Dopaminergic Drugs Modulate Resting-State EEG Microstates in Healthy Participants.

Changes in the temporal parameters of EEG microstates are observed in various psychiatric illnesses, including psychotic disorders. These changes have also been observed in individuals with a clinical or genetic high risk for psychosis. It is unclear whether dopamine abnormalities, distinctive of psychotic disorders, contribute to microstate alterations. Fifty-eight healthy participants (M: F = 32:26) took part in a single-dose drug challenge study. Using a randomized, double-blind, cross-over, and placebo-controlled design, participants received the dopamine precursor L-DOPA (100 mg), the dopamine antagonist haloperidol (2 mg), and a placebo. Resting-state (10 min, eyes-closed) 64-channel EEG was recorded at peak drug effects. We calculated temporal parameters (coverage, duration, and occurrence) of 5 microstate classes (A-E) and compared them between drug conditions using linear mixed-effect models. Significant group x class interactions were observed for all parameters. Compared to placebo, parameters of microstate B were decreased under L-DOPA (duration and occurrence) and haloperidol (coverage, duration, and occurrence). Coverage and occurrence of microstate C were reduced under L-DOPA compared to haloperidol and placebo. Parameters of microstate E were reduced under L-DOPA compared to haloperidol (coverage and occurrence) and placebo (coverage, duration, and occurrence). Both haloperidol and L-DOPA increased all parameters of microstate D, compared to placebo. Our results show that resting-state EEG microstates are modulated by dopaminergic drugs. However, extrapolations from healthy controls to patients with psychotic disorders are complicated by various factors. Further studies should investigate the (long-term) effects of haloperidol and other antipsychotics on EEG microstates in patients with psychotic disorders.