Plasma norepinephrine responses to cold challenge in depressed patients and normal controls

Thirty depressed patients were compared with 39 controls for their plasma norepinephrine (NE) levels in relation to a cold challenge (placing a hand in ice cold water for 1 minute). Depressed patients showed significantly higher plasma NE levels than controls. Unipolar, but not bipolar patients, had significantly higher plasma NE levels than age- and sex-matched controls. Unipolar melancholic patients who were nonsuppressors on the dexamethasone suppression test showed a strong trend to have higher plasma NE levels than suppressors. These results are further evidence that the NE system is dysregulated in depression.