Abstract
Among adults with schizophrenia, evidence suggests that premorbid deficits in different cognitive domains follow distinct developmental courses during childhood and adolescence. The aim of this study was to delineate trajectories of adolescent cognitive functions prospectively among different groups of youth at-risk for schizophrenia, relative to their typically developing (TD) peers. Using linear mixed models adjusted for sex, ethnicity, parental occupation and practice effects, cognitive development between ages 9 and 16years was compared for youth characterised by a triad of well-replicated developmental antecedents of schizophrenia (ASz; N=32) and youth with a least one affected relative with schizophrenia or schizoaffective disorder (FHx; N=29), relative to TD youth (N=45). Participants completed measures of IQ, scholastic achievement, memory and executive function at three time-points, separated by approximately 24-month intervals. Compared to TD youth, both ASz and FHx youth displayed stable developmental deficits in verbal working memory and inhibition/switching executive functions. ASz youth additionally presented with stable deficits in measures of vocabulary (IQ), word reading, numerical operations, and category fluency executive function, and a slower rate of growth (developmental lag) on spelling from 9 to 16years than TD peers. Conversely, faster rates of growth relative to TD peers (developmental delay) were observed on visual and verbal memory, and on category fluency executive function (ASz youth only) and on matrix reasoning (IQ) and word reading (FHx youth only). These differential patterns of deviation from normative adolescent cognitive development among at-risk youth imply potential for cognitive rehabilitation targeting of specific cognitive deficits at different developmental phases.
Highlights
Schizophrenia is preceded by childhood dysfunctions in multiple cognitive domains (Dickson, Laurens, Cullen, & Hodgins, 2012), but such dysfunction may follow different developmental trajectories
This study aimed to extend prior research by mapping developmental trajectories of cognitive functioning from childhood to adolescence (9– 16 years) in youth at high-risk for schizophrenia relative to typically developing youth, across a range of cognitive functions known to be affected in schizophrenia
Relative to the typically developing (TD) group, antecedents of schizophrenia (ASz) individuals displayed a stable deficit on IQ-vocabulary, SA-word reading, SA-numerical operations, and EF-inhibition/switching; and the FHx group displayed a stable deficit on EF-Inhibition
Summary
Schizophrenia is preceded by childhood dysfunctions in multiple cognitive domains (Dickson, Laurens, Cullen, & Hodgins, 2012), but such dysfunction may follow different developmental trajectories. Among children who develop schizophrenia in adulthood compared to those who do not, prior research has distinguished a premorbid trajectory of developmental deficit from age 4 to 15 years on measures of general intelligence (IQ), scholastic achievement, and verbal abilities, in which premorbid cognitive impairments emerge early and remain stable (Cannon et al, 2000; Crow, Done, & Sacker, 1995; Jones, Rodgers, Murray, & Marmot, 1994; Reichenberg et al, 2010). ASz youth presented with stable deficits in measures of vocabulary (IQ), word reading, numerical operations, and category fluency executive function, and a slower rate of growth (developmental lag) on spelling from 9 to 16 years than TD peers. Faster rates of growth relative to TD peers (developmental delay) were observed on visual and verbal memory, and on category fluency executive function (ASz youth only) and on matrix reasoning (IQ) and word reading (FHx youth only).
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