Depression with psychotic features is influenced by the polymorphism of the serotonin transporter gene

Abstract Introduction Current diagnostic classifications regard psychotic symptoms during depressive episodes as indicators of depression severity. However, growing evidence suggests that depression with psychotic symptoms (MDP) may represent a distinct subtype of depression. In the course of the search for discriminating factors we tested the hypothesis that the serotonin transporter gene (5-HTTLPR) may interact with the manifestation of psychotic symptoms in acute depression. Methods 112 inpatients (61 female) with a depressive episode (16 bipolar, 86 unipolar) at admission were genotyped for 5-HTTLPR variants. Psychotic symptoms und general psychopathology were evaluated comprehensively using the Manual of the Association for Methodology and Documentation in Psychiatry ( Arbeitsgemeinschaft fur Methodik und Dokumentation in der Psychiatrie, 1981 ). For statistical analysis a chi-square test and a logistic regression model was used. Results 16 (14.3%) out of 112 patients were currently presenting with psychotic symptoms. The primary finding of our study was the higher prevalence of the s-allele of the 5-HTTLPR within the group of MDP patients (Pearson χ ²=7.87; df=2; p χ ²=6.5; df=1; p =0.01). This effect was even more pronounced upon comparing only severely depressed patients with MDP patients. From a psychopathological perspective, MDP patients showed higher AMDP hostility and apathy scores but equal AMDP depression scores. Discussion This is the first study to show an influence of 5-HTTLPR on psychotic symptoms in acutely depressed patients. Limitations The lack of a control group and the relatively small sample size limits the present study's findings, thus replication in a larger sample is necessary.