Cognitive Control in Patients With Mental Illness Differs by Diagnosis

Patients with schizophrenia, schizoaffective disorder, and bipolar disorder also have significant impairments in cognitive and attentional control, according to study data published in Schizophrenia Research.  

Participants were recruited from sites involved in the Cognitive Neuroscience Test Reliability and Clinical applications for Schizophrenia Consortium. The present study cohort comprised patients age 18 to 56 years with schizophrenia (n=90), schizoaffective disorder (n=83), bipolar disorder type I with a history of psychotic features (n=58), and healthy controls (n=72). Clinical assessments were performed with the Young Mania Rating Scale (YMRS) and the 24-item Brief Psychiatric Rating Scale (BPRS). Everyday functioning was captured with the University of California San Diego Performance Skills Assessment-B (UPSA-B). A Dot-Probe Expectancy version of the AX-Continuous Performance Task was used to assess d-prime context and lapsing rate. In this test, subjects were asked to respond by button press to a target probe (A) when it followed a target cue (X), but not otherwise. That is, response to an AX trial was correct, while response to AY, BX, or BY trials were incorrect. D-prime context was calculated as a function of AX hits minus BX false alarms and was used as an index of cognitive control. Attentional control was also captured through “lapsing” rate, or the percentage of missed AX or BY trials.

The final analytic sample comprised 84 patients with schizophrenia, 77 patients with schizoaffective disorder, 58 patients with bipolar disorder, and 72 controls, following exclusion of patients who did not meet AX performance criteria (>56% incorrect AX or 50% incorrect BY trials). Patient diagnostic groups did not differ by age, although gender and site distribution varied. Patient groups differed significantly in YMRS (P =.003), BPRS (P <.001), and UPSA-B (P <.001) scores. A significant main effect of group on d-prime context was observed, driven by deficits in patients with schizophrenia (P <.001), schizoaffective disorder (P <.001), and bipolar disorder (P =.025) compared with controls. A group by gender interaction was also observed, driven by deficits in d-prime context in women with schizophrenia (P =.009) and in men with bipolar disorder (P =.023).

A significant main effect of diagnosis was also observed for lapsing rate (P <.001), driven by significant deficits in patients with schizophrenia (P <.001) and schizoaffective disorder (P =.016) relative to controls. Patients with bipolar disorder displayed significantly less lapsing than patients with schizophrenia (P =.007). Across all participants, a significantly negative correlation was observed between d-prime context and lapsing rate (P <.001), a trend that was replicated within each patient group. A negative association was observed between d-prime context and total YMRS (P =.002) and BPRS (P =.005) scores, as well as between lapsing rate and BPRS disorganization (P =.001) and mania (P =.023) subscale scores. A positive association was observed between d-prime context and total UPSA-B score (P <.001), while lapsing rate was negatively associated with total UPSA-B score (P <.001).

These data describe a “continuum of dysfunction in cognitive control” across psychiatric diagnoses. Further research is necessary to explore the deficits in cognitive control experienced in each disorder.

Reference

Smucny J, Barch DM, Gold JM, et al. Cross-diagnostic analysis of cognitive control in mental illness: Insights from the CNTRACS consortium [published online January 28, 2019]. Schizophr Res. doi: 10.1016/j.schres.2019.01.018