Brain cannabinoid CB 1 receptors contribute to alcohol-related behaviors in experimental animals, but their potential role in humans with alcohol dependence is poorly understood. We measured CB 1 receptors in alcohol dependent patients in early and protracted abstinence, and in comparison with control subjects without alcohol use disorders, using positron emission tomography and (18 F)FMPEP-d 2, a radioligand for CB 1 receptors. We scanned 18 male in-patients with alcohol dependence twice, within 3-7 days of admission from ongoing drinking, and after 2-4 weeks of supervised abstinence. Imaging data were compared with those from 19 age-matched healthy male control subjects. Data were also analyzed for potential influence of a common functional variation (rs2023239) in the CB 1 receptor gene (CNR1) that may moderate CB 1 receptor density. On the first scan, CB 1 receptor binding was 20-30% lower in patients with alcohol dependence than in control subjects in all brain regions and was negatively correlated with years of alcohol abuse. After 2-4 weeks of abstinence, CB 1 receptor binding remained similarly reduced in these patients. Irrespective of the diagnostic status, C allele carriers at rs2023239 had higher CB 1 receptor binding compared with non-carriers. Alcohol dependence is associated with a widespread reduction of cannabinoid CB 1 receptor binding in the human brain and this reduction persists at least 2-4 weeks into abstinence. The correlation of reduced binding with years of alcohol abuse suggests an involvement of CB 1 receptors in alcohol dependence in humans.
Bibliographical noteFunding Information:
We thank Kimberly Jenko, Kacey Anderson and David Clark for assisting in the measurements of radioligand in plasma; Maria D Ferraris Araneta, Gerald Hodges, William C Kreisl and Barbara Scepura as well as Chris Geyer and the NIAAA nursing staff for subject recruitment and care; the NIH PET Department for imaging; and the PMOD Technologies for providing its image analysis and modeling software. This research was supported by the Intramural Programs of NIMH and NIAAA. Jussi Hirvonen was supported by personal grants from The Academy of Finland; The Finnish Cultural Foundation; The Finnish Foundation for Alcohol Studies; The Finnish Medical Foundation; The Instrumentarium Foundation; The Jalmari and Rauha Ahokas Foundation; The Paulo Foundation; The Research Foundation of Orion Corporation; and The Yrjö Jahnsson Foundation.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Psychiatry and Mental health
- Cellular and Molecular Neuroscience