Long-Term Impacts of Cognitive Impairment in Psychosis

by Matteo Cella, Professor of Clinical Psychology at King's College London and Clinical Psychologist for the South London and Maudsley NHS Foundation Trust

Cognitive impairment is a hallmark feature of psychosis, often emerging early and persisting throughout life, but there is limited research on the long-term outcomes of cognitive deterioration. A recent paper reported on a 25-year longitudinal follow-up study using data from the Suffolk County Mental Health Project (SCMHP). The research focused on evaluating long-term predictors and outcomes of cognitive impairment in people with psychosis.

Four hundred people who were first admitted to hospital experiencing an episode of psychosis between 1989 and 1995 had their cognition assessed at four timepoints: 6 months, 2 years, 20 years, and 25 years post-admission.

A key finding was that cognition declined on average 0.31 IQ points per year. Factors like socioeconomic status, race, cannabis use, and initial diagnosis seemed to influence overall cognitive ability but did not predict the rate of decline. Individuals with better psychosocial functioning before their first admission tended to have higher cognitive scores throughout the study. Although a history of cannabis use was also associated with better cognitive performance, this should not be interpreted as cannabis having a protective effect, as cannabis use has been linked to worse clinical outcomes in people with psychosis.

Individuals who experienced faster cognitive deterioration were significantly less likely to achieve remission or recovery. These people also had lower odds of being employed, financially independent, or living independently 25 years after their first experience of psychosis, and had notably worse social functioning.

These findings suggest that cognitive decline is a key driver of long-term disability and so could be a valuable marker for identifying individuals at risk of poor outcomes and then using this information to tailor interventions much earlier.

Therapies like cognitive remediation, vocational training, and social skills development are not sufficiently used in clinical services, and a wider implementation of these approaches has the potential to limit the long-term functional difficulties often experienced by people with psychosis.

While we still can’t accurately predict who will decline, we now know conclusively that cognitive deterioration is a powerful indicator of future disability. Addressing it head-on is the key to improving quality of life for individuals living with psychosis.

Read the full paper here: Yang et al. (2025). Predictors and Outcomes Associated with 25-Year Cognitive Decline in Psychotic Disorders. Schizophrenia Bulletin.

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