The Course of General Cognitive Ability in Individuals With Psychotic Disorders.

Importance: Schizophrenia is associated with major cognitive deficits and has been conceptualized as both a neurodevelopmental and a neurodegenerative disorder. However, when deficits develop and how they change over the course of illness is uncertain. Objective: To trace cognition from elementary school to old age to test neurodevelopmental and neurodegenerative theories of psychotic disorders. Design, Setting, and Participants: Data were taken from the Suffolk County Mental Health Project, a first-admission longitudinal cohort study of individuals with psychotic disorders. Participants were recruited from all 12 inpatient psychiatric facilities in Suffolk County, New York. This analysis concerns the 428 participants with at least 2 estimates of general cognitive ability. Data were collected between September 1989 and October 2019, and data were analyzed from January 2020 to October 2021. Exposures: Psychiatric hospitalization for psychosis. Main Outcomes and Measures: Preadmission cognitive scores were extracted from school and medical records. Postonset cognitive scores were based on neuropsychological testing at 6-month, 24-month, 20-year, and 25-year follow-ups. Results: Of the 428 included individuals (212 with schizophrenia and 216 with other psychotic disorders), 254 (59.6%) were male, and the mean (SD) age at psychosis onset was 27 (9) years. Three phases of cognitive change were observed: normative, declining, and deteriorating. In the first phase, cognition was stable. Fourteen years before psychosis onset, those with schizophrenia began to experience cognitive decline at a rate of 0.35 intelligence quotient (IQ) points per year (95% CI, 0.29-0.42; P < .001), a significantly faster decline than those with other psychotic disorders (0.15 IQ points per year; 95% CI, 0.08-0.22, P < .001). At 22 years after onset, both groups declined at a rate of 0.59 IQ points per year (95% CI, 0.25-0.94; P < .001). Conclusions and Relevance: In this cohort study, cognitive trajectories in schizophrenia were consistent with both a neurodevelopmental and neurodegenerative pattern, resulting in a loss of 16 IQ points over the period of observation. Cognitive decline began long prior to psychosis onset, suggesting the window for primary prevention is earlier than previously thought. A window for secondary prevention emerges in the third decade of illness, when cognitive declines accelerate in individuals with schizophrenia and other psychotic disorders.

The 20-Year Longitudinal Trajectories of Social Functioning in Individuals With Psychotic Disorders.

OBJECTIVE: Social impairment is a long-recognized core feature of schizophrenia and is common in other psychotic disorders. Still, to date the long-term trajectories of social impairment in psychotic disorders have rarely been studied systematically. METHODS: Data came from the Suffolk County Mental Health Project, a 20-year prospective study of first-admission patients with psychotic disorders. A never-psychotic comparison group was also assessed. Latent class growth analysis was applied to longitudinal data on social functioning from 485 respondents with schizophrenia spectrum disorders and psychotic mood disorders, and associations of the empirically derived trajectories with premorbid social adjustment, diagnosis, and 20-year outcomes were examined. RESULTS: Four mostly stable trajectories of preserved (N=82; 59th percentile of comparison group sample distribution), moderately impaired (N=148; 17th percentile), severely impaired (N=181; 3rd percentile), and profoundly impaired (N=74; 1st percentile) functioning best described the 20-year course of social functioning across diagnoses. The outcome in the group with preserved functioning did not differ from that of never-psychotic individuals at 20 years, but the other groups functioned significantly worse. Differences among trajectories were already evident in childhood. The two most impaired trajectories started to diverge in early adolescence. Poorer social functioning trajectories were strongly associated with other real-world outcomes at 20 years. Multiple trajectories were represented within each disorder. However, more participants with schizophrenia spectrum disorders had impaired trajectories, and more with mood disorders had better functioning trajectories. CONCLUSIONS: The results highlight substantial variability of social outcomes within diagnoses-albeit overall worse social outcomes in schizophrenia spectrum disorders-and show remarkably stable long-term impairments in social functioning after illness onset across all diagnoses.

Validity and stability of performance-based estimates of premorbid educational functioning in older patients with schizophrenia.

This paper presents the results of two studies of the validity of word-recognition reading as an indicator of premorbid functioning in schizophrenia. The first examined the stability over a 6-year follow-up period of word recognition reading compared to other aspects of cognitive functioning, including verbal learning and delayed recall, verbal fluency, constructional skills, and naming ability. The second study examined the relative predictive power of indicators of premorbid functioning as compared to current cognitive functioning for the prediction of current social and self-care skills. In the first study 218 patients with chronic schizophrenia participated. For the second study, 231 male veterans with schizophrenia were assessed for cognitive functioning, indicators of premorbid adjustment, and current functional status. Analyses of the differences between correlations indicated that word recognition reading ability was significantly more stable than other aspects of cognitive functioning over a six-year period during which decline in some other aspects of performance was found. In the second study, premorbid educational and social attainment, word recognition reading skill, and current cognitive functioning were all significantly related to current functional status, defined by correlations with ratings of current functional status. Path analyses indicated, however, that current cognitive functioning was the only significant predictor of current functional status when the intercorrelations of the variables were considered. In sum, Premorbid functioning estimated with word-recognition reading was stable over time (study 1) and correlated with both current cognitive and functional status (study 2). The results of these two studies suggest that word-recognition reading skills are useful screening instruments to estimate premorbid functioning even in deteriorated patients with schizophrenia.

Working memory performance in poor outcome schizophrenia: relationship to age and executive functioning.

Performance on the Letter-Number Sequencing (LNS) and Wisconsin Card Sorting Tests (WCST) have been shown to be significantly correlated in patients with schizophrenia, a relationship postulated to be due to working memory demands of the two tests (Gold, Carpenter, Randolph, Goldberg, & Weinberger, 1997). An alternative explanation for the association between these two tests is their sorting demands, in that both require sorting of information albeit in slightly different ways. If the latter explanation is valid, then working memory tasks that do not require sorting or other conceptualization demands should be less predictive of WCST performance than LNS. These hypotheses were examined in 34 poor outcome patients with schizophrenia, one-half of whom were over the age of 65. Patients were evaluated on Digit Span Forward, spatial working memory, LNS, and the WCST. It was found that WCST performance was significantly associated with performance on the LNS but no other working memory task. Age related performance differences were greatest on the WCST Categories and floor effects were noted on this test in one-half of the subjects. Analyses predicting WCST Categories in subjects whose scores were greater than zero (n = 16) also demonstrated that LNS, but not Digit Span or spatial working memory (any delay) predicted WCST performance. These findings indicate that LNS may be an index of executive functioning, particularly in patients who cannot perform the WCST.