Assessment of serotonin transporter binding in suicide attempters using PET and [¹¹C]DASB

Objectives Abnormal serotonin transporter (SERT) function is thought to play a role in the pathophysiology of suicidal behavior. And previous studies have implicated the striatum in suicidal behavior. In the present study, we compared striatal SERT binding between the suicide attempters (SA) and control subjects (NC) using PET and [¹¹C]DASB.

Methods NC and SA underwent PET scanning after intravenous injection of [¹¹C]DASB (injected dose = 756.3 ± 111.1 MBq) to quantify in vivo cerebral SERT binding. The SERT binding potential (BP_ND) of [¹¹C]DASB was calculated by use of a multilinear reference tissue model with the cerebellum as a reference region. Volumes of interest were defined on each subject’s brain MRI. The striatum was subdivided into the limbic, associative and sensorimotor subregions.

Results SA had increased SERT BP_ND in the limbic (14.8%, P = 0.0237), associative (11.7%, P = 0.3419) and sensorimotor (13.7%, P = 0.2278) subregions of the striatum compared to NC. Furthermore, midbrain SERT BP_ND was significantly positively associated with the associative (r = 0.64, P = 0.05), limbic (r = 0.70, P = 0.02) and sensorimotor (r = 0.67, P = 0.03) subregions of the striatum in NC, but those correlations were not significant in SA.

Conclusions Our data demonstrated that SA had increased SERT function in the limbic striatum, involved in emotional and motivational aspect of behavior, and also indicate an impaired relationship in SERT function between midbrain and striatum in SA. These results may help understand neurobiological substrates of SA, regardless of psychopathologies such as depression and bipolar disorder.