Cognitive functioning in first episode psychosis: initial presentation
Introduction
Cognitive deficits are a core feature of schizophrenia and individuals with schizophrenia demonstrate deficits in most domains of cognitive functioning compared to both psychiatric and non-psychiatric control groups Green, 1998, Heinrichs and Zakzanis, 1998. The most notable differences are in memory, language, psychomotor processing and attention. Individuals experiencing their first episode of schizophrenia also evidence cognitive deficits that are often equivalent to those seen in patients with a more chronic course of illness Addington and Addington, 2002, Bilder et al., 2000, Hoff et al., 1992, Hutton et al., 1998, Mohamed et al., 1999. These first episode subjects have the most difficulty in areas of memory, language, attention and psychomotor processing. There are some tasks, such as the Wisconsin Card Sorting Task (WCST) on which first episode subjects have demonstrated superior performance to that of more chronically ill subjects Addington and Addington, 2002, Bilder et al., 2000, Hutton et al., 1998. In contrast, in their first episode community sample, Townsend et al. (2001) reported that first episode patients generally performed in the average range across the majority of tasks, with the exception of a speeded processing task.
The overall purpose of this study is to examine the longitudinal course of cognitive functioning and its relationship to outcome in a large community sample of first episode patients. These individuals are attending a first episode program available to the whole community, which most likely includes the majority of potential incidence cases (Addington and Addington, 2001). In this initial paper, we want to determine the range of deficits at the initial presentation and whether there are differences amongst different schizophrenia spectrum diagnostic groups.
Section snippets
Subjects
Subjects were 312 (204 men, 108 women) first episode (FE) patients who were admitted to the Calgary Early Psychosis Program (EPP), which serves an urban population of 930,000 (Addington and Addington, 2001). These individuals were experiencing their first episode of psychosis and had not received more than 3 months of previous adequate treatment (Larsen et al., 1996). Subjects were excluded from this study if they had a history of neurological disorders, head injury, epilepsy, or did not speak
Results
Z-scores were calculated for obtained scores from the FE sample using normative values. T-tests revealed that the NPCs scored significantly better on every single test compared to the FE subjects. Mean scores of the tests for both groups are presented in Table 2.
NART scores showed that the sample likely fell within the upper end of the average range for full-scale, Verbal and Performance IQs (Nelson, 1982) (see Fig. 1).
FE subjects demonstrated significant difficulty on verbal fluency, a range
Discussion
This paper has described the cognitive performance of a large sample of first episode patients in the first few months after admission to an early psychosis program. This sample includes the majority of potential incidence cases in the city of Calgary as well as a wide range of schizophrenia spectrum disorders as would be expected in a first episode sample. Our results suggest similar deficits to those seen in individuals with schizophrenia and supports existing studies reporting impaired
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