Neurocognition, insight into illness and subjective quality-of-life in schizophrenia: what is their relationship?

Subjective quality-of-life (SQOL) has been recognized as a crucial domain of outcome in schizophrenia treatment, and yet its determinants are not well understood. In a recent meta-analytic investigation of 10 studies of neurocognition and SQOL in schizophrenia (Tolman and Kurtz, Scz Bull, 2010) measures of crystallized verbal ability and processing speed were moderately negatively correlated with SQOL. One potential explanation for inverse relationships between measures of elementary neurocognition and SQOL is that higher levels of cognition may serve as a proxy for better insight into the illness, and better consequent recognition of illness-related functional impairment. This study sought to determine whether: (1) symptoms, neurocognitive variables, and insight into illness influence SQOL; and, (2) whether insight mediated or moderated a relationship between elementary neurocognitive function and SQOL. Seventy-one stabilized clients with schizophrenia or schizoaffective disorder were administered a neuropsychological test battery, symptom and subjective quality-of-life measures. Elementary neuropsychological measures of crystallized verbal ability, attention and working memory, and problem-solving were all inversely related to SQOL. Insight into illness and depression severity, but not positive and negative symptoms, was also inversely related to SQOL. Insight was not found to mediate or moderate any of the relationships between elementary neurocognition and SQOL. Taken together, these findings suggest that neurocognition and insight into illness have inverse relationships to SQOL and that elementary neurocognition does not influence SQOL through its link with illness insight.