ABSTRACT
BACKGROUND: Interest in the neuro-cognitive profile of patients with schizophrenia and co-morbid obsessive compulsive disorder (schizo-OCD) is rising in response to reports of high co-morbidity rates. Whereas schizophrenia has been associated with global impairment in a wide range of neuro-cognitive domains, OCD is associated with specific deficits featuring impaired performance on tasks of motor and cognitive inhibition involving frontostriatal neuro-circuitry. METHOD: We compared cognitive function using the CANTAB battery in patients with schizo-OCD (n=12) and a schizophrenia group without OCD symptoms (n=16). The groups were matched for IQ, gender, age, medication, and duration of illness. RESULTS: The schizo-OCD patients made significantly more errors on a task of attentional set-shifting (ID-ED set-shift task). By contrast, no significant differences emerged on the Stockings of Cambridge task, the Cambridge Gamble Task or the Affective Go/NoGo tasks. No correlation emerged between ID-ED performance and severity of schizophrenia, OCD or depressive symptoms, consistent with neurocognitive impairment holding trait rather than state-marker status. Schizo-obsessives also exhibited a trend toward more motor tics emphasizing a neurological contribution to the disorder.ConclusionOur findings reveal a more severe attentional set-shifting deficit and neurological abnormality that may be fundamental to the neuro-cognitive profile of schizo-OCD. The clinical implications of these impairments merit further exploration in larger studies.
Subject(s)
Neuropsychological Tests/statistics & numerical data , Obsessive-Compulsive Disorder/diagnosis , Obsessive-Compulsive Disorder/psychology , Schizophrenia/diagnosis , Schizophrenic Psychology , Adult , Affect/physiology , Aged , Attention/physiology , Comorbidity , Corpus Striatum/physiopathology , Diagnosis, Differential , Diagnosis, Dual (Psychiatry) , Discrimination, Psychological/physiology , Executive Function/physiology , Female , Frontal Lobe/physiopathology , Humans , Male , Middle Aged , Nerve Net/physiopathology , Obsessive-Compulsive Disorder/physiopathology , Psychiatric Status Rating Scales/statistics & numerical data , Psychomotor Performance/physiology , Reaction Time/physiology , Schizophrenia/physiopathology , Semantics , Young AdultABSTRACT
The association between schizophrenia and obsessive-compulsive disorder (OCD) is complex. This study systematically examined a UK cohort of clozapine-treated individuals with schizophrenia/schizoaffective disorder. Fourteen of 59 cases (24%) scored positively on item H of the Mini-International Neuropsychiatric Interview (MINI) for OCD. The mean Yale- Brown Obsessive-Compulsive Scale (Y-BOCS) score in MINI-positive cases was 17.6 (SD+/-6.3). Sixty-four percent scored 16 or more on the Y-BOCS, representing clinically meaningful illness severity. Seven (50%) patients with OCD had previously received the diagnosis by their treating clinicians and were already receiving with selective serotonin re-uptake inhibitors (SSRIs) treatment. OCD cases scored significantly worse than their non-OCD counterparts on the Abnormal Involuntary Movement Scale (P=0.01) and the Simpson Angus Scale (SAS; P=0.01). There was also a non-significant trend toward higher ratings for OCD cases on the Clinical Global Impression-Schizophrenia scale (P=0.06). Comparing the OCD cases taking SSRI (n=7) with those not on SSRI (n=7), significant differences emerged on the SAS (P=0.03). Our results suggest that OCD is common among patients receiving clozapine for schizophrenic disorders and that the comorbidity is associated with greater motoric impairment. The role of medication in this condition remains unclear.
