A family study of lithium-responsive psychosis.

Psychiatric life histories of 487 first-degree family members of 24 lithium-responsive (mood-incongruent) psychotics, 54 lithium-nonresponsive (mood-incongruent) psychotics, and 18 lithium-responsive patients with bipolar (manic-depressive) disorder were contrasted. While the morbid risk of schizophrenic-spectrum was 11.1% in relatives of lithium-nonresponsive probands, the morbid risk for such disorders was only 2.4% in relatives of lithium-responsive (mood-incongruent) psychotics (P less than 0.05). This lithium-responsive illness appears to be familially, and perhaps genetically, distinct from the bulk of the schizophrenias.