As we have learned more about the role genes play in our health, researchers have discovered that different factors can alter the expression of our genes. This field is called epigenetics.
Scientists are learning more and more about how epigenetics can affect our risk for developing AUD. Scientists are also exploring how genes may influence the effectiveness of treatments for AUD. Learning more about the genetic, epigenetic, and neurobiological bases of addiction will eventually advance the science of addiction. Scientists will be able to translate this knowledge into new treatments directed at specific targets in the brain or to treatment approaches—called pharmacogenomics.
This emerging science promises to harness the power of genomic information to improve treatments for addiction by tailoring the treatment to the person's specific genetic makeup.
This is called precision medicine. By knowing a person's genomic information, health care providers will be better equipped to match patients with the most suitable treatments and medication dosages, and to avoid or minimize adverse reactions. The mission of the NIDA's Division of Neuroscience and Behavior DNB is to advance the science of drug use and addiction through basic and clinical biomedical neuroscience and behavioral research.
The DNB's Genetics, Epigenetics, and Developmental Neuroscience Branch supports research on the genetics, epigenetics, and developmental mechanisms that underlie substance use, misuse, and addiction. The DNB accomplishes its mission by developing and supporting an extramural research program that provides an understanding of the neurobiological and behavioral mechanisms of drugs of abuse and its consequences.
This publication is available for your use and may be reproduced in its entirety without permission from NIDA.
Department of Health and Human Services. National Institutes of Health. Drug Topics. More Drug Topics. Quick Links. About NIDA. Genetics and Epigenetics of Addiction DrugFacts. Research Advance: Genes Involved in Addiction An international group of over scientists used a comprehensive database to collect information on smoking and alcohol use behaviors.
Changes in genes, known as mutations, cause diseases in people. Gene sequencing is an extremely powerful tool because it can find a connection between a known gene or genes and a disorder, and can identify genes that may have been overlooked or were previously unknown.
Figure 1. Note: single-headed arrows represent standardized factor loadings, double-headed arrows represent total variance for the Problem drinking factor and residual variances for all other factors depicted in the figure. Factor loadings of 1 are fixed parameters, the factor loadings of problem drinking on CAGE and AUDIT are constrained to be equal; these constraints ensure that the factor model is identified.
In the univariate saturated model for problem drinking, and in the five bivariate saturated models we estimated the mean and covariance structure for problem drinking and each of the five personality scales in twins and siblings. There were no significant sex differences in means for Extraversion, Openness to Experience, and Conscientiousness. The phenotypic correlations were relatively low but all significant ranging between 0. Somewhat lower correlations were seen for the other personality traits, where those who scored highest on Neuroticism, Extraversion, and Openness to Experience scored highest on problem drinking.
Table 2. Means, variances, and phenotypic correlations for problem drinking and the FFM personality scales as obtained from the saturated models.
When constrained over sexes, the MZ correlation for problem drinking 0. For all five personality traits, the MZ correlation is larger than twice the DZ correlation, suggesting that both additive and non-additive influences play a role in explaining variation in personality.
Shared environmental influences do not seem to explain variation in personality. Table 3. This general pattern of MZ and DZ cross correlation suggests that the small but significant correlations between problem drinking and the FFM personality scales can be explained by overlapping genetic factors.
The estimates of the proportions of variance due to A , D , and E for each phenotype are given in the upper part of Table 4. The univariate genetic model for problem drinking showed that the heritability of problem drinking was Based on the results from the bivariate saturated models and consistent with the results from an earlier study on the FFM of personality Distel et al.
Because the univariate analysis indicated no impact of non-additive genetic influences for problem drinking, these influences were set to zero for problem drinking. As a result, overlapping non-additive genetic influences were also not possible. For Neuroticism, Openness to Experience, and Conscientiousness a scalar was added in female twins and siblings to account for the significant differences in the phenotypic variances across sex.
The broad-sense heritabilities of the FFM personality scales ranged between The broad-sense heritability for Neuroticism Similar estimates are obtained for Extraversion broad-sense heritability Table 4. Proportions of variance and the phenotypic correlations explained by genetic and environmental factors and genetic and environmental correlations as obtained from the genetic models for problem drinking and personality.
The estimates of the proportions of the phenotypic correlations due to A and E and the additive genetic and unique environmental correlations are provided in the lower part of Table 4.
A large part of the correlations between problem drinking and the FFM of personality can be explained by additive genetic influences, with proportions of the phenotypic correlations ranging from Since it is more likely that the small negative environmental correlation results from sampling error in the estimates of the twin correlations rather than from truly environmental factors that have opposite effects on problem drinking and Openness and Experience, we also fitted a model in which the environmental correlation was constrained at zero.
The estimate of the genetic correlation is almost the same 0. The relatively large genetic correlations for Neuroticism 0. Therefore, we also estimated the genetic correlations in a series of AE models. The genetic correlations for Neuroticism, Extraversion, and Conscientiousness with problem drinking were indeed somewhat lower 0.
This study reports on the factor structure of the AUDIT and CAGE problem drinking measures in a large population-based sample and examined the heritability of problem drinking and its genetic relationship with personality traits assessed with the NEO. The study was conducted in a sample of 10, twins, siblings, and additional family members from the NTR. The DZ twin correlation was not different from the twin—sibling or sibling—sibling correlation, which suggests that there is no special twin environment and that results from heritability studies on problem drinking in adult twins can be generalized to the non-twin population.
