from insignificant stimuli.
Previous studies repeatedly found P3 voltage to be low in several clinical conditions including schizophrenia, attention deficit disorder, and alcoholism. Although, with alcoholism, researchers initially attributed low P3 voltage to the cumulative toxic effects of alcohol, Drs. Begleiter and Porjesz in 1985 demonstrated that P3 remains low in alcoholics who have been abstinent for as long as 10 years. In 1991, another research team related low P3 amplitude to number of alcoholic first-degree relatives rather than personal drinking history. Such indications that low P3 ampl
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