No abstract

Self-disturbances constitute a hallmark of psychosis, but it remains unclear whether these alterations are present in at-risk populations, and therefore their role in the development of psychosis has yet to be confirmed. The present study addressed this question by measuring neural correlates of self-other processing in youth belonging to three developmental trajectories of psychotic experiences. Eighty-six youths were recruited from a longitudinal cohort of over 3800 adolescents based on their trajectories of Psychotic-Like Experiences from 12 to 16 years of age. Participants underwent neuroimaging at 17 years of age (mean). A functional neuroimaging task evaluating self- and other-related trait judgments was used to measure whole-brain activation and connectivity. Youth who showed an increasing trajectory displayed hypoactivation of the dorsomedial prefrontal cortex and hypoconnectivity with the cerebellum. By contrast, youth who showed a decreasing trajectory displayed decreased activation of the superior temporal gyrus, the inferior frontal gyrus, and the middle occipital gyrus. These findings suggest that the increasing trajectory is associated with alterations that might erode distinctions between self and other, influencing the emergence of symptoms such as hallucinations. The decreasing trajectory, in comparison, was associated with hypoactivations in areas influencing attention and basic information processing more generally. These alterations might affect the trajectories’ susceptibilities to positive vs. negative symptoms, respectively.

Objectives Increasing evidence implicates cannabis consumption as a key risk factor in the development of psychosis, but the mechanisms underpinning this relationship remain understudied. This study proposes to determine whether sleep disruption acts as a mediator of the cannabis-to-psychosis relationship. Study design This longitudinal study assessed measures of cannabis use frequency, sleep quality, and psychotic-like experiences were collected using self-reported questionnaires. Data were collected from September 2012 to September 2018. Data were collected from a general population sample of adolescents who entered the seventh grade in 31 schools in the Greater Montreal area. The study uses data collected on an annual basis from 3801 high school students from grades 7 to 11. The aforementioned measures were measured using the Detection of Alcohol and Drug Problems in Adolescents questionnaire, a sleep quality Likert scale, and measures the Adolescent Psychotic-Like Symptom Screener. Study results Results show a reciprocal one-year cross-lagged effect of cannabis use and sleep (β=-0.076, 95%CI=-0.037/-0.018, p=0.000), of sleep on cannabis use (β=-0.016, 95%CI=-0.025/-0.006, p=0.007), of sleep on psychotic-like experiences (PLEs) (β=-0.077, 95%CI=-0.014/-0.051, p=0.000), and of psychotic-like experiences on sleep (β=-0.027, 95%CI=-0.037/-0.018, p=0.000). We additionally found a two years indirect lagged-effect of cannabis use on psychotic-like experiences (β=0.068, 95%CI=0.024/0.113, p=0.011) mediated by one year sleep (β=0.006, 95%CI=0.003/0.009, p=0.001). Conclusions Our results suggest sleep disruptions simultaneously aggravate, and are aggravated by, cannabis addiction and psychotic-like experiences. The longitudinal sleep mediated effect of cannabis use on PLEs encourages further research into the role of sleep as a potential therapeutic target in the prevention of cannabis-related psychosis.