Lack of insight may play a central role in mediating the relationship between cognitive impairment awareness and schizophrenia symptoms, according to research published in the European Archives of Psychiatry and Clinical Neuroscience.
Researchers set out to correlate symptom severity in schizophrenia with self-appraisals of cognitive defects (SACD) and to explore the mediational role of insight between symptom severity and SACD. The investigators assessed 109 consecutive patients hospitalized for an index schizophrenia episode using the Positive and Negative Syndrome Scale (PANSS) and the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS) measure.
Participants included 70 men and 39 women, all of whom were being treated with an antipsychotic medication with a mean chlorpromazine equivalent dose of 500 mg. The results of a preliminary regression analysis identified the prerequisite relationships for mediation between negative and depressed Wallwork’s factors PANSS and SSTICS total scores (0.34 and 1.27, respectively).
In Model A, the investigators found that the direct effect of a negative PANSS score on the total SSTICS score increased from 0.33 to 0.52 (standardized coefficient 0.308 to 0.199). The standardized indirect effects of a negative PANSS score on SACD through lack of insight was -0.110 (Boot SE 0.044; 95% CI, -0.212 to -0.039). The indirect effect to total effect ratio was -0.55, indicating that lack of insight suppressed the relationship between negative symptoms and self-perceived cognitive deficits.
In Model B, the investigators found that the direct effect of a depressed PANSS score on the total SSTICS score decreased from 1.269 to 0.784 (standardized coefficient 0.224-0.139). Through lack of insight, the standardized indirect effect was 0.086 (Boot SE 0.039; 95% CI, 0.025-0.185).
In Model C, the direct effect of the total SSTICS score on PANSS depressed scores decreased from 0.04 to 0.025 (standardized coefficient 0.22-0.14). The indirect effect to total effect ratio was 0.37.
Study limitations included the cross-sectional nature of the research, which was performed in a “naturalistic clinical setting,” as well as the potential use of a different PANSS factor scoring system. Further studies should include “more detailed instruments to assess insight, its underlying factors, and their mutual relation to subjective cognitive deficit,” the researchers noted.
“The mediation model proposed could contribute to clarify the role of [lack of insight] in the relationship between awareness of cognitive impairment and symptoms in schizophrenia,” the researchers concluded. “The overlap of these constructs is, however, to be further explored.”
Santarelli V, Marucci C, Collazzoni A, et al. Could the severity of symptoms of schizophrenia affect ability of self-appraisal of cognitive deficits in patients with schizophrenia? Lack of insight as a mediator between the two domains [published online November 13, 2019]. Eur Arch Psychiatry Clin Neurosci. doi:10/1007/s00406-019-01082-1