A pilot genetic study of the continuum between compulsivity and impulsivity in females:: The serotonin transporter promoter polymorphism

According to some authors the obsessive-compulsive (OC) spectrum includes on one extreme, the obsessive-Compulsive Disorder (OCD) and on the other extreme the most impulsive behaviors. This is a controversial idea and other authors define the OC spectrum in different ways. The serotonin transporter (5-HTT) gene is one of the main genes that control serotonergic function. A polymorphism in the promoter area of this gene classifies subjects with low expression as S individuals (s/s or s/l) and subjects with high expression as L individuals (1/1). This polymorphism was studied in female OCD patients (n=24), non-impulsive controls (n=112) and impulsive suicidal patients (n=118) to support the OC spectrum hypothesis from a genetic perspective. A linear association exists among the serotonin transporter promoter functional genotypes (S versus L individuals) (chi(2) linear by linear association = 8.9; df = 1; p = 0.003). The frequency of S individuals (s/l or s/s) was lowest in OCD (54%, 13/24); intermediate in non-impulsive controls (71%, 80/112) and highest in impulsive suicide attempters (82%, 96/117). More importantly, future studies need to consider that genetics may be related to behavioral dimensions (compulsivity to impulsivity) instead of to specific psychiatric disorders defined in clinical terms. (C) 2005 Elsevier Inc. All rights reserved.