Event-related oscillations versus event-related potentials in a P300 task as biomarkers for alcoholism.

OBJECTIVE

It has been proposed that event-related oscillation (ERO) measures of EEG activity recorded in P300 tasks provide more powerful biomarkers of alcoholism than event-related potential (ERP) measures. This study examines this question in a group of long-term abstinent alcoholics (LTAAs).

METHODS

EEGs were recorded on 48 LTAAs and 48 age and gender-matched nonalcoholic controls (NACs) during the performance of a 3-condition visual target detection task. The event-related data were analyzed to extract ERP amplitude measures and total and evoked ERO power measures. Data were analyzed using multivariate analysis of covariance to determine the contributions of ERO versus ERP measures to discriminate between the LTAA versus NAC groups.

RESULTS

The LTAA group showed significantly lower evoked delta ERO power and total delta and theta ERO power compared to the control group. The evoked and total ERO power measures provide an alternative (but not more powerful) representation of the group difference than does P3b amplitude. There was a weak suggestion that nonphase-locked theta ERO power (which contributes to total ERO power) might provide independent discriminatory information.

CONCLUSIONS

Reduced evoked ERO power in the response to target stimuli provided an alternative and comparable representation of the reduced P3b amplitude in LTAA. This is not surprising as the evoked ERO power measures are derived from time-frequency representations of the ERP waveform. Induced theta oscillations might provide independent discriminatory information beyond ERP amplitude measures, but separate analysis of the event-related nonphase-locked activity is required to investigate this further.