Lower brain fatty acid amide hydrolase in treatment-seeking patients with alcohol use disorder: a positron emission tomography study with [C-11]CURB

Endogenous neuromodulatory molecules are commonly coupled to specific metabolic enzymes to ensure rapid signal inactivation. Thus, acetylcholine is hydrolysed by acetylcholine esterase and tryptamine neurotransmitters like serotonin are degraded by monoamine oxidases. Previously, we reported the structure and sleep-inducing properties of cis-9-octadecenamide, a lipid isolated from the cerebrospinal fluid of sleep-deprived cats. cis-9-Octadecenamide, or oleamide, has since been shown to affect serotonergic systems and block gap-junction communication in glial cells (our unpublished results). We also identified a membrane-bound enzyme activity that hydrolyses oleamide to its inactive acid, oleic acid. We now report the mechanism-based isolation, cloning and expression of this enzyme activity, originally named oleamide hydrolase, from rat liver plasma membranes. We also show that oleamide hydrolase converts anandamide, a fatty-acid amide identified as the endogenous ligand for the cannabinoid receptor, to arachidonic acid, indicating that oleamide hydrolase may serve as the general inactivating enzyme for a growing family of bioactive signalling molecules, the fatty-acid amides. Therefore we will hereafter refer to oleamide hydrolase as fatty-acid amide hydrolase, in recognition of the plurality of fatty-acid amides that the enzyme can accept as substrates.

This study introduces the Penn Alcohol Craving Scale (PACS), which has been used in several clinical trials at the University of Pennsylvania's Treatment Research Center. The PACS is a five-item, self-report measure that includes questions about the frequency, intensity, and duration of craving, the ability to resist drinking, and asks for an overall rating of craving for alcohol for the previous week. Each question is scaled from 0 to 6. To examine the questionnaire's psychometric properties, we sampled responses from 147 individuals participating in a 9-month combined natrexone (100 mg/day)/psychotherapy trial. The psychotherapy consisted of weekly sessions of nurse-administered medication compliance and supportive treatment. The PACS proved to have excellent internal consistency. Predictive validity was demonstrated via a logistic regression analysis of craving during the 2nd week of the study on alcohol relapse during weeks 3-12 of the trial. Construct validity of the PACS was demonstrated via its convergence with two commonly used measures for assessing craving, the Obsessive Compulsive Drinking Scale and the Alcohol Urge Questionnaire. Lack of correlation between PACS scores and several other noncraving, self-report measures indicates that the PACS also had good discriminant validity. Additional analyses revealed that there were significant differences in craving scores during the initial 3 weeks of the trial among those who did and those who did not relapse during weeks 3-12. The PACS is a reliable and valid measure of alcohol craving and can predict which individuals are at risk for subsequent relapse.