German Legalization Study Tracks Real Time Cannabis Use Patterns

Study Design and Participants

Researchers used Ecological Momentary Assessment (EMA) to track daily cannabis use among non-medical consumers in Germany before and after recreational cannabis decriminalization in April 2024. The final sample consisted of 49 participants, including 31 men, 17 women, and one non-binary individual, ranging in age from 20 to 60 years with a mean of 33.8.

Participants reported their consumption in real time via smartphone, a method the study authors said enhances ecological validity compared with retrospective assessments. During the pre-legalization phase, 61 participants provided daily information, with overall compliance to daily EMA prompts of 80 ± 20.3%.

Post-legalization, 49 participants provided daily cannabis consumption information, and compliance rates in that phase were 84.3 ± 20.4%. The study noted that real-time data on how legal reforms influence cannabis consumption remain scarce globally.

Key Findings After Legalization

Following the legal reform, the study observed a selective increase in consumed amounts among younger individuals (β = 0.01, 95%CI = 0.00 0.02, z = 3.05). Consumed amounts increased in outdoor settings (β = 0.19, 95%CI = 0.04 0.34, z = 2.51) but decreased in public settings (β = -0.46, 95%CI = -0.66 – -0.25, z = -4.36).

Consumption was also more likely to occur on holidays (β = 3.91, 95%CI = 1.68 9.08, z = 3.17).

The researchers had hypothesized an overall increase in cannabis use following the legal reform, based on recent findings, and expected a shift toward outdoor and public settings due to a reduction in perceived criminalization. The findings on public settings did not match that expectation.

Policy Context and Implications

As of April 2024, Germany allowed adults aged 18 and older to possess up to 25 g of cannabis in public and 50 g at home, and to cultivate up to three cannabis plants. Since January 2025, certain previous convictions related to cannabis offenses that are no longer illegal have been removed from criminal records.

The study authors stated that by capturing the immediate post-legalization period, the research contributes early insights to inform prevention, treatment, and regulation. They noted that cannabis ranks third in global psychoactive substance prevalence after nicotine and alcohol, and that heavy use is linked to psychosis, anxiety, and depression.

The researchers also examined whether cannabis use began to resemble alcohol patterns, noting that prior EMA studies have shown alcohol consumption increases on weekends and public holidays. The study is published in Scientific Reports, Article number 27818.

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