In Poland, alcohol dependence (AD) affects about four percent of the population, causing about 10,000 deaths per year.
While a number of biological markers have been linked to a predisposition for developing AD, a new study has found a link between the Val66Met (rs6265) polymorphism in the brain-derived neurotrophic factor (BDNF) gene and risk for post-treatment relapse among AD patients.
Results will be published in the April issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"Some people are simply more likely than others to become dependent on alcohol," explained Marcin Wojnar, associate professor of psychiatry at the Medical University of Warsaw and adjunct researcher at the University of Michigan. "Clearly, cultural, social, and psychological factors are involved. AD also runs in families, so there is an inherited component to it. Once AD has developed, certain people are more likely to relapse after treatment than others. Some studies show that a family history of alcoholism can lead to a more severe illness that is harder to treat, which is why our group and others are looking at genetic factors."
"Although some biological predictors of the re-emergence of AD have been described," said Lance Bauer, professor of psychiatry at the University of Connecticut School of Medicine, "biological measures can be affected by many variables, such as the time of day; the patient's gender, age, or medical background; or medications that have been prescribed. Most genetic differences are not complicated by these same variables. Accordingly, this study by Wojnar and colleagues points us toward a new and promising approach."
"We selected genetic polymorphisms that were, one, related to serotonin or dopamine function; and two, associated with suicidality and/or impulsivity," said Wojnar, who is the study's first author. "Serotonin's decreased functioning has consistently been reported to be associated with both impulsivity and suicidal behaviors. Regarding dopamine, most researchers agree that it plays an essential role in addiction, either by causing pleasure from taking drugs or by telling the brain to associate that pleasure with certain cues in the environment."
The researchers examined 154 patients (117 males, 37 females) from addiction-treatment programs in Poland who met Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition criteria for AD. All were assessed for demographics, severity of alcohol use, suicidality, impulsivity, depression, hopelessness, and severity of alcohol use at baseline; 123 patients were followed for approximately one year to evaluate treatment outcomes. In addition, patients were tested for genetic polymorphisms in several genes as predictors of relapse – defined as "any drinking during follow-up" – which were: rs1386483 in the tryptophan hydroxylase type 2 gene, C102T (rs6313) in the serotonin receptor 2A gene, 5-HTT gene-linked polymorphic region in locus SLC6A4, C(-1019)G (rs6295) in the serotonin receptor 1A gene, Val158Met (rs4680) in the catechol-O-methyl transferase gene, and the Val66Met (rs6265) in the BDNF gene.