Background and aim: Many studies show high prevalence of affective disorders in obese patients. Affective temperament is a subclinical manifestation of such conditions. The 5-HTT gene encoding the serotonin transporter may be involved in both mood and eating dysregulation. The aim of this study was to investigate the influence of a polymorphism in the 5-HTT gene on affective temperament types, depressive symptoms and Body Mass Index (BMI) in obese patients.

Methods: This study involved 390 patients (237 females, and 153 males) with obesity. The TEMPS-A questionnaire, Beck Depression Inventory (BDI) and Hamilton Depression Rating Scale (HDRS) were used to evaluate affective temperaments and prevalence of depression. DNA was obtained for serotonin transporter gene-linked polymorphism (5-HTTLPR) genotyping.

Results: In obese patients S/S genotype was associated with depressive and L/L with cyclothymic temperament. Subjects with L/L genotype presented significantly higher BMI and greater intensity of depressive symptoms in BDI and HDRS. Females scored higher in anxious and depressive, while males in hyperthymic, cyclothymic and irritable temperaments. Females scored higher in BDI (subjective depression) while males in HDRS (objective depression).

Limitations: TEMPS-A, BDI and HDRS are frequently used in studies on affective disorders. However, these methods do not examine all dimensions of mood and personality.

Conclusions: In obese patients S allele of 5-HTTLPR was associated with development of depressive temperament while L allele corresponded with greater obesity and prevalence of depression. Different mechanisms may be involved in manifestation of depression in males and females with obesity.