Diminished brain 5-HT transporter binding in major depression: A positron emission tomography study with [¹¹C]DASB

Background: The serotonin transporter (5-HTT) plays a critical role in the regulation of serotonin neurotransmission and has been implicated in the pathophysiology of major depression. In a previous positron emission tomography study, we found no difference in brain 5-HTT binding between unmedicated recovered depressed patients and healthy controls. Aim: This study aims to assess brain 5-HTT binding in a group of unmedicated acutely depressed patients in comparison to healthy controls. Methods: We studied 5-HTT binding using [¹¹C]DASB in conjunction with positron emission tomography in 12 medication-free depressed patients with a mean duration of illness of about 1 year and 24 healthy controls. Results: The depressed patients had lowered 5-HTT binding in several brain regions including brain stem, thalamus, caudate, putamen, anterior cingulate cortex and frontal cortex. Conclusions: These results suggest that diminished availability of the 5-HTT in the brain may be a state marker of acute depression. Alternatively, low 5-HTT binding may delineate a group of depressed patients with a poor long-term prognosis.