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. Author manuscript; available in PMC: 2015 Jun 1.
Published in final edited form as: Curr Addict Rep. 2014 Jun 1;1(2):115–128. doi: 10.1007/s40429-014-0018-7

Table 1. –Recent Epidemiological Studies.

Reference and Study Design Methods/Follow Up Sample Size Follow Up Result
Meier et al 2012 Longitudinal, prospective Cannabis use assessed at ages 18, 21, 26, 32, and 38 1,037 subjects from general population 38 years Decline in neuropsychological functioning in processing speed, memory, executive functioning, verbal comprehension
(Dunedin cohort) Neuropsychological testing at ages 13 and 38 8-point IQ decline in subjects with cannabis-dependence, onset in adolescence
Manrique-Garcia et al 2012 Longitudinal, prospective (Swedish military cohort) Annonymous survey at time of conscription (ages 18-19 for 93%) Interview and psychological assessment after 35 years 50,087 military conscripts (mandated), 93% were ages 18-19 at initiation of service 35 years The adjusted OR for the development of schizophrenia:

  • 3.7 (95% CI 2.3-5.8) in subjects who used cannabis >50 times v. non-users

  • 1.8 (95% CI 1.3-2.5) in subjects ever using cannabis v. non-users
Davis et al 2013 Cross sectional analysis (NESARC data set) Face-to-face, computer-assisted interview focusing on DSM-IV diagnoses 34,653 adults from general population NA The adjusted OR for schizotypal features:

  • 2.02 (95% CI 1.69-2.42) in subjects with lifetime cannabis use

  • 2.83 (95% CI 2.33-3.43) in subjects with lifetime cannabis abuse

  • 7.32 (95% CI 5.51-9.72) in subjects with lifetime cannabis dependence
The adjusted OR for psychotic disorder:

  • 1.27 (95% CI 1.03-1.57) in subjects with lifetime cannabis use

  • 1.79 (95% CI 1.35-2.38) in subjects with lifetime cannabis abuse

  • 3.69 (95% CI 2.49-5.47) in subjects with lifetime cannabis dependence

Kuepper, van Os, et al 2011 Longitudinal, prospective (German early development stages of psychopathology study) Cannabis use and psychosis assessed at baseline, 3.5, and 8.4 years using CIDI 1,923 adolescents/young adults (ages 14-24 at baseline) from general population 10 years OR for psychotic symptoms at 8.4y follow up:

  • 1.5 (95% CI 1.1-21) in subjects with lifetime cannabis use at 3.5y

  • 1.9, (95% CI 1.1-3.1) in subjects with new cannabis use at 3.5y
OR for cannabis use at 8.4y based on cannabis use at 3.5y: 0.8 (95% CI 0.6-1.2)
OR for persistent psychosis based on cannabis at baseline and 3.5y: OR 2.2 (95% CI 1.2-4.2)

OR = odds ratio; CI = confidence interval; CIDI = composite international diagnostic interview