Further, we did not find evidence for sex differences in heritability of problem drinking. This is in line with heritability estimates reported in previous twin studies e. The correlations between the problem drinking factor score and the FFM dimensions of personality were small but significant, ranging from 0.
These results indicate that the genetic factors found for problem drinking partly represent genetic factors for personality, with each of the FFM personality scales contributing a small amount to these genetic factors. The results on the phenotypic and genetic overlap between problem drinking and personality are largely consistent with earlier multivariate twin studies on the relationship between alcohol phenotypes and personality Jang et al.
The effect sizes in our study and those found in Littlefield et al. For example, in the study from Jang et al. They report genetic correlations with alcohol misuse that range from 0.
Mustanski et al. Genetic correlations ranged between 0. In the study from Slutske et al. These three higher-order personality dimensions were based on a factor analysis of the Tridimensional Personality Questionnaire and the Eysenck personality Questionnaire. The largest genetic correlations 0. Somewhat lower genetic correlations were found for positive and negative emotionality 0. In the single previous study on alcohol use disorder symptoms and the FFM of personality, conducted in female twin pairs Littlefield et al.
Our study adds to the study of Littlefield et al. To conclude, we largely corroborate the findings of previous studies by showing that alcohol use disorders are genetically correlated with both the internalizing e. The phenotypic and genetic correlations were based on the assumption of a linear relationship between problem drinking and personality.
This assumption could be challenged as the relationship between alcohol consumption and personality traits such as neuroticism and depressive symptoms is non-linear Rodgers et al.
We examined this by regressing the problem drinking factor scores on each of the personality traits in a model which included linear and quadratic relationships. For example, for Agreeableness and Conscientiousness it was found that the increase in problem drinking becomes stronger with increasingly low levels of Agreeableness and Conscientiousness. This means that individuals who score very high, high, or intermediate on Agreeableness and Conscientiousness do not differ much in problem drinking, but individuals who score low or very low on these personality traits show the highest scores for problem drinking.
Similar effects were observed for the other personality traits, where those who score highest on Neuroticism, Extraversion, and Openness to Experience score highest on problem drinking. Thus, the estimated linear correlations reported in this study capture only part of the true strength of the associations between personality and problem drinking. Current genetic models are not able to incorporate these non-linear relationships, but may be developed in the future.
Recently, a number of GWA studies came out that attempted to identify the actual genetic variants that underlie personality and alcohol use disorders; Shifman et al. Two of these studies yielded genome-wide significant hits, one for personality De Moor et al. The genome-wide significant hits account for a very small portion of the heritabilities of the phenotypes. In the meta-analysis for personality, including more than 17, individuals, three genome-wide significant hits were found; two hits for Openness to Experience in an intergenic region on chromosome 5 and one hit for Conscientiousness in the brain-expressed KATNAL2 gene on chromosome In the meta-analysis for alcohol consumption, comprising of 26, individuals in the discovery stage and 21, individuals in the replication stage, a genome-wide significant hit was found in the AUTS2 gene on chromosome 7.
Gene expression analysis in human brains and animal experiments were consistent were the role of this gene to drinking behavior Schumann et al. To conclude, we showed that in a large general population sample problem drinking is heritable and that there is small to modest genetic overlap between problem drinking and all five dimensions of the FFM of personality. This overlap seems largest for Neuroticism and Conscientiousness.
Future studies with longitudinal data and DNA polymorphisms in large collaborative samples are needed to pinpoint to the causal and biological mechanisms that underlie the genetic link between internalizing and externalizing personality and alcohol use disorders.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Alati, R. Findings from the Mater-University Study of Pregnancy and its outcomes. Addiction , — Bierut, L. A genome-wide association study of alcohol dependence. The catalyst that leads to alcohol abuse is very often an environmental factor, such as work-related stress.
The more risk factors a person has, the greater the chance of developing an alcohol use disorder or addiction. Risk and protective factors are either environmental or biological. Some environmental factors that are particularly risky for those who are genetically inclined towards alcoholism include:.
Make a Call Those with a history of alcoholism in their family have the highest risk of becoming alcoholics.
If you have multiple relatives with alcohol addictions or other substance use disorders, you may have inherited the genes that put you at risk.
The more family members related by birth you have with an alcohol problem, the higher your risk. Just because someone may have a strong susceptibility toward alcoholism does not mean they are resigned to that fate. No one can control their genetic makeup, but everyone can take measures to prevent an addiction.
According to research, some of the best ways to stop a genetic predisposition from becoming a full-on alcohol addiction include:. Counseling and support can help tackle social and environmental factors that could contribute to an alcohol problem in the future.
If you or a loved one has already developed a problem, there are outpatient and inpatient programs that can help. Contact a treatment provider to discuss your options. After graduation, he decided to pursue his passion of writing and editing. All of the information on this page has been reviewed and verified by a certified addiction professional. Theresa is also a Certified Professional Life Coach and volunteers at a local mental health facility helping individuals who struggle with homelessness and addiction.
Theresa is a well-rounded clinician with experience working as a Primary Addiction Counselor, Case Manager and Director of Utilization Review in various treatment centers for addiction and mental health in Florida, Minnesota, and Colorado.
She also has experience with admissions, marketing, and outreach. As a proud recovering addict herself, Theresa understands first-hand the struggles of addiction.
There is no limit to what Theresa is willing to do to make a difference in the field of Addiction! Annandale, VA. View Center. Milford, DE.
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