Background: Cross-sectional studies have suggested inhalant use is associated with psychosis. This association was examined in a longitudinal study accounting for other substance use and potential confounders.
Methods: We used a prospective sample (N = 6542) from the Northern Finland Birth Cohort 1986. Self-report questionnaires on substance use and psychotic experiences were completed when the cohort members were 15-16 years old. Inhalant use was categorized into four groups (never, once, 2-4 times, 5 times or more). Subsequent psychosis diagnoses (ICD-10) until age 30 years were obtained from national registers. Cox regression analysis was used to examine the association between adolescent inhalant use and risk of psychosis.
Results: During the observation period 124 individuals were diagnosed with incident psychosis. Overall, there were 225 (3.4%) subjects with any inhalant use, 18 (8.0%) of whom were diagnosed with psychosis during the follow up. Of non-inhalant users (n = 6317) 106 (1.7%) were diagnosed with psychosis. Compared to non-users, those using inhalants had increased risk of incident psychosis with most frequent inhalant use associated with the greatest risk (unadjusted HR = 9.46; 3.86-23.20). After adjusting for baseline psychotic experiences, other substance use, comorbid mental disorder and parental substance abuse, the increased risk of psychosis persisted (HR = 3.06; 1.05-8.95). Furthermore, a dose-response effect between inhalant use and risk of psychosis was identified (OR = 2.34; 1.83-2.99).
Conclusions: Inhalant use in adolescence was independently associated with incident psychosis. The adverse health outcomes associated with adolescent inhalant use provide compelling reasons for implementation of policies to reduce the use of volatile substances in adolescents.
Keywords: Birth cohort; Psychotic disorders; Schizophrenia; Substance abuse.
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