[Subjective cognition in schizophrenia]

Given the extent, magnitude and functional significance of the neurocognitive deficits of schizophrenia, growing attention has been paid recently to patients' self-awareness of their own deficits. Thus far, the literature has shown either that patients fail to recognize their cognitive deficits or that the association between subjective and objective cognition is weak in schizophrenia. The reasons for this lack of consistency remain unexplained but may have to do, among others, with the influence of potential confounding clinical variables and the choice of the scale used to measure self-awareness of cognitive deficits. In the current study, we sought to examine the relationships between subjective and objective cognitive performance in schizophrenia, while controlling for the influence of sociodemographic and psychiatric variables.

Eighty-two patients with a schizophrenia-spectrum disorder (DSM-IV criteria) were recruited. Patients' subjective cognitive complaints were evaluated with the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS), the most frequently used scale to measure self-awareness of cognitive deficits in schizophrenia. Neurocognition was evaluated with working memory, planning and visual learning tasks taken from Cambridge Neuropsychological Tests Automated Battery. The Stroop Color-Word test was also administered. Psychiatric symptoms were evaluated with the Positive and Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia. The relationships between subjective and objective cognition were evaluated with multivariate hierarchic linear regression analyses, taking into consideration potential confounders such as sociodemographic and psychiatric variables. Finally, a factor analysis of the SSTICS was performed.

For the SSTICS total score, the regression analysis produced a model including two predictors, namely visual learning and Stoop interference performance, explaining a moderate portion of the variance. Visual learning performance was the most consistent predictor of most SSTICS subscores (e.g. episodic memory, attention, executive functioning, language and praxis). Modest associations were found between the PANSS cognitive factor and objective cognition (e.g. Stroop interference, visual learning, and working memory). Finally, the factor analysis revealed a 6-factor solution that echoes the classification of the items of the SSTICS based on the neuropsychological literature.

Using a scale having good internal validity, as shown by the factor analysis, the current study highlighted modest associations between subjective and objective cognitive performance, which suggests that schizophrenia patients are only partially aware of their own cognitive deficits. The results also showed a lack of correspondence between the impaired cognitive domain and the domain of cognitive awareness. It should be noted that clinicians were not better than patients at evaluating their cognitive deficits. Future research will need to determine if the observations reported here are schizophrenia-specific or not.