Platelet MAO activity in patients with chronic pain syndrome. Relationship to personality traits, endorphins in CSF and plasma cortisol.

Platelet MAO activity was investigated in 32 healthy volunteers and 22 patients with chronic pain syndrome. The MAO activity did not differ between the healthy volunteers and the pain patients. There was a tendency for patients with low platelet MAO activity to have somewhat longer pain duration and somewhat higher pain levels but the difference was not statistically significant. Patients with low platelet MAO activity were found to have higher values on the Zuckerman sensation seeking scale, a disturbed diurnal pattern of plasma cortisol and a tendency towards lower concentrations of endorphins in CSF. It is postulated that platelet MAO activity reflects the activity of the serotoninergic part of the serotonin--ACTH--cortisol system.