Persistent suppression of postexercise facilitation of motor evoked potentials during alternate phases of bipolar disorder.

The current study sought to longitudinally evaluate the postexercise facilitation of motor evoked potentials (MEP) in two patients during different phases of short-circle depressive-manic disorder. Each study included 50 baseline MEP elicited by transcranial magnetic stimulation, followed by 50 MEP immediately after nonfatiguing exercise of the examined muscle. Postexercise MEP facilitation, expressed as percentage of baseline value, varied from 71% to 119% and from 99% to 107% in each patient, respectively, being significantly lower than our mean normal control value (268%). No differences in MEP facilitation between phases of short-circle depressive-manic disorder were revealed. Reduced postexercise facilitation was independent of the bipolar disorder phases, suggesting an invariable underlying association of the psychiatric pathophysiological mechanisms to impaired cortical excitability.