Cognitive flexibility and complex integration in Parkinson's disease, Huntington's disease, and schizophrenia

Two new tasks designed to individualize and assess aspects of cognitive flexibility and complex integration were administered to patients with schizophrenia (n = 16), Parkinson's disease (PD; n = 25) and Huntington's disease (HD; n = 12). Findings indicated impaired performance in the schizophrenic and HD groups on components of solution fluency, reactive flexibility and integration. The PD group demonstrated normal performance on all but the solution fluency and reaction time measures. These findings corroborate previous studies suggesting that executive and problem solving disturbances feature in schizophrenia and HD and that these functions may not be as severely affected in medicated PD. Slowed reaction time by both dementia groups is explained with reference to the concept of bradyphrenia.