Cannabis ex-users with first-episode psychosis recovered attention closest to healthy levels over 3 years | Research

The takeaway

Among 461 first-episode psychosis patients followed for 3 years, those who quit cannabis showed the most attention improvement, reaching scores closest to healthy controls.

People with psychotic disorders who use cannabis, clinicians encouraging cessation, and researchers studying cognitive recovery in psychosis.

Ex-users achieved attention scores closest to healthy controls at 3 years

What the researchers found

Over 3 years, attention improved most in FEP patients who never used cannabis (n=238), followed by ex-users (n=105) and persistent users (n=43). At follow-up, ex-users achieved attention scores closest to those of healthy controls.

Why it matters

This is one of the largest and longest studies to show that quitting cannabis after a first psychotic episode is associated with meaningful cognitive recovery, with former users ultimately performing near the level of healthy individuals.

The numbers in context

648 total participants (461 patients, 187 controls). 35.3% were cannabis users (187 patients, 42 controls). At 3 years: never-users improved most, ex-users (n=105) reached scores closest to healthy controls, persistent users (n=43) improved least.

How the study worked

Longitudinal study of 461 FEP patients and 187 healthy controls. Cannabis use status categorized as never-user, ex-user, or persistent user. Neuropsychological attention tests administered at baseline and 3-year follow-up.

What this study cannot tell us

Observational design, so unmeasured factors may explain differences between groups. Cannabis use was categorized broadly without detailed frequency or potency data. Attrition over 3 years may introduce selection bias.

How to read the evidence

Strong: large sample (648 participants), 3-year longitudinal design, healthy control group, standardized neuropsychological assessment.

When this study was published

Published in 2022.

The bigger picture

The finding that ex-users outperformed never-users in reaching healthy control levels at 3 years suggests that cognitive recovery after quitting cannabis may be particularly robust in this population.

Questions still open

Why did ex-users reach scores closer to healthy controls than never-users? Could it reflect a pre-existing cognitive advantage in those who used cannabis? Does the timing of quitting relative to the psychotic episode matter?

Common questions

How much did attention improve over 3 years?

All patient groups showed significant improvement, but never-users improved most, followed by ex-users, then persistent users. Patients still performed below healthy controls at all time points.

Did quitting cannabis fully restore attention?

Ex-users came closest to healthy control levels at 3 years, suggesting substantial but not necessarily complete recovery.

Were there attention differences at baseline?

Yes, all patient groups performed worse than controls at baseline, with cannabis users and non-users starting at similar levels.

Read the original research

Longitudinal effects of cannabis use on attentional processes in patients with first episode of psychosis.

Schizophrenia research, 244, 71-80

View on PubMed ↗Publisher’s paper ↗

Citation

Setién-Suero, Esther; Ayesa-Arriola, Rosa; Peña, Javier; Crespo-Facorro, Benedicto; Ojeda, Natalia. (2022). Longitudinal effects of cannabis use on attentional processes in patients with first episode of psychosis.. Schizophrenia research, 244, 71-80. https://doi.org/10.1016/j.schres.2022.05.011