Refining the latent structure of neuropsychological performance in schizophrenia

Objective Schizophrenia patients exhibit impaired working and episodic memory, but this may represent generalized impairment across memory modalities or performance deficits restricted to particular memory systems in subgroups of patients. Furthermore, it is unclear whether deficits are unique from those associated with other disorders. Method Healthy controls (n=1101) and patients with schizophrenia (n=58), bipolar disorder (n=49) and attention-deficit-hyperactivity-disorder (n=46) performed 18 tasks addressing primarily verbal and spatial episodic and working memory. Effect sizes for group contrasts were compared across tasks and the consistency of subjects’ distributional positions across memory domains was measured. Results Schizophrenia patients performed poorly relative to the other groups on every test. While low to moderate correlation was found between memory domains (r=.320), supporting modularity of these systems, there was limited agreement between measures regarding each individual’s task performance (ICC=.292) and in identifying those individuals falling into the lowest quintile (kappa=0.259). A general ability factor accounted for nearly all of the group differences in performance and agreement across measures in classifying low performers. Conclusions Pathophysiological processes involved in schizophrenia appear to act primarily on general abilities required in all tasks rather than on specific abilities within different memory domains and modalities. These effects represent a general shift in the overall distribution of general ability (i.e., each case functioning at a lower level than they would have if not for the illness), rather than presence of a generally low-performing subgroup of patients. There is little evidence that memory impairments in schizophrenia are shared with bipolar disorder and ADHD.

Section: Introductionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Memory systems in schizophrenia: Modularity is preserved but deficits are generalized

Haut

Karlsgodt

Bilder

et al. 2015

“…In step two, a confirmatory factor analysis (CFA) was performed using the remaining half of each group to validate the derived model. As a secondary aim given the limited number of tests in the BACS battery, we also compared the single factor solution determined with the EFA to a model with more factors based on reports from some previous investigations about the cognitive structure of psychotic disorders (Lam et al, 2014; Keefe et al, 2004; McCleery et al, 2015). Model fit was evaluated using the following measures: Tucker-Lewis Index (TLI) (Bollen, 1989), Comparative Fit Index (CFI) (Bentler, 1990), Root Mean Square Approximation (RMSEA) (Browne & Cudeck, 1993), Akaike information criterion (AIC), Bayesian information criterion (BIC), and a Chi-square test of goodness of fit.…”

Section: Methodsmentioning

confidence: 99%

Unitary construct of generalized cognitive ability underlying BACS performance across psychotic disorders and in their first-degree relatives

Hochberger

Hill

Nelson

et al. 2016

Despite robust evidence of neurocognitive dysfunction in psychotic patients, the degree of similarity in cognitive architecture across psychotic disorders and among their respective first-degree relatives is not well delineated. The present study examined the latent factor structure of the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychological battery. Analyses were conducted on 783 psychosis spectrum probands (schizophrenia, schizoaffective, psychotic bipolar), 887 of their first-degree relatives, and 396 non-psychiatric controls from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium. Exploratory factor analysis of BACS subtest scores indicated a single-factor solution that was similar across all groups and provided the best overall data fit in confirmatory analyses. Correlations between the standard BACS composite score and the sum of subscale scores weighted by their loadings on this unitary factor was very high in all groups (r ≥.99). Thus, the BACS assesses a similar unitary cognitive construct in probands with different psychotic disorders, in their first-degree relatives, and in healthy controls, and this factor is well measured by the test’s standard composite score.

“…Neuropsychological impairment is a core feature of schizophrenia (Hill et al, 2004b; Keefe et al, 2007; Lam et al, 2014). Impairments have been reported in many cognitive domains, including verbal learning and memory, verbal fluency, working memory, processing speed, and executive function (Bilder et al, 2002; Hill et al, 2013, 2004a; Saykin et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Cognitive burden of anticholinergic medications in psychotic disorders

Eum

Hill

Rubin

et al. 2017

Background Patients with psychotic disorders are often treated with numerous medications, many of which have anticholinergic activity. We assessed cognition in relation to the cumulative anticholinergic burden of multiple drugs included in treatment regimens of participants from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) study. Method Clinically stable participants with schizophrenia (n=206), schizoaffective disorder (n=131), and psychotic bipolar disorder (n=146) were examined. Anticholinergic properties of all scheduled drugs were quantified using the Anticholinergic Drug Scale (ADS). ADS scores were summed across individual drugs to create a total ADS burden score for each participant and examined in relation to the Brief Assessment of Cognition in Schizophrenia (BACS). Results Anticholinergic burden aggregated across all medications was inversely related to cognitive performance starting at ADS scores of 4 in participants with schizophrenia. Those with ADS scores ≥4 had lower composite BACS scores compared to those with ADS<4 (p=0.004). Among BACS subtests, Verbal Memory was the most adversely affected by high anticholinergic burden. Despite similar anticholinergic burden scores across groups, a significant effect of anticholinergic burden was not detected in schizoaffective or psychotic bipolar disorder. Conclusion We identified an adverse effect threshold of anticholinergic burden on cognition in clinically stable participants with schizophrenia. This relationship was not identified in affective psychoses. Examination of other medications, doses, and clinical measures did not account for these findings. Patients with schizophrenia may have increased cognitive susceptibility to anticholinergic medications and the aggregate effects of one’s medication regimen may be important to consider in clinical practice.