CSF substance P immunoreactivity in affective disorders

CSF substance P immunoreactivity was determined in a group of inpatient controls and acutely manic, euthymic, or depressed unmedicated unipolar and bipolar subjects; a second outpatient group of euthymic bipolar patients (on and off lithium) and normal volunteers was also studied. No group differences and no lithium effects were detected. CSF that was allowed to stand at room temperature for brief periods and then was refrozen contained elevated levels of the immunoreactive substance P, an observation that may account for a previous report of elevated CSF substance P immunoreactivity in psychiatric disorders.