Self-perceived cognitive functioning and its relationship with objective performance in first-episode schizophrenia: the Subjective Cognitive Impairment Scale.

BACKGROUND

Self-perceived cognitive dysfunction is under-recognized in clinical practice and under-studied in schizophrenia, particularly in the early illness stage. Findings on the relationship between subjective and objective cognitive measures were inconsistent. This study aimed to examine psychometric properties of a newly developed scale, Subjective Cognitive Impairment Scale (SCIS) and to investigate the relationship of self-reported ratings with objective test performance in first-episode schizophrenia.

METHODS

One hundred one Chinese patients aged 18 to 64years presenting with first episode schizophrenia-spectrum disorder were studied. A comprehensive set of assessments examining objective cognitive functioning, clinical and treatment characteristic were administered. Internal consistency, factor structure and construct validity of SCIS were evaluated. Correlations of scale score with objective cognitive measures, clinical and treatment variables were examined.

RESULTS

A single-factor underlying the structure of SCIS items was demonstrated by principal components analysis. Cronbach's alpha coefficient for the scale was 0.92. SCIS score was positively correlated with depression and anxiety symptom severity, and duration of untreated psychosis. SCIS score was not associated with other symptom dimensions, insight and chlorpromazine equivalents. No significant correlations were observed between SCIS score and objective cognitive measures with the exception of letter-number span test.

CONCLUSION

Our results provided preliminary evidence in support of reliability and validity of SCIS in evaluating patient's cognitive complaints. A lack of correspondence between subjective and objective cognitive functioning suggested that they may represent two distinct constructs with potentially differential therapeutic implications. Further research is warranted to examine ecological validity and clinical utility of the scale.