The relation between neurocognitive dysfunction and impaired insight in patients with schizophrenia

The present study aimed to (i) evaluate the association between insight and measures of executive functions and working memory in a sample of 132 patients with schizophrenia and (ii) to explore to what proportion neurocognitive dysfunction contributed to the variance in insight after controlling for symptomatology.

Subjects were evaluated with a standardized neurocognitive test battery and a semi-structured interview, the Psychosis Evaluation tool for Common use by Caregivers (PECC). PECC, apart from evaluating symptoms and side-effects, measures insight on a 4-point scale by two of its dimensions: awareness of having a mental illness (AMI) and awareness of having symptoms attributed to a mental illness (ASAMI). Executive functioning was measured by the Wisconsin Card Sort Test (WCST) and the Trail Making B (TMB). Working memory was measured by the Letter Number Sequencing (LNS) test from the Wechsler Adult Intelligence Scale (WAIS).

Only one significant association was found after correction for multiple testing, between WCST categories completed and AMI (r=-0.29, p=0.0006). WCST categories completed explained only 7.9% of the variance in AMI, while symptomatology explained 20% of variance in AMI and 16.5% of variance in ASAMI.

The current results show a significant but subtle association with the WCST, which is in agreement with earlier literature. No other associations between cognitive functioning and insight were found. In general, these findings seem to suggest that factors other than cognition have a greater impact on insight in patients with schizophrenia.