Cognitive impairment of executive function as a core symptom of schizophrenia

Abstract

Cognitive dysfunction is a common finding in schizophrenia. Nevertheless the specific pattern of neuropsychological impairment in schizophrenia compared to other severe mental illnesses has not been intensively studied. Twenty-four patients with schizophrenia belonging to different stages of the disease (11 first-episode patients, 13 patients with multiple episodes), 18 patients with bipolar disorder and 23 healthy control subjects underwent standardized neuropsychological assessment. Statistical analysis of covariance (ANCOVA) demonstrated that, compared to control subjects, patients with schizophrenia performed significantly worse in the trail-making test (P = 0.012), verbal fluency (category letter, P = 0.004), verbal learning/memory (P = 0.005), and the Wisconsin Card Sorting Test (WCST) (P = 0.004 for administered trials; P = 0.025 for perseverative responses, T value) indicating significant deficits in attention and psychomotor performance, and in particular in verbal working memory and cognitive flexibility for schizophrenic patients. A significant difference between schizophrenic and bipolar patients was found only in the WCST. Schizophrenic patients made significantly more perseverative responses (P = 0.002, ANCOVA), indicating a more pronounced and specific deficit in cognitive flexibility and frontally based executive function. In conclusion, these results may suggest a cognitive endophenotype in schizophrenia and underline the role of the prefrontal cortex in schizophrenic pathophysiology.

Leukocyte telomere length: Effects of schizophrenia, age, and gender

“…Severity of depressive symptoms was assessed with the Calgary Depression Rating Scale (CDRS; Addington et al, 1990). Assessment of cognitive functioning was focused on executive functioning composite score (Delis et al, 2001;Fucetola et al, 2000;Wobrock et al, 2008).…”

99mTc-ECD SPECT at rest and activation in young patients with schizophrenia

“…Impairment of executive functions in our group of patients determined by poor WCST performance is a part of cognitive dysfunction-a core feature in schizophrenia [21]. Anatomical substrates associated with functional disturbances were evaluated in the present study by means of brain perfusion SPECT with two different types of quantitative analysis; voxel-based and VOI-based.…”

Positive Traits in the Bipolar Spectrum: The Space between Madness and Genius

“…Other personality factors, such as increased sociability, strong ambition, and a desire for recognition by others, characterize those who excel because of their creative talent and are features observed in bipolar patients and their relatives, which may partially explain the tighter link of bipolar disorder to creativity compared with schizophrenia [33,83,118,131]. Additionally, the deficits in executive function in schizophrenia patients [132,133], which are primarily associated with negative symptoms, may explain the relatively poor performance of schizophrenia patients for measures of creativity involving fluency and cognitive flexibility [134,135,136]. If creativity and psychosis result from a shared vulnerability, cognitive protective factors, such as high IQ and cognitive flexibility, may lead to enhanced creativity, whereas the cognitive deficits often present in full-blown illness may prevent the individual from fully realizing their creative potential [49,115].…”