Serotonin transporter polymorphism, depressive symptoms, and emotional impulsivity among advanced breast cancer patients

Purpose: This study tested a theory linking a marker of low serotonergic function to both depression and impulsivity in a sample of advanced breast cancer patients, among whom elevated depressive symptoms and difficulty regulating emotions are commonly reported.

Methods: A total of 95 patients provided blood samples for serotonin transporter polymorphic region of the gene (5-HTTLPR) and completed questionnaires that measured depressive symptoms and emotional impulsivity.

Results: Structural equation modeling revealed that the s allele of 5-HTTLPR was related to greater depressive symptoms (β = .20, p < .042) but only marginally to greater emotional impulsivity (β = .19, p < .068). Depressive symptoms and emotional impulsivity were positively related (β = .33, p < .003). Further tests explored possible mediation from genotype to one psychological variable via the other. Results suggest that depressive symptoms, particularly perceived interpersonal rejection, may be a pathway linking genotype to emotional impulsivity.

Conclusions: Findings provide the first evidence that low serotonergic function contributes to both depression and impulsivity within a clinically meaningful sample. Furthermore, the link of s allele of 5-HTTLPR to emotional impulsivity was mediated by depressive symptoms, particularly perceptions of social rejection. Findings have implications for advanced breast cancer patients' treatment decision.