Birth weight may shape functioning after first-episode psychosis through cognitive reserve

Higher birth weight was associated with better functioning one year after a first episode of psychosis, and the link appeared to run through cognitive reserve and verbal memory, according to a longitudinal cohort study published in Nature Mental Health on 28 October 2026.

The study, led by M. Florencia Forte and colleagues, followed 117 patients with nonaffective first-episode psychosis (FEP). A separate group of 162 healthy controls contributed cross-sectional comparisons of birth weight and cognitive reserve. Cognitive deficits are a core feature of FEP and are closely tied to impaired day-to-day functioning, and higher cognitive reserve is considered a protective factor, while early developmental factors such as lower birth weight have been suspected of contributing to poorer cognition.

Birth weight itself did not differ between the patient and control groups. Cognitive reserve, however, was significantly lower in the patients with FEP, with a reported probability value below 0.001.

Using serial mediation models that tested verbal memory and working memory separately, the researchers found that higher birth weight was associated with greater cognitive reserve (β = 4.64, P = 0.014). Greater cognitive reserve was in turn associated with better verbal memory (β = 2.21, P = 0.001), and better verbal memory was associated with better functioning at one year (β = 0.07, P = 0.004).

The direct effect of birth weight on functioning was not statistically significant. According to the authors, this pattern supports a specific indirect pathway in which birth weight relates to later functioning through cognitive reserve and verbal memory, rather than through a direct association.

Because the study is observational, the findings describe statistical associations within this cohort and do not establish that birth weight causally determines outcomes. The control comparison of birth weight and cognitive reserve was cross-sectional, so it cannot speak to change over time.

The results suggest that early developmental measures may relate to long-term outcomes in psychosis through cognitive mechanisms, and that cognitive reserve could be a meaningful marker in longitudinal research on first-episode psychosis. The authors note that the study examined whether birth weight was associated with one-year functioning through cognitive reserve and cognition in patients with nonaffective FEP.

Subject of Research: The association between birth weight, cognitive reserve and one-year functioning in first-episode psychosis

Article Title: Birth weight, cognitive reserve and outcomes after first-episode psychosis

Article References: Forte, M. F., Fontàs, A. H., Garriga, M., Mezquida, G., García-Rizo, C., Vieta, E., Pina-Camacho, L., Merchán-Naranjo, J., Cuesta, M. J., Berge, D., Baeza, I., Stainton, A., Martínez-Arán, A., Amoretti, S., PEPs group, Perez-Ramos, A., Guasch-Capella, N., Cavone, V., Abregú-Crespo, R., … Balanzá, V. (2026). Birth weight, cognitive reserve and outcomes after first-episode psychosis. Nature Mental Health. https://doi.org/10.1038/s44220-026-00751-0

Image Credits: AI Generated

DOI: 10.1038/s44220-026-00751-0

Keywords: first-episode psychosis, birth weight, cognitive reserve, verbal memory, working memory, longitudinal cohort study, functioning, cognition, Nature Mental Health, serial mediation, Birth, weight