Defining a cognitive function decrement in schizophrenia.

Background: Although cognitive impairment is described as a core component of the characterization of schizophrenia, a sizable percentage of patients are classified as unimpaired by traditional definitions of impairment. The purpose of this study was to determine the percentage of patients with schizophrenia meeting criteria for a "cognitive function decrement" defined as a current level of cognitive function that falls below the level predicted by premorbid estimates.

Methods: Linear regression analyses were performed on a healthy control population to determine a predicted composite cognitive score based on maternal education, paternal education, and reading score as indicators of premorbid intellectual function.

The Brief Assessment of Cognition in Schizophrenia: reliability, sensitivity, and comparison with a standard neurocognitive battery.

Studies of neurocognitive function in patients with schizophrenia use widely variable assessment techniques. Clinical trials assessing the cognitive enhancing effect of new medications have used neurocognitive assessment batteries that differed in content, length and administration procedures. The Brief Assessment of Cognition in Schizophrenia (BACS) is a newly developed instrument that assesses the aspects of cognition found to be most impaired and most strongly correlated with outcome in patients with schizophrenia.

Source monitoring improvement in patients with schizophrenia receiving antipsychotic medications.

Rationale: The absence of a relationship between cognitive deficit treatment response and positive symptom treatment response is often assumed, and few data have shed light on this issue. Most of these data have been collected using standard neuropsychological measures, which are ill-designed to assess the types of neurocognitive disturbances associated with psychotic symptoms. This study investigates the effect of treatment on source monitoring performance and its relation to the reduction of certain psychotic symptoms associated with the inability to identify self-generated mental events, known as "autonoetic agnosia".