Motor inhibition and cognitive flexibility in obsessive-compulsive disorder and trichotillomania.
OBJECTIVE
Problems with inhibiting certain pathological behaviors are integral to obsessive-compulsive disorder (OCD), trichotillomania, and other putative obsessive-compulsive spectrum disorders. The authors assessed and compared motor inhibition and cognitive flexibility in OCD and trichotillomania for the first time, to their knowledge.


METHODS
The Stop-Signal Task and the Intradimensiona/Extradimensional Shift Task were administered to 20 patients with OCD, 17 patients with trichotillomania, and 20 healthy comparison subjects.


RESULTS
Both OCD and trichotillomania showed impaired inhibition of motor responses. For trichotillomania, the deficit was worse than for OCD, and the degree of the deficit correlated significantly with symptom severity. Only patients with OCD showed deficits in cognitive flexibility.


CONCLUSIONS
Impaired inhibition of motor responses (impulsivity) was found in OCD and trichotillomania, whereas cognitive inflexibility (thought to contribute to compulsivity) was limited to OCD. This assessment will advance the characterization and classification of obsessive-compulsive spectrum disorders and aid the development of novel treatments.
Chamberlain
Samuel R
SR
Department of Psychiatry, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Box 189, Cambridge, UK. src33@cam.ac.uk
Fineberg
Naomi A
NA
Blackwell
Andrew D
AD
Robbins
Trevor W
TW
Sahakian
Barbara J
BJ
D000328:Adult; D001288:Attention / Q000502:physiology; D003072:Cognition Disorders / Q000175:diagnosis*; D003192:Compulsive Behavior / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis*; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D014256:Trichotillomania / Q000175:diagnosis*