The cognitive deficits associated with schizophrenia have received increasing attention as potential endophenotypes of the disorder that could potentially discriminate relatives of patients from controls. Endophenotype that is inherited and state – independent should be found in affected family members as well as in nonaffected family members at a higher rate than in the general population.
The current study has attempted to characterize the prevalence, degree and nature of verbal memory deficit in schizophrenia and aimed to study verbal memory task performance in patient with paranoid schizophrenia and their first degree relatives in order to identify, trait cognitive marker of the disorder. Due to this we had studied, whether nonpsychotic relatives of schizophrenic probands had an elevated risk of deficits in cognitive functioning, and, which specific factors such as gender, age, education, illness duration, diagnosis and psychopathological symptoms influenced the tests performance.
Schizophrenia patients showed significant impairment of the verbal memory in all domains. In contrast, their first degree relatives having the same education level as the patients did not differ considerably from healthy controls. These results indicate that, probably, the deficiency of explicit verbal memory is not associated with the diathesis for schizophrenia.
As the test performance did not correlate with severity of symptoms and medication this finding cannot be attributed to the distractibility due to active psychotic symptoms, or treatment effects. Impaired performance on the CVLT task, a measure of explicit verbal working memory, appears to be associated with the cognitive deficits due to the disorder itself.