The relationship between two intermediate phenotypes for alcoholism: low voltage alpha EEG and low P300 ERP amplitude

There is considerable evidence that the amplitude of the heritable P300 event-related potential (ERP) is reduced in alcoholics and their alcohol-naive children. Low voltage alpha (LVA), a heritable resting electroencephalogram (EEG) trait present in 7-14% of the population, has been shown to be associated with alcoholism and anxiety disorders. A few studies have demonstrated a modest correlation between pre-stimulus alpha power and P300 amplitude. We aimed to test this finding in community volunteers, hypothesizing that LVA would be associated with low P300 amplitude.

Digitized resting EEG was recorded at the central parietal site (Pz) from 85 male and 113 female community volunteers (120 unrelated). ERPs were elicited at Pz by auditory and visual oddball paradigms. All participants were interviewed with the Schedule for Affective Disorders, Lifetime Version (SADS-L) and assigned blind-rated psychiatric diagnoses according to the American Psychiatric Association DSM-III-R criteria.

LVA participants (including alcoholics and nonalcoholics) had significantly lower auditory and visual P300 amplitudes. Absolute alpha power was modestly correlated with auditory and visual P300 amplitude and was associated with 9.4% and 4.6% of the variance, respectively.

The association between LVA and low P300 amplitude, two distinct electrophysiological traits, suggests that, at least in individuals with the LVA trait, some aspects of resting, unstimulated brain activity and activated brain function in the form of attentional response may be fundamentally related.