Fatty acid amide hydrolase is lower in young cannabis users. (20th January 2020)

• Record Type: Journal Article
• Authors: Jacobson, Maya R.; Watts, Jeremy J.; Da Silva, Tania; Tyndale, Rachel F.; Rusjan, Pablo M.; Houle, Sylvain; Wilson, Alan A.; Ross, Ruth A.; Boileau, Isabelle; Mizrahi, Romina
• Is Part Of: Addiction biology. Volume 26:Number 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-20
• Subjects: [11C]CURB -- addiction -- anandamide -- cannabis -- fatty acid amide hydrolase -- positron emission tomography; Substance abuse -- Periodicals; Substance abuse -- Physiological aspects -- Periodicals; Substance-Related Disorders -- periodicals; 616.86
• DOI: 10.1111/adb.12872
• Languages: English
• ISSNs: 1355-6215

Abstract

Abstract: 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 ( F 1, 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 λk 3 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. Abstract : We used the novel PET radiotracer [ 11 C]CURB to measure brain levels of fatty acid amide hydrolase (FAAH), the catabolizing enzyme for anandamide, in cannabis users in early abstinence. [ 11 C]CURB binding was lower in the cannabis users compared with healthy controls. This report is an extension of a previous study, which first detected lower [ 11 C]CURB binding in cannabis users who were older and had more extensive cannabis use than those in the current sample.