The Mediating Effect of Psychological Distress on the Association between BDNF, 5-HTTLPR, and Tinnitus Severity

Abstract

Objective To investigate the association between genetic polymorphisms of brain-derived neurotrophic factor (BDNF) or serotonin transporter gene-linked polymorphic region (5-HTTLPR) and tinnitus, and the mediating effects of psychological distress on this association.Methods Eighty-six patients experiencing tinnitus and 252 controls were recruited. The Tinnitus Handicap Inventory was used to assess the severity of tinnitus and the Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory-II (BAI-II), and the Korean version of the Brief Encounter Psychosocial Instrument (BEPSI-K) were used to assess psychological distress. We compared the association of <i>BDNF</i> rs6265 (Val66Met) and <i>5-HTTLPR</i> variants in the two groups. The mediating effects of BDI-II, BAI-II, and BEPSI-K were examined using multiple regression analysis and validated by the Sobel test and bootstrapping.Results No significant differences were found between the groups regarding <i>BDNF</i> Val66Met and <i>5-HTTLPR</i>, but the <i>5-HTTLPR</i> variants trended toward association. Depressive symptoms appeared to act as a mediator on the relationship within the <i>5-HTTLPR</i> s/s genotype and the severity of tinnitus.Conclusion Our findings provide a speculative idea on the association between the serotonergic system and tinnitus and suggest that depressive symptoms act as a mediator in tinnitus. Therefore, screening for depressive symptoms in patients with tinnitus is essential and intervention for depressive symptoms may help alleviate the severity of tinnitus.