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Neuropsychological evidence for frontostriatal dysfunction in schizophrenia
R Elliott1, P J McKenna, T W Robbins
1Department of Experimental Psychology, University of Cambridge.
Psychological Medicine
|May 1, 1995
Summary
Schizophrenia patients exhibit significant deficits in attentional set-shifting, specifically in the perseveration aspect of executive function. This impairment suggests frontostriatal dysfunction, even in individuals with preserved intelligence.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Psychiatry
Background:
- Attentional set-shifting is a key executive function.
- Frontal lobe dysfunction is implicated in various neurological and psychiatric disorders.
- The Wisconsin Card Sort Test (WCST) assesses executive functions, including set-shifting.
Purpose of the Study:
- To investigate attentional set-shifting abilities in individuals with schizophrenia.
- To determine if deficits in set-shifting are specific to certain components of executive function.
- To explore the relationship between set-shifting impairments and frontostriatal dysfunction in schizophrenia.
Main Methods:
- A computerized attentional set-shifting test, analyzing the Wisconsin Card Sort Test (WCST), was administered.
- Participants included chronic medicated schizophrenics (N=32) and age/IQ-matched controls (N=24).
- The test included 'perseveration' and 'learned irrelevance' conditions assessing extra-dimensional shifting.
Main Results:
- Schizophrenia patients showed significant impairment in the 'perseveration' condition compared to controls.
- No significant impairment was found in the 'learned irrelevance' condition.
- These deficits persisted even in a subgroup of patients with preserved IQ and did not correlate with Mini-Mental State Examination or memory scores.
Conclusions:
- Schizophrenia is associated with a specific deficit in the perseveration component of attentional set-shifting.
- These findings support the hypothesis of frontostriatal dysfunction in schizophrenia.
- Executive function impairments in schizophrenia are not fully explained by general cognitive decline or memory deficits.