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Eye movements in patients in early psychosis with and without a history of cannabis use

Musa Basseer Sami, Luciano Annibale, Aisling O’neill, Tracy Collier, Chidimma Onyejiaka, Savitha Eranti, Debasis Das, Marlene Kelbrick, Philip Mcguire, Steven C. R. Williams, Anas A. Rana, Ulrich Ettinger, Sagnik Bhattacharyya

Schizophrenia May 12, 2021 DOI: 10.1038/s41537-021-00155-2 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational cross-sectional study Peer reviewed
Sample size 91
Population Patients in the early phase of psychosis and healthy controls, with and without a history of cannabis use
Topics Cannabis
Citations 5
Key findings Smooth pursuit velocity gain was significantly affected by cannabis use, patient status, and their interaction, with impairment more severe in early psychosis patients without a history of cannabis use (large effect, g = 0.76–0.86). No significant group effect was found for antisaccade error, though patients had fewer valid trials. The authors suggest that neurobiological alterations in psychosis may be less severe in patients whose illness developed in the context of cannabis use.

Abstract

Abstract It is unclear whether early psychosis in the context of cannabis use is different from psychosis without cannabis. We investigated this issue by examining whether abnormalities in oculomotor control differ between patients with psychosis with and without a history of cannabis use. We studied four groups: patients in the early phase of psychosis with a history of cannabis use (EPC; n = 28); patients in the early phase of psychosis without (EPNC; n = 25); controls with a history of cannabis use (HCC; n = 16); and controls without (HCNC; n = 22). We studied smooth pursuit eye movements using a stimulus with sinusoidal waveform at three target frequencies (0.2, 0.4 and 0.6 Hz). Participants also performed 40 antisaccade trials. There were no differences between the EPC and EPNC groups in diagnosis, symptom severity or level of functioning. We found evidence for a cannabis effect (χ2 = 23.14, p < 0.001), patient effect (χ2 = 4.84, p = 0.028) and patient × cannabis effect (χ2 = 4.20, p = 0.04) for smooth pursuit velocity gain. There was a large difference between EPC and EPNC (g = 0.76–0.86) with impairment in the non cannabis using group. We found no significant effect for antisaccade error whereas patients had fewer valid trials compared to controls. These data indicate that impairment of smooth pursuit in psychosis is more severe in patients without a history of cannabis use. This is consistent with the notion that the severity of neurobiological alterations in psychosis is lower in patients whose illness developed in the context of cannabis use.

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Study Year Design Participants
Cannabis use before age 15 and subsequent executive functioning 104 chronic cannabis users (49 early-onset before age 15, 55 late-onset after age 15)... 2011 Observational cross-sectional study n = 148
Patterns of simultaneous polysubstance use in drug using university students Drug-using university students 2006 Cross-sectional survey n = 149
Persisting Reductions in Cannabis, Opioid, and Stimulant Misuse After Naturalistic Psychedelic Use: An Online Survey Online survey respondents 2020 Cross-sectional survey
User perceptions of the benefits and harms of hallucinogenic drug use: A web-based questionnaire study Users of hallucinogenic drugs who completed a web-based questionnaire 2010 Cross-sectional survey n = 600
Illicit Use of LSD or Psilocybin, but not MDMA or Nonpsychedelic Drugs, is Associated with Mystical Experiences in a Dose-Dependent Manner Adults recruited from the MAPS website and newsletter, most reporting use of various... 2012 Cross-sectional survey n = 337

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