Age-Associated Cognitive Deviations in Early-Onset Psychosis Patients and Their Siblings.

OBJECTIVE: The objective of this study was to test for cognitive impairments and cross-sectional age-associated cognitive deviations in a large, diagnostically diverse, cross-sectional sample of children and adolescents with early-onset psychosis (EOP), their siblings, and nonpsychotic psychiatric control participants. METHODS: EOP probands (N=1,004), their siblings (N=146), and control subjects (N=1,077) were recruited into the Early Psychosis Investigation in Mexico (EPIMex) study. Most EOP probands (84%) had a nonpsychotic psychiatric comorbidity. Most siblings (64%) and control subjects (77%) had a nonpsychotic psychiatric disorder. EOP participants were divided into an affective EOP group (schizoaffective, psychotic depression/bipolar disorders, N=695) and a nonaffective EOP group (schizophrenia, other psychoses, N=309). Seven cognitive functions were measured, and g (general cognitive ability) was derived. The authors tested for cognitive impairments and cross-sectional age-associated cognitive deviations (age-by-group interactions) in nonaffective EOP probands, affective EOP probands, and their siblings, compared to the control group. RESULTS: Nonaffective EOP probands showed impairments across all measures (β=0.27-0.51). Affective EOP probands showed impairments across most measures (β=0.13-0.25). Siblings showed no impairments. Nonaffective EOP participants, affective EOP participants, and siblings showed statistically significant cross-sectional age-associated cognitive deviations on g. Among nonaffective EOP participants, children, adolescents, and adults showed impairments of small, medium, and large magnitude, respectively. Among affective EOP participants, children showed no impairment, adolescents showed small impairments, and adults showed large impairments. Among siblings, children and adolescents showed no impairment, and adults showed large impairments. Nonaffective EOP participants also showed significant age-associated deviations in verbal memory and working memory. Affective EOP participants showed significant age-associated deviations in working memory and verbal fluency. Siblings showed significant age-associated deviations in processing speed. CONCLUSIONS: EOP probands and their siblings showed cross-sectional age-associated cognitive deviations at different ages, and in different functions. Early interventions targeting specific functions during specific developmental periods may prevent further cognitive deviation and impairment. However, longitudinal data are needed to confirm whether the cross-sectional findings reflect within-individual developmental deviation.