Why Teens Started Using Cannabis Predicted Their Schizophrenia Risk and Severity | Research

The takeaway

The reasons adolescents gave for starting cannabis use - sedation, stimulation, social pressure, or recreation - predicted both their risk of developing schizophrenia-spectrum disorder and the severity of their symptoms.

Psychiatrists, adolescent health providers, psychosis prevention researchers.

Four distinct motives for adolescent cannabis use (sedation, stimulation, social pressure, recreation) formed a hierarchical structure predicting schizophrenia risk.

What the researchers found

Factor analysis of cannabis use motives produced four groups (sedation, stimulation, social pressure, recreation). These motive factor scores significantly predicted schizophrenia-spectrum disorder risk and schizotypal symptom severity. The factors followed a hierarchical structure explaining their relative involvement in SSD risk.

Why it matters

If the reasons for starting cannabis use can predict psychosis risk, this offers a potential screening tool. Rather than simply asking "do you use cannabis," clinicians could assess why someone uses to better identify who is at highest risk.

The numbers in context

178 participants total: healthy controls with cannabis use and schizophrenia patients with cannabis use. Four motive factors identified: sedation, stimulation, social pressure, and recreation.

How the study worked

178 participants in two samples: healthy controls with cannabis use and schizophrenia patients with cannabis use. Structured interviews with participants and family informants assessed diagnostic information, cannabis use motives, and clinical measures.

What this study cannot tell us

Cross-sectional design limits causal conclusions. Retrospective recall of motives may be inaccurate. No assessment of cannabis potency, frequency, or duration. Relatively small sample for factor analysis.

How to read the evidence

Moderate - novel finding with appropriate statistical methods, but cross-sectional with retrospective motive reporting.

When this study was published

Published in 2018.

The bigger picture

This study suggests that not all adolescent cannabis use carries the same risk. The motivation behind use may reflect underlying neurobiological differences that predispose certain individuals to psychosis, offering a more nuanced view than "cannabis causes schizophrenia."

Questions still open

Do certain motives for cannabis use reflect pre-existing neurobiological vulnerability? Could motive-based screening identify at-risk individuals before psychosis onset? Would the same motive patterns predict risk in larger, prospective studies?

Common questions

Does it matter why teens start using cannabis?

This study found that the reasons for starting cannabis use - whether for sedation, stimulation, social pressure, or recreation - predicted schizophrenia risk and symptom severity. This suggests not all cannabis use carries the same risk.

Can you predict who will develop psychosis from cannabis use?

This study found that motives for initiating cannabis use in adolescence predicted both schizophrenia risk and symptom severity. The researchers propose this could form the basis of a screening model for at-risk individuals.

Read the original research

Patterns in adolescent cannabis use predict the onset and symptom structure of schizophrenia-spectrum disorder.

Schizophrenia research, 197, 539-543

View on PubMed ↗Publisher’s paper ↗

Citation

Shahzade, C; Chun, J; DeLisi, L E; Manschreck, T C. (2018). Patterns in adolescent cannabis use predict the onset and symptom structure of schizophrenia-spectrum disorder.. Schizophrenia research, 197, 539-543. https://doi.org/10.1016/j.schres.2018.01.008