Psychosis, lithium-induced antipsychotic response, and seasonality.

Lithium alone has previously been shown to effect antipsychotic response in approximately one-quarter of mood incongruent psychoses. Such lithium-responsive psychoses and/or the antipsychotic effects of lithium appear to be seasonal, with maximal response rates occurring in the 3-month periods surrounding January and July peaks. Within patients, retrials of lithium in formerly lithium-responsive psychotic patients demonstrate a trend toward greater continued antipsychotic effects of lithium during the periods surrounding January and July (80% response rates) vs. the remaining 6 months of the year (33% response rates).