PET brain imaging with [11C](+)McN5652 shows increased serotonin transporter availability in major depression.

BACKGROUND

Alterations in the brain serotonin (5-HT) system have been found in patients with depression. We used the selective 5-HT transporter site ligand 11CMcN5652 and positron emission tomography (PET) to examine the hypothesis that alterations in 5-HT transporter levels may be present in selected regions of the brain in depressed patients.

METHODS

Four drug free depressed patients and four healthy control subjects were studied using 11CMcN5652 and PET. The distribution volume (DV) ratio of the PET ligand in selected regions of interest (ROIs) compared to cerebellum were calculated for the ROIs.

RESULTS

Patients showed significantly larger DV ratios in the left frontal cortex (P=0.013) and right cingulate cortex (P=0.043) compared to control subjects.

LIMITATION

The sample size was modest with gender differences between the subject groups. The PET agent, 11CMcN5652, may have a lower binding affinity for the 5-HT transporter in the cortical regions compared to other brain regions.

CONCLUSION

These findings suggest that 5-HT transporter sites may be increased in the frontal and cingulate cortices of depressed patients. These alterations in 5-HT transporter sites may be of pathophysiologic significance in the etiology of depression and its treatment.