Stability of set-shifting and planning abilities in patients with schizophrenia

Patients with schizophrenia have deficits in executive function that involve attentional set-shifting and planning ability. It is unclear, however, whether such deficits are stable during the course of the illness or if they fluctuate in response to medication effects or symptom changes. Patients with a DSM-IV diagnosis of schizophrenia (n=28) and healthy control subjects (n=17) were tested on computerised measures of attentional set-shifting and planning at baseline and 9-month follow-up. The measures used were the Intra/Extradimensional Shift test (ID/ED) and the Stockings of Cambridge test (SoC) from the Cambridge Automated Neuropsychological Testing Battery (CANTAB). On both tests, the patients were poorer than controls at baseline; however, there was no evidence of change over the 9-month follow-up. Additionally, there was little evidence of a relationship between executive test performance and medication or length of illness. This study accords with the presence of executive processing deficits in schizophrenia that are stable across time.