Background: Schizophrenia is preceded by basic symptoms which may persist after long time and include subjective cognitive impairment. Furthermore, it is characterised by cognitive deficits that may deteriorate with the progression of illness. To examine the relationship between neurocognition and basic symptoms along the course of schizophrenia, we compared the cognitive performance and the basic symptoms of one population with first episode psychosis (FEP) and one with a chronic, multi-episode course (MEP).
Methods: We tested 8 FEP (5 male) and 7 MEP (7 male) in- and outpatients, for basic symptoms with the Schizophrenia Proneness Instrument-Adult version (SPI-A) and for neurocognition with Raven's Color Progressive Matrices (CPM), Rey-Osterrieth's complex figure (Rey), Corsi's and Buschke-Fuld tests, the Wisconsin Card Sorting Test (WCST), the Stroop test, and the Trail Making Test (TMT).
Results: FEP patients did not differ from MEP patients as for SPI-A scores. MEP patients were significantly more impaired on several subtests of Buschke-Fuld, the Rey, and the WCST with respect to FEP. Impairment on the cognitive subscale of the SPI-A correlated with non-perseverative WCST errors, and on the self subscale of the SPI-A with impaired performance on the Buschke-Fuld. Further, in MEP, impairment on the body subscale of the SPI-A correlated inversely with number of categories completed of the WCST.
Conclusions: Basic symptoms persist throughout the phases of schizophrenia and are relatively independent of cognitive performance. A chronic, multi-episode course is associated with increased cognitive impairment in schizophrenia.