Addiction causes – Genetic variability related to attention, impulsivity, and drug use.

It will probably come as no surprise to at least most of you that addiction is closely linked to problems of self-regulation (like ADD and ADHD). This is one of the main reasons that professionals view addiction as a disease, and not a choice.

This post is pretty advanced, but it should leave you knowing a lot more about the relationship between attention, self-regulation, impulsivity, and addiction. Also, when I use the term “Addiction causes” I have to stress that the link to date has been one of association, NOT causation. We don’t truly know what causes addiction.

What is self-regulation?

Self-regulation is the ability to control one’s actions in ways that are appropriate to specific situations. Having to do with the most advanced aspects of cognition, self-regulation is considered to be the prime example of human executive functioning. It’s this aspect of thought and brain function that is thought to truly separate humans from other animals.

Being this important for our functioning, you can probably imagine how complex and interactive the brain systems that control executive functioning are. You’d be right.

These systems, centered in the Prefrontal Cortex (PFC), the part of the brain nestled right behind your forehead, are connected to essentially every other brain system, including vision, hearing, motor control, emotion, etc. It’s the PFC that controls these systems and tells the brain what brain impulses should actually be acted on.

And impulses is a great word for it. Given how complex the system is, there are many things that can affect its function. There are genetic factors, some that have to do with early development, and others that are affected by behavior, including the ingestion of drugs.

In this post, I would like to focus on the genetic influences, later on, I’ll talk about the developmental influences and the effects of drugs and other behavior on these systems.

Genetic influences on executive function:

There are a host of genes that affect different aspects of executive function. Some of these, like those impacting genes related to DAT, DRD4, and COMT functioning, have an effect on dopamine function that has been correlated with personality traits like sensation seeking and impulsivity.

Hyperactivity

As I’d mentioned earlier, these personality traits themselves, and the genes that affect them, have been found to be associated with addiction as well as several other conditions and syndromes that are related (such as ADD and ADHD).

Just to be clear, we all have these genes, but there are different version of them (called alleles). Some of these versions are more common than others, and some are associated with the conditions I mentioned earlier.

For instance: There are 2 versions of the COMT gene. This gene codes for a chemical in the brain that breaks down DA (this breakdown is important for brain function as I’d mentioned in an earlier post). One of these versions (named MET) breaks dopamine more slowly while the other (VAL) breