A recently published study provides interesting results from a survey studying the effects of cannabis legalization in California.

California became the first US state to allow medicinal cannabis use in 1996. Then in 2016 the state’s voters legalized recreational use through Proposition 64: The Adult Use of Marijuana Act.

Researchers from UC San Diego and analysts from market research firm Quester set out to document patterns of use of cannabis containing the cannabinoid tetrahydrocannabinol (THC) among adults 21 years and older in California since then, in a study titled “Impact 64”.

An online questionnaire was administered from December 2022 to February 2023. From an initial sample of 15,208 respondents, a  subset of participants completed a detailed cannabis use questionnaire, including 4,020 current cannabis users.

Among the findings:

• 37% reported current cannabis use (within the past 3 months).
• 30% formerly used cannabis.
• 33% were nonusers.
• 38% of current users reported very frequent use (multiple times a day).
• 33% cited frequent use (four times per week to daily).
• 30% were engaged in occasional use (three times per week or less).
• The most commonly used products were flower (56%), edibles or capsules (50%) and vaping concentrates (36%).
• Positive impacts were reported in mental (82%), emotional (81%), and physical (62%) health.
• The most commonly reported negative effects were brain fog (21%) and lack of motivation (21%).
• Most users were sourcing products from perceived licensed dispensaries or delivery services, while 12% grew their own.

78% of current users felt comfortable discussing cannabis with their primary doctor, but only 66% of primary doctors knew about their recreational use. Commenting on this result, the researchers said:

“While patients claimed comfort in discussing cannabis generally with health providers, disclosure was less frequent, and providers were not seen as a primary source of cannabis-related information.”

Principal investigator of Impact 64, Professor Linda Hill, M.D., M.P.H said:

“It’s clear that a large portion of the population is using cannabis, but there are significant gaps in knowledge regarding laws and safety, and physicians are rarely consulted for advice on use. We need more targeted education initiatives for both cannabis users and medical providers.”

The full Impact 64 study has been published in the journal Cannabis and Cannabinoid Research.