M90. CANNABIS USE, CIGARETTE SMOKING, AND PSYCHOTIC EXPERIENCES IN ADOLESCENCE AND DIAGNOSIS OF PSYCHOSIS IN EARLY ADULTHOOD. A BIRTH-COHORT STUDY
Authors: Peltonen Teemu , Mustonen Antti , Koskela Jari , Miettunen Jouko , Veijola Juha , Niemelä Solja 
Published: May 2020

Abstract

Background
Recent studies indicate that adolescent cannabis use (1) and cigarette smoking (2) increase the risk for psychosis. However, less is known about symptom profile associated with cannabis use and cigarette smoking prior to the psychotic episodes. Our aim was to study the associations between daily smoking, life-time cannabis use, and psychotic experiences in adolescence, and their relationship with psychotic disorders in early adulthood.

Methods
The Northern Finland Birth Cohort 1986 study includes 99% of all births (n=9432) in the region. At age 15–16, data on self-reported daily cigarette smoking and cannabis use was gathered using questionnaires. Psychotic experiences during past 6 months were evaluated using PROD-screen (3). Psychiatric diagnoses were collected from four Finnish nationwide health-care registers until year 2016, when participants were 30–31 years old. Individuals with information on daily smoking, cannabis use and psychotic experiences (n=6037, 47.7% male, 64.0% of the total cohort) were included. Associations were studied using multivariate logistic regression analysis.

Results
At age 15–16, 12.5% (n=755) reported daily smoking, and 5.6% (n=340) reported lifetime cannabis use and 30.9% (n=1868) were PROD-screen positive, i.e. reporting ≥3 symptoms on the PROD-screen. At age 30–31, 1.8% (n=111) of the participants had a register-based psychosis diagnosis. Individuals with subsequent psychosis reported more daily smoking (24.3%), cannabis use (15.3%) and psychotic experiences (51.4%) in adolescence than did individuals without any psychiatric diagnosis (11.1%, 4.6% and 28.6%).
The multivariate logistic regression analyses included sex, daily smoking, lifetime cannabis use, drug use other than cannabis and parental psychosis. Among those with psychosis during the follow-up, cannabis use at age 15–16 associated with positive PROD-screen (OR=5.0, 95%CI 1.1–22.1, p=0.033), ‘experience of thoughts running wild or difficulty in controlling the speed of thoughts’ (OR=5.0, 95%CI 1.2–20.9, p=0.026), and ‘depression, apathy, loss or energy or marked tiredness’ (OR 5.3, 95%CI 1.3–22.3, p=0.021). In the same group, daily smoking was inversely associated with ‘disorders in connection with vision, such as blurred vision, visual oversensitivity or changing visual perceptions’ (OR=0.1, 95%CI 0.02–0.8, p=0.028).
Among those without later psychiatric diagnosis, cannabis use associated with positive PROD-screen and PROD-items indicating anxiety, bodily restlessness, depression, difficulty completing tasks, difficulty thinking clearly, difficulty controlling the speed of thoughts, feelings of strange things happening, feelings, thoughts or behaviors that could be considered weird and feelings of being followed or influenced. In the same group, daily smoking was associated with bodily restlessness and depression.

Discussion
Lifetime cannabis use in adolescence is associated with psychotic experiences in individuals with or without subsequent psychosis. In those with subsequent psychosis, cannabis use had smaller impact on symptom profile. The inverse association between visual hallucinations and daily smoking in adolescence among individuals with subsequent psychotic disorder is a novel finding and needs further exploring.

References
1. Marconi A et al. Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis. Schizophr. Bull. 2016 Sep;42(5):1262–9
2. Gurillo P et al. Does tobacco use cause psychosis? Systematic review and meta-analysis. Lancet Psychiatry. 2015;2(8):718–25.
3. Heinimaa M et al. PROD-screen – a screen for prodromal symptoms of psychosis. Int J Meth Psych Res. 2003 Jun;12(2):92–104.