The importance of genetic factors in determining an individual’s vulnerability to substance addiction has long been the object of scientific study. There seems to be a definite link between a number of common addictions – such as alcohol for example – and an inherited genetic predisposition. Environmental factors (social and familial) also play a big role. These influence a person’s conditioning, and contribute to how they behave around substances and their recreational use.
Do genes alone explain why some people are safe around cigarettes or alcohol, while others may struggle much of their lives to control their use of them or to break free of addiction? The field of epigenetics is the study of how environment and behavior affect how genes work. The implications are that just because someone’s genes increase their proclivity to addiction, does not mean these genes will actively express themselves. The fact remains that the genetics behind addictive behaviors are extremely complex, and countless individuals currently still suffer from the behavioral traits their genes have imposed on them. However, the study of genetic diversity, among subjects with varying degrees of addictive tendencies, holds great promise regarding the development of new therapies for addiction.
Is There an Addiction Gene?
In order to investigate this question, scientists study genomes. Genomes are sets of genes, and researchers compare specific genomes belonging to people suffering from addiction and those without addictive tendencies. They can then identify the presence of certain genes that seem connected with addictive or compulsive behaviors. They further refine their identification of these genes by comparing different people – for example, family members – who display greater or lesser addictive habits.
In recent years, scientists have identified genes linked to smoking and drinking. Further, they have found that these genes seem overrepresented in some neurons – the brain cells that tell other cells to send messages throughout the central nervous system. It could be that these messages are influencing the actions of an individual with regard to using an addictive substance.
Interestingly, these genes that seem related to alcohol and nicotine use are associated with other addictive substances too, such as drugs or medications. This might point to the fact that there are genes responsible for addictions in general. But whatever the evidence may look like on the surface, it is very difficult to reach a definite conclusion. This is because so far it has been impossible to “catch genes red-handed” as it were, that is, to observe them at work doing something that clearly triggers addictive behavior.
Genes express themselves by “coding” the creation of proteins, and these perform a function in the body, but the genes linked to addiction do not. As a result, there is no tangible, observable process that can be studied to see how it might cause addictive habits.
Genetic Influence and Age
A study published by the National Library of Medicine describes addictions as “moderately to highly heritable.” The more closely an individual is related to an addicted family member, the higher the risk they incur of going down the same path. But, it appears that both environmental (external) factors and genes work jointly to affect a person’s relationship to addictive substances. Also, they seem to play a role both in how people begin using one or more substances, and in how – or if – they then transition into addiction.
When looking at substances such as nicotine, alcohol, or cannabis, research shows that in early adolescence, their use is largely influenced by external input. The ease with which young people pick up new habits, good or bad, seems to outweigh any potential genetic interference. Discarding habits is also, for the most part, easier for teenagers and young adults.
As people age, adopting new habits is less likely, and “unlearning” bad habits becomes more difficult. Neuroplasticity – the ability to create new neural pathways in the brain, and therefore acquire the behaviors these pathways govern – decreases. Addictive behaviors in middle-age are far less likely to be learned. The probability that they are influenced by genes rather than conditioning increases.
Addiction – a Complex Issue
Addiction is one example of a trait which may be said to “run in the family”. This points to the fact that addiction – often to an identical, given substance, such as alcohol – seems, in some cases, to be handed down from one generation to the next. Every individual inherits different combinations of genes, and it is the totality of each unique combination that defines a person.
As research on genomes shows, there is no single gene associated with addiction; rather there are whole groups of them. Furthermore, the common consensus is that genetic predisposition accounts only for about half of the risk of developing an addiction, in subjects presenting those genes.
How Can Genetic Studies Help Treat Addiction?
At this stage, no specific medication or therapeutic modality has yet been developed to treat addiction based on what genes tell us. However, one thing which uncovering the origins of addictions does, is to help destigmatize substance use disorders in general. Addiction is seen as partly the result of some innate programming, rather than a conscious choice and a lack of willpower. As a result, there is less shame in the condition or discrimination around it.
As mentioned above, epigenetics explains how external factors can influence how genes work. Research is ongoing into what medications or actions could act upon addiction genes. By modulating the effects of these genes so that they no longer contribute to addictive behaviors, scientists could potentially unlock the key to life-changing addiction treatment techniques.
So, are genes really associated with addiction? To some extent, yes. But inherited genes do not condemn an individual to suffer the same addictions as their relatives. Nor is it a foregone conclusion that people who struggle with addiction will pass this burden onto their children. The encouraging news is that people still have a predominant say in their lifestyle and behavioral choices.