Cannabis use in first-episode psychosis overwhelmed the protective effects of cognitive reserve on functioning

What the researchers found

Cognitive reserve was associated with better cognitive performance regardless of cannabis use. However, its protective effects on clinical and functional outcomes were seen only in non-cannabis users. Cannabis use appeared to override the protective effect of cognitive reserve on functioning at 2-year follow-up.

Why it matters

Cognitive reserve is typically protective in brain disorders, but cannabis use appears to negate this protection in psychosis, suggesting cannabis effects on functional outcomes may be particularly difficult to buffer against.

The numbers in context

CR predicted better outcomes only in non-cannabis users for both affective and non-affective psychosis. CR mediated cognition-functioning relationship only in non-users. Follow-up: 2 years.

How the study worked

Longitudinal study of first-episode psychosis patients (affective and non-affective) comparing cannabis users vs. non-users. Linear regression assessed cognitive reserve as predictor at baseline and 2-year follow-up. Mediation analyses explored cognitive reserve mediating the cognition-functioning relationship.

What this study cannot tell us

Small affective psychosis subgroup. Cannot determine if cannabis degrades cognitive reserve or blocks its expression. Cannabis use patterns (frequency, potency) not detailed.

How to read the evidence

Longitudinal design with 2-year follow-up and appropriate mediation analyses, though subgroup sizes are limited.

When this study was published

Published in 2022.

The bigger picture

This finding has implications for prognosis: even high-functioning individuals with good cognitive reserve may not be protected from the functional impact of cannabis use during psychosis.

Questions still open

• If patients stop cannabis use, does cognitive reserve regain its protective role? What mechanisms allow cannabis to override cognitive reserve?

Common questions

Read the original research

Is the effect of cognitive reserve in longitudinal outcomes in first-episode psychoses dependent on the use of cannabis?

Journal of affective disorders, 302, 83-93

Citation

Amoretti, Silvia; Verdolini, Norma; Varo, Cristina; Mezquida, Gisela; Sánchez-Torres, Ana M; Vieta, Eduard; Garcia-Rizo, Clemente; Lobo, Antonio; González-Pinto, Ana; Abregú-Crespo, Renzo; Corripio, Iluminada; Serra, Maria; de la Serna, Elena; Mané, Anna; Ramos-Quiroga, J Antoni; Ribases, Marta; Cuesta, Manuel J; Bernardo, Miguel. (2022). Is the effect of cognitive reserve in longitudinal outcomes in first-episode psychoses dependent on the use of cannabis?. Journal of affective disorders, 302, 83-93. https://doi.org/10.1016/j.jad.2022.01.077

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