Objective: Decision-making impairment is an important feature of some psychiatric disorders, such as attention-deficit/hyperactivity disorder and substance-use disorders, and is associated with dysfunction of the fronto-subcortical circuit, mainly the orbitofrontal cortex (OFC). Several data reports support significant correlations between decision-making impairment and the serotonin system. Thus, this neurotransmission system may be a major step in some cognitive features, particularly in OCD because serotonin is associated with this disorder. Therefore, the serotonin transporter promoter polymorphism (5-HTTLPR) may be related to the modulation of these cognitive characteristics. In a sample of Caucasian OCD patients, we explored the link between decision-making and the 5-HTTLPR.
Method: We used the Iowa Gambling Task (IGT) to measure decision-making in 49 OCD patients, according to the DSM-IV criteria. All patients were submitted to Y-BOCS, BDI, BAI, the Raven Progressive Matrices, the Continuous Performance Task, and the Trail Making Test. We grouped S- and/or Lg-carriers in view of the fact that these act in a nearly dominant way.
Results: On IGT, S- and/or Lg-carriers had significantly lower scores on the third, fourth, and fifth blocks. These findings were confirmed after adjusting for clinical and cognitive variables.
Discussion: Inconclusive findings about the link between OCD and 5-HTTLPR may be better elucidated by studying OCD subgroups that could be more related in some genetic characteristics. Based on our study, low performance on IGT is associated with S- and/or Lg-carriers.
Conclusion: Our results corroborate the hypothesis that the pattern of neuropsychological functioning observed in previous studies may constitute a biological marker or heritable endophenotype of OCD.