Cognition and community functioning in schizophrenia: The nature of the relationship.

Abstract

Although cognition is one of the most important predictors of community functioning in schizophrenia, little is known about the causes of this correlation. To our knowledge, this study is the first to examine the extent to which this correlation is genetically mediated and whether the genetic correlation is specific to schizophrenia. Six hundred thirty-six participants from 43 multigenerational families with at least two relatives with schizophrenia and 135 unrelated controls underwent diagnostic interview and cognition and functioning assessment. Quantitative genetic analyses were conducted using maximum-likelihood variance decomposition methods implemented in SOLAR (Almasy & Blangero, 1998). Among patients with schizophrenia, cognition and community functioning were positively correlated and genetic effects shared between them were significant contributors to this relationship whereas environmental effects shared between them were not. In contrast, genetic effects were not shared significantly between cognition in depressed or nondiagnosed relatives and community functioning in schizophrenia. In all analyses, the contributions of social cognition to community functioning were accounted for by general cognition. These findings support heritable factors that contribute to the correlation between cognition and community functioning that are relatively specific to schizophrenia and are not significantly shared with depression or a lack of psychopathology. This suggests the possibility of identifying specific genetic variants that contribute to this correlation and to these important individual differences among schizophrenia patients. (PsycINFO Database Record

Why does age of onset predict clinical severity in schizophrenia? A multiplex extended pedigree study

“…Our study also assessed the heritability of community functioning in schizophrenia, which remains an understudied area (for a review of the studies that assess heritabilities of cognition and community functioning in schizophrenia, see Kuo et al, 2018 (although this is standard in most studies). It is also possible that this estimate is affected by study design-heritability estimates in the literature varied widely, and the only other study that used an extended pedigree design found age of onset to be 33% heritable (Hare et al, 2010), which is similar to our estimate (even with a substantially larger sample of 717 individuals).…”

“…Less research has focused on the genetic effects on symptom severity, but one recent metaanalysis of five sibling studies found that negative symptoms (h 2 = 0.34), disorganized symptoms (h 2 = 0.56), and positive symptoms (h 2 = 0.36) were all significantly heritable (p < .0001; Rietkerk et al, 2008), whereas the results from genetic association studies are less consistent (e.g., Xavier & Vorderstrasse, 2017). In a similar vein to symptom severity, the substantial amount of work regarding community functioning in schizophrenia has infrequently focused on the role of genetic effects, although several family studies have found global functioning to be significantly correlated among first-degree relatives, with heritability estimates between 0.50 and 0.68% (e.g., Cardno et al, 1998;Kendler et al, 1997;Kuo et al, 2018;McGrath et al, 2009;Vassos et al, 2008).…”

A 1.5-Year Longitudinal Study of Social Activity in Patients With Schizophrenia

“…Some components of these impairments (e.g., ability to follow rules at school and/or work and cognitive functions) appear relatively stable over time before and/or after the onset of schizophrenia (21–24, 27), while other components (e.g., ability to make and maintain friends, social and cognitive functions), and a subgroup of the patients, showed a progressive decline or improvement with increased illness chronicity (21, 22, 25, 26). Additionally, impairments in premorbid adjustments and cognitive and community functions have been reported in patients with schizophrenia and their unaffected relatives (21, 23, 28–30), suggesting that these impairments may be due to shared genetic and/or environmental risk factors. To date, little is known about the longitudinal effects of cognitive function, daily living skills, social function, psychiatric symptoms, and medications on social activity (h/week) in patients with schizophrenia.…”

Polygenic Risk Scores Shed Light on the Relationship between Schizophrenia and Cognitive Functioning: Review and Meta-Analysis

“…In conclusion, accumulating evidence indicates that genetic risk of schizophrenia may contribute to cognitive dysfunction and reciprocally [22,37]. Other data indicate a strong and specific genetic link between cognitive impairment and loss of functioning [36], yet with few data to date. Recent findings suggest that the genetic risk of schizophrenia may differentially impact cognition in patients versus not, shedding an insight on the underpinning of cognitive impairment related to schizophrenia [28,29].…”

“…In SZ patients, genetics would specifically explain the large association between cognition and community functioning. Indeed, a large study (on 43 families, each with at least two SZ patients and 135 controls), authors found that genetic effects are shared between cognition and functioning in schizophrenia, but not with another psychiatric diagnosis (major depression) or in healthy individuals [36].…”