Platelet monoamine oxidase activity and behavioral response to pharmacotherapy in psychiatric patients

Platelet monoamine oxidase (MAO) levels were determined for drug-free psychiatric inpatients who were subsequently treated with neuroleptics, tricyclics, or lithium. Weekly, time-sampled recordings of specific behaviors were also made during both drug-free and medication periods. Significant correlations were obtained between MAO levels and changes in behavior scores subsequent to drug administration. For six of the seven recorded behaviors, correlations for patients treated with lithium vs. tricyclics were in the opposite direction. The results suggest that MAO levels, measured during a drug-free period, can predict some of the behavioral responses to antidepressant medications.