AbstractBackgroundThe neurodevelopmental model of psychosis was established over 30 years ago; however, the developmental influence on psychotic symptom expression – how age affects clinical presentation in first-episode psychosis – has not been thoroughly investigated.MethodsUsing generalized additive modeling, which allows for linear and non-linear functional forms of age-related change, we leveraged symptom data from a large sample of antipsychotic-naïve individuals with first-episode psychosis (N= 340, 12–40 years, 1–12 visits), collected at the University of Pittsburgh from 1990 to 2017. We examined relationships between age and severity of perceptual and non-perceptual positive symptoms and negative symptoms. We tested for age-associated effects onchangein positive or negative symptom severity following baseline assessment and explored the time-varying relationship between perceptual and non-perceptual positive symptoms across adolescent development.ResultsPerceptual positive symptom severity significantly decreased with increasing age (F= 7.0,p= 0.0007;q= 0.003) while non-perceptual positive symptom severity increased with age (F= 4.1,p= 0.01,q= 0.02). Anhedonia severity increased with increasing age (F= 6.7,p= 0.00035;q= 0.0003), while flat affect decreased in severity with increased age (F= 9.8,p= 0.002;q= 0.006). Findings remained significant when parental SES, IQ, and illness duration were included as covariates. There were no developmental effects on change in positive or negative symptom severity (allp> 0.25). Beginning at age 18, there was a statistically significant association between severity of non-perceptual and perceptual symptoms. This relationship increased in strength throughout adulthood.ConclusionsThese findings suggest that as maturation proceeds, perceptual symptoms attenuate while non-perceptual symptoms are enhanced. Findings underscore how pathological brain–behavior relationships vary as a function of development.