This paper has some of the Latest US study for 2022. (Executive Summary)
A difference-in-means test demonstrates that cannabis use is higher among all age groups in more highly permissive states, with 47 percent more monthly cannabis use among adolescents (ages 12-17) and 81 percent more monthly cannabis use among young adults (ages 18-25) in US states with fully legalized recreational cannabis programs than states where cannabis use has not been legalized. While cannabis use grew, subsequent raises in mean averages for major depressive events, severe mental illnesses, and suicidal thoughts all increased in more highly permissive US states.
The research results presented in this study demonstrate that for each one percent increase in overall monthly cannabis use, self-reported major depression increased by 0.45 percent for adolescents and 0.21 percent for young adults. For every one percent increase in overall monthly cannabis use by young adults, severe mental illnesses increased by 0.12 percent and suicidal thoughts increased by 0.11 percent. Panel regression models included control variables for gender, marital status, educational attainment, veteran status, unemployment status, race, and ethnicity.
On study of more than 8,500 cannabis products marketed online by more than 650 cannabis dispensaries in four western (CA, CO, NM, WA) and five northeastern (ME, MA, NH, RI, VT) states found the average medicinal cannabis product was advertised with a 19.2 percent THC concentration and the average recreational cannabis product was advertised with a 21.5 percent THC concentration (Cash et al., 2020). A Dutch paper showed THC levels above 15 % THC is as dangerous as cocaine.