Abstract

Importance: The majority of patients with psychotic disorders experience severe cognitive impairment, but the onset and course of this impairment remains unclear. Moreover, the course of cognitive functions in other psychiatric conditions remains largely unexamined.
Objective: To chart the course of general and specific cognitive functions in individuals with psychotic disorders, psychotic experiences and depression.
Design: The Avon Longitudinal Study of Parents and Children (ALSPAC) is a prospective cohort study comprising all live births between 1991 and 1992 in Avon, United Kingdom.
Setting: General population.
Participants: All participants who underwent cognitive testing at 18 months, 4, 8, 15 and 20 years, and psychiatric assessment at age 18 were included.
Exposures: Individuals with psychotic disorder, psychosis with depression, psychotic experiences, and depression were compared to controls.
Main Outcomes: Full-scale, verbal and non-verbal IQ, at ages 18 months, 4, 8, 15 and 20 years, as well as measures of processing speed, working memory, language, visuospatial ability and attention at ages 8 and 20.
Results: At ages 18 months, 4, 8, 15 and 20 years, a total of 511 (mean (SD) age = 1.53 (0.03), 47.6% male), 483 (mean (SD) age = 4.07 (0.03), 47.1% male), 3930 mean (SD) age = 58 8.65 (0.29), 44.1% male), 3783 (mean (SD) age = 5.45 (0.27), 44.6% male) and 257 (mean 59 (SD) age = 20.06 (0.55), 35.0% male) subjects, respectively, were available for analyses. Individuals with 60 psychotic disorder showed continually increasing deficits between infancy (18 months) and adulthood (20 years) in full-scale IQ (effect size of change (ESΔ) =−1.09,
p=.02), and non-verbal IQ (ESΔ =−0.94, p=.008). The depression group showed a small, increasing deficit in non-verbal IQ (ESΔ =−0.29, p=.04) between infancy and adulthood. Between ages 8 and 20, the psychotic disorder group exhibited developmental lags (i.e. slower growth) in measures of processing speed, working memory and attention (ESΔ =−0.68, p=.001; ESΔ =−0.59, p=.004; ESΔ =−0.44, p=.001), and large, static deficits in measures of language and visuospatial ability (ES=−0.87, p=.005; ES=−0.90, p=.001). There was only weak evidence for cognitive deficits in the psychosis with depression, and psychotic experiences groups.
Conclusions and Relevance: These findings suggest that the origins of psychotic disorder involve dynamic developmental processes, affecting both verbal and non-verbal abilities throughout the first two decades of life and leading to increasing dysfunction. These developmental processes do not manifest in other psychiatric disorders, such as psychosis with depression, and depression.
Original languageEnglish
Pages (from-to)270-279
Number of pages10
JournalJAMA Psychiatry
Volume75
Issue number3
DOIs
Publication statusPublished - 1 Mar 2018

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