Association of serotonin transporter (SERT) availability and body mass index (BMI) in healthy Europeans

Objectives Serotonin-mediated mechanisms are thought to have an effect on food intake and may play a major role in the pathophysiology of obesity. First PET studies indicate that SERT (i) contribute to the efficacy of the appetite-suppressing drug sibutramine (Talbot et al. Neuropsychopharmacol 2009), (ii) are correlated with the BMI (Erritzoe et al. Neuroimage 2010, Hesse et al. EJNMMI Suppl 2009) as a measure of obesity. However, studies on the latter were contradictory. Thus, the aim of the study was to further test whether SERT and BMI are inter-related in a larger cohort of healthy subjects.

Methods We included 127 subjects out of the ENC DAT database of normal [¹²³I]FP-CIT SPECT (57 females, age 52±19y, range 20-83y). ROI analysis (MultiModality, Hermes) of the SPECT scans coregistered with the individual MRI to calculate [¹²³I]FP-CIT binding potential (BP) in the midbrain/brainstem as SERT-specific target region (Booij et al. JNM 2007). Spearman rank correlations were applied to test for an association between BMI, age and SERT availability.

Results BMI was similar in women and men (25±4, 19-38, v. 26±4, 18-41; p=.12). Age showed no relationship with BP (r=-.03, p=.77). Furthermore, BP in females did not significantely differ from those of males (1.12±.49 v 1.15±.46, p=.67) but there was a positive association between midbrain BP and BMI (r=.18, p=.03). Interestingly, when correcting for age, the correlation was even more significant (r=.25, p=.005). No significant effect of gender was found in this sample.

Conclusions The data corroborate own previous DASB PET findings of a positive correlation between BMI and SERT availability (Hesse et al. EJNNMI Suppl 2009). However, variation of midbrain BP is high requesting higher number of subjects.

Research Support EANM Research Lt