Spirituality Associated with 13% Lower Risk of Hazardous Substance Use in 55-Study Meta-Analysis

The relationship between religious or spiritual engagement and substance use has generated decades of research but no prior systematic synthesis that follows people over time. Cross-sectional studies - those that compare spiritual and non-spiritual individuals at a single point - are common enough, but they cannot tell us whether spirituality precedes reduced substance use, or whether people who already use substances less tend to gravitate toward spiritual practices for other reasons. Longitudinal studies that track the same individuals across years are required to begin answering that question.

A meta-analysis published in JAMA Psychiatry, led by researchers at Harvard T.H. Chan School of Public Health, represents the first systematic effort to synthesize those longitudinal data at scale. The analysis pooled results from 55 published prospective studies and documented a consistent protective association between spirituality and harmful or hazardous substance use.

What the Analysis Covered

The 55 included studies tracked participants over time and measured both spiritual engagement and substance use outcomes, allowing the researchers to assess whether spiritual practice at one time point predicted reduced substance use risk at a later time point. Substances covered included alcohol, tobacco, marijuana, and illicit drugs. The definition of spirituality was intentionally broad: religious service attendance qualified, as did meditation, prayer, and other practices through which individuals report finding ultimate meaning or connection - whether or not those practices are affiliated with any formal religion.

Corresponding author Howard K. Koh, MD, MPH, of Harvard T.H. Chan School of Public Health led the analysis. The overall finding was a 13% reduction in hazardous or harmful substance use risk among individuals who engaged in spiritual practices compared to those who did not.

Religious Service Attendance Showed the Strongest Effect

Within the broad category of spiritual practices, the strongest association was with attending religious services at least once per week. Individuals who attended with that frequency showed an 18% reduced risk of hazardous substance use compared to non-attenders. The gradient across attendance frequencies - greater attendance associated with greater risk reduction - strengthens the case that the association is not simply reflecting confounding by some other characteristic that happens to correlate with both church attendance and lower substance use.

The mechanisms proposed in the literature include social support and accountability that come from religious community membership, the provision of alternative coping strategies for stress and negative emotion, normative influences against substance use within many religious communities, and the cultivation of meaning and purpose that may reduce reliance on substances as emotional regulation tools.

Causal Interpretation Remains Uncertain

Even with longitudinal data, establishing that spirituality causes reduced substance use is methodologically difficult. Randomized trials of spiritual practice are rarely feasible, which means researchers must rely on observational designs that cannot fully eliminate alternative explanations. People who choose to engage in spiritual practices differ from those who do not in numerous ways - personality traits, family background, socioeconomic status, baseline mental health - and these differences may account for part of the observed association regardless of the spiritual practice itself.

The meta-analysis addresses this to a degree by focusing on longitudinal evidence, but the included studies varied considerably in the confounders they controlled for. Some adjusted for relevant baseline characteristics; others did not. The pooled estimate of 13% risk reduction should therefore be interpreted as a measure of association rather than a causal effect size.

The researchers also note significant heterogeneity across studies - variation in populations studied, cultural contexts, definitions of spirituality, and substances measured - which affects the precision and generalizability of the pooled estimate.

Implications for Clinicians and Communities

The study's practical framing centers on clinical and community applications. For patients who identify as spiritual or religious, the findings suggest that clinicians might discuss spiritual practices as a complement to evidence-based addiction prevention and treatment, rather than treating spirituality as separate from healthcare. The authors are explicit that this applies to individuals for whom spirituality is already personally meaningful - not as a prescription for people without existing spiritual engagement.

At the community level, organizations providing addiction prevention and recovery services might consider how to leverage existing spiritual infrastructure - congregations, meditation centers, community religious organizations - as adjunct resources, particularly in settings where formal clinical services are scarce or face access barriers.

The study is published in JAMA Psychiatry (DOI: 10.1001/jamapsychiatry.2025.4816).