Can the THC concentration predict the number of patients with cannabis-related diagnoses?

The use of high-potency cannabis products is associated with an increased risk of mental disorders. This study investigates whether the rising THC concentration in Germany is associated with an increase in cannabis-related diagnoses.

The number of insured persons with at least one cannabis-related ICD-10 F12 diagnosis (e.g., harmful use, dependence) in outpatient care was provided by statutory health insurance funds between 2009 and 2021. The dependent variable is the ratio of (a) the number of insured persons with at least one F12 diagnosis to (b) all insured persons who have used cannabis in the last year. Information on THC concentration in cannabis flower was provided by law enforcement agencies. Using generalised mixed linear models, the dependent variable was predicted by the median THC concentration in cannabis flower.

The regression results show that an increase in THC concentration by one percentage point is significantly associated with an increase in the proportion of diagnoses (women: +0.17; men: +0.42). THC concentration positively predicted the proportion of diagnoses in all 16 federal states for men and in 15 federal states for women.

Compared to low-potency products, using high-potency products may pose additional health risks, which may be particularly pronounced in men. Acknowledging the limitations of the ecological study design and uncertainties inherent to the analysed data, further investigations on the sex-specific impact of THC exposure are required. Limiting the THC concentration in cannabis products and closely monitoring THC consumption in the population appears necessary.