Among 543 individuals at clinical high risk for psychosis, those who later converted had significantly slower startle response latency, and cannabis use was associated with increased sensory gating (PPI) in at-risk individuals but not in healthy controls.
Psychiatrists, psychosis researchers, neuroscientists studying sensory processing
58 of 543 clinical high-risk participants converted to psychosis within one year
What the researchers found
CHR participants who converted to psychosis had significantly slower startle latency than non-converters, driven by female participants. PPI showed a significant group-by-cannabis interaction: cannabis users in the CHR group had greater PPI than non-users, opposite to the pattern in healthy controls. PPI correlated significantly with age in CHR but not healthy participants.
Why it matters
Identifying biomarkers that predict who among at-risk individuals will develop psychosis could enable earlier intervention. The finding that cannabis alters sensory gating differently in this population suggests distinct neurobiological effects.
The numbers in context
543 CHR participants, 218 healthy controls, ages 12-35. 58 CHR participants converted to psychosis at 1-year follow-up. Significant group-by-cannabis interaction on PPI. Slower startle latency predicted conversion, driven by females.
How the study worked
Prospective study of 543 CHR and 218 normal comparison participants aged 12-35 from the NAPLS consortium. Startle reactivity, latency, and prepulse inhibition were measured at baseline, with psychotic conversion assessed at 1-year follow-up.
What this study cannot tell us
Observational design; cannabis use was self-reported and not experimentally controlled; 1-year follow-up may miss later conversions; the sex-specific latency finding needs replication.
How to read the evidence
Large prospective cohort from a well-established consortium (NAPLS), with replication of age-PPI findings from a prior sample.
When this study was published
Published in 2020.
The bigger picture
The opposite pattern of cannabis effects on sensory gating in at-risk vs. healthy individuals suggests that cannabis interacts with already-altered brain circuits in people vulnerable to psychosis, rather than simply impairing everyone equally.
Questions still open
- Why do at-risk cannabis users show enhanced rather than reduced sensory gating? Could startle latency be used clinically to identify females at highest conversion risk?
Common questions
Did cannabis use predict psychosis in this study?
What is prepulse inhibition and why does it matter?
Read the original research
Evidence of Slow Neural Processing, Developmental Differences and Sensitivity to Cannabis Effects in a Sample at Clinical High Risk for Psychosis From the NAPLS Consortium Assessed With the Human Startle Paradigm.
Frontiers in psychiatry, 11, 833
Citation
Cadenhead, Kristin S; Duncan, Erica; Addington, Jean; Bearden, Carrie; Cannon, Tyrone D; Cornblatt, Barbara A; Mathalon, Dan; McGlashan, Thomas H; Perkins, Diana O; Seidman, Larry J; Tsuang, Ming; Walker, Elaine F; Woods, Scott W; Bauchman, Peter; Belger, Ayse; Carrión, Ricardo E; Donkers, Franc; Johannesen, Jason; Light, Gregory; Niznikiewicz, Margaret; Nunag, Jason; Roach, Brian. (2020). Evidence of Slow Neural Processing, Developmental Differences and Sensitivity to Cannabis Effects in a Sample at Clinical High Risk for Psychosis From the NAPLS Consortium Assessed With the Human Startle Paradigm.. Frontiers in psychiatry, 11, 833. https://doi.org/10.3389/fpsyt.2020.00833
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