Background: Cognitive predictors of relapse have been extensively explored only in few long term longitudinal studies of first-episode schizophrenia.
Method: This study prospectively followed 93 patients with first-episode schizophrenia, schizophreniform disorder, and schizoaffective disorder for 3 years after their first-episode illness. Cognitive domains including verbal intelligence, verbal and visual memory, verbal fluency, and Wisconsin Card Sorting Test performance were investigated as potential predictors of relapse.
Results: We found that by the first year 21% patients had relapsed, by the second year 33% had relapsed, and by the third year 40% had relapsed. There was a significant difference in the relapse rate between patients with good adherence and patients with poor adherence to medication regimes. A multiple logistic regression analysis revealed that after controlling for medication adherence, perseverative error in the Wisconsin Card Sorting Test was the only cognitive function that significantly predict relapse with an odds ratio of 2.4.
Conclusions: Cognitive flexibility in set shifting is related to tendency towards relapse in first-episode schizophrenic patients. Other cognitive factors appear not to be related to relapse. Possible mechanisms included the link between prefrontal dysfunction and sub-cortical dopamine system stability, as well as the effects of executive dysfunction on insight impairment and adherence behavior.