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J Adolesc Health. 2017 Jun;60(6):653-659. doi: 10.1016/j.jadohealth.2017.01.006. Epub 2017 Mar 17.

Cannabis Use, Polysubstance Use, and Psychosis Spectrum Symptoms in a Community-Based Sample of U.S. Youth.

Author information

1
Neuropsychiatry Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: jasjones@upenn.edu.
2
Neuropsychiatry Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
3
Neuropsychiatry Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; VISN 4 Mental Illness Research, Education, and Clinical Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.
4
Neuropsychiatry Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: raquel@upenn.edu.

Abstract

PURPOSE:

To examine how cannabis use and polysubstance use among cannabis users relate to psychosis spectrum (PS) symptoms in a large community-based sample of U.S. youth.

METHODS:

Four thousand one hundred seventy-one youths (aged 14-21 years; mean = 16.90 years, SD = 1.85; 55% female) from the Philadelphia Neurodevelopmental Cohort completed assessments of substance use, PS symptoms, and confounding variables (e.g., demographics, comorbid psychopathology, and trauma exposure).

RESULTS:

After adjusting for confounds, cannabis use by itself was not associated with increased odds of being classified as "psychosis spectrum." However, cannabis use in combination with tobacco or other substance use was associated with increased odds of PS classification (adjusted odds ratios [ORs] = 1.37-1.76). Follow-up symptom-level analyses revealed that cannabis use in combination with other substances was associated with subclinical positive symptoms (ORs = 1.95 and 2.24) and frequent cannabis use was associated with subclinical negative/disorganized symptoms (OR = 2.14). However, these symptom-level findings were reduced to trends after correction for multiple comparisons. Neither cannabis use nor polysubstance use was associated with threshold delusions or hallucinations.

CONCLUSIONS:

After adjusting for important confounds, there was minimal evidence for associations between cannabis use by itself and PS symptoms. More compelling evidence emerged for associations between polysubstance use among cannabis users and PS symptoms. This study highlights the importance of considering polysubstance use and confounds when examining associations between cannabis use and PS symptoms. Further longitudinal research is necessary to determine whether these findings represent causal associations or shared genetic and/or environmental vulnerability for substance use and PS symptoms.

KEYWORDS:

Cannabis; Marijuana; Philadelphia Neurodevelopmental Cohort; Polysubstance; Psychosis; Schizophrenia

PMID:
28318911
PMCID:
PMC5441952
DOI:
10.1016/j.jadohealth.2017.01.006
[Indexed for MEDLINE]
Free PMC Article

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