Mood-incongruent versus mood-congruent psychosis: differential antipsychotic response to lithium therapy

The authors previously reported that a subgroup of schizophrenic-like patients respond favorably to lithium (Li) therapy, as do patients with a classical manic illness. In the present study, the time course of psychotic and affective symptom remission after Li therapy was examined in these two groups of patients. Li responsive patients with a mood-incongruent psychosis (schizophrenic-like illness) demonstrated a rapid antipsychotic response to Li therapy, showing a 50% improvement during the first 7 days, while no improvement in affective symptoms was seen until week 2 or 3 of treatment. Alternatively, patients with a mood-congruent psychosis (where mania is the primary diagnosis) demonstrated no antipsychotic response to Li therapy during the first 2 weeks of treatment, while some improvement in manic symptoms occurred during treatment week 2. The present study demonstrates that Li therapy differentially affects psychotic symptoms in mood-incongruent as opposed to mood-congruent psychosis. Further, the growth hormone (GH) response to apomorphine administration differentiated these two groups of Li responsive patients. Patients with a Li responsive mood-incongruent psychosis demonstrated over a seven-fold greater GH response than mood-congruent psychotic patients. The present data suggest that mood-incongruent and mood-congruent psychoses may represent two biologically distinct psychotic processes separable by both medication response and central dopamine function.