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Fatty acid amide hydrolase is lower in young cannabis users.

  • Jacobson, Maya R1, 2, 3
  • Watts, Jeremy J1, 2, 3
  • Da Silva, Tania1, 3
  • Tyndale, Rachel F2, 4, 3
  • Rusjan, Pablo M1, 4, 3
  • Houle, Sylvain1, 4, 3
  • Wilson, Alan A1, 4
  • Ross, Ruth A2
  • Boileau, Isabelle1, 4, 3
  • Mizrahi, Romina1, 2, 4, 3
  • 1 Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada. , (Canada)
  • 2 Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada. , (Canada)
  • 3 Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada. , (Canada)
  • 4 Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada. , (Canada)
Published Article
Addiction Biology
Wiley (Blackwell Publishing)
Publication Date
Jan 01, 2021
DOI: 10.1111/adb.12872
PMID: 31960544


We have recently shown that levels of fatty acid amide hydrolase (FAAH), the enzyme that metabolizes the endocannabinoid anandamide, are lower in the brains of adult cannabis users (CUs) (34 ± 11 years of age), tested during early abstinence. Here, we examine replication of the lower FAAH levels in a separate, younger cohort (23 ± 5 years of age). Eighteen healthy volunteers (HVs) and fourteen CUs underwent a positron emission tomography scan using the FAAH radioligand [11 C]CURB. Regional [11 C]CURB binding was calculated using an irreversible two-tissue compartment model with a metabolite-corrected arterial plasma input function. The FAAH C385A genetic polymorphism (rs324420) was included as a covariate. All CUs underwent a urine screen to confirm recent cannabis use and had serum cannabinoids measured. One CU screened negative for cannabinoids via serum and was removed from analysis. All HVs reported less than five lifetime cannabis exposures more than a month prior to study initiation. There was a significant effect of group (F1,26 = 4.31; P = .048) when two A/A (rs324420) HVs were removed from analysis to match the genotype of the CU group (n = 16 HVs, n = 13 CUs). Overall, [11 C]CURB λk3 was 12% lower in CU compared with HV. Exploratory correlations showed that lower brain [11 C]CURB binding was related to greater use of cannabis throughout the past year. We confirmed our previous report and extended these findings by detecting lower [11 C]CURB binding in a younger cohort with less cumulative cannabis exposure. © 2020 Society for the Study of Addiction.

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