Biochemistry and suicidal behavior in depressed patients.

The present study was undertaken in order to further explore the relationship between monoamine levels and hypothalamic-pituitary-adrenocortical (HYPAC) functioning and suicidal behavior in depressed patients. One hundred and thirty-two depressed inpatients participated in the NIMH Collaborative Study on the Psychobiology of Depression. Similar to previous reports, our suicide attempters were younger, more likely to be bipolar, had an earlier age at onset, and displayed more psychotic features. No correlation between cortisol hypersecretion or Dexamethasone Suppression Test (DST) nonsuppression and suicide attempts were found. Only the pre-DST evening plasma cortisol distinguished the groups, being lower in the attempter group. We were unable to confirm the previously reported correlation between cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) and suicide attempts. Of the monoamines examined, only urinary and plasma 3-methoxy-4-hydroxphenylglycol (MHPG) differed between suicide attempters and nonattempters, showing lower levels in the attempter group. There was a trend for CSF MHPG in the same direction. This latter reduction was restricted to the bipolar group.