Neuropsychological Aspects of First-Episode Psychosis : Diagnosis, Course and Outcome

Sammanfattning: The present thesis is based on studies of neuropsychological functions in first episode psychosis patients (FEP) from the Swedish multicenter study, the Parachute Project. The thesis aims to clarify neuropsychological functions in psychotic illnesses. Patients from the project were examined neuropsychologically, using the WAIS-R NI test battery, in relation to measures of outcome in terms of clinical, psychological and social parameters. In the project, FEP patients were offered “need-adapted” treatment and follow up for five years, based on out-patient care in order to positively affect long-term outcome. Cognitive functions were examined shortly after onset of psychosis and significantly predicted presence of negative symptoms year one, and functional outcome years three and five. Impairments in cognition are characteristic of the acute state of the psychotic illness, and appear to be a trait feature in those patients with poor prognosis, e.g. those who later develop schizophrenia. These impairments may also be present in phases of symptoms in remission. Generally, a wide range of cognitive impairments may be present and with arge individual variation, although no specific neuropsychological profile has yet been found. Aspects of social cognition are particularly impaired in psychosis, and in the neuropsychological version of the subtest Picture Arrangement it was found that FEP patients had significantly lower results than a group of healthy control subjects, and that patients had significantly lower rates of correctly identified implied meanings of the sequenced pictures. However, no significant relationship was found between results on this test and functional outcome in year three, indicating that the impaired ability to identify subtle aspects of communication, such as implied meanings, could be regarded as a state defect in psychosis. A significant improvement of general cognitive functioning at the three-year follow up was found in almost all patients. Results on non-verbal tests were lower than on verbal tests in all patients at baseline, and the difference was more pronounced in patients with schizophrenia psychosis syndromes than in patients with nonschizophrenia psychosis syndromes. At follow up, the difference between nonverbal and verbal tests remained significant only for patients with schizophrenia syndromes. This improvement co-varied with increased global functioning and lessened psychotic symptoms. Improvement of non-verbal functions appears to be central to general improvement and is suggested to be included in the proposed remission criteria for FEP patients. In conclusion, the variety of cognitive impairments in psychosis may be best understood as a failure at the basic neural level of brain functioning, e.g. deficits in the selective and executive attentional networks. These impairments mainly represent a state effect and a trait effect in patients with a poor prognosis. This focuses on the importance of the neuropsychological examination of psychosis patients for understanding the needs and strengths of the individual, and for planning and evaluation of treatment.