Differences in serotonin transporter binding affinity in patients with major depressive disorder and night eating syndrome

OBJECTIVE: We examined serotonin transporter (SERT) binding affinity using single photon emission computed tomography (SPECT) in patients with major depressive disorder (MDD) and night eating syndrome (NES). There are similarities between MDD and NES in affective symptoms, appetite disturbance, nighttime awakenings, and, particularly, response to selective serotonin reuptake inhibitors (SSRIs). METHODS: Six non-depressed patients with NES and seven patients with MDD underwent SPECT brain imaging with 123I-ADAM, a radiopharmaceutical agent selective for SERT sites. Uptake ratios of 123I-ADAM SERT binding were obtained for the midbrain, basal ganglia, and temporal lobe regions compared to the cerebellum reference region. RESULTS: Patients with NES had significantly greater SERT uptake ratios (effect size range 0.64–0.84) in the midbrain, right temporal lobe, and left temporal lobe regions than those with MDD whom we had previously studied. CONCLUSIONS: Pathophysiological differences in SERT uptake between patients with NES and MDD suggest these are distinct clinical syndromes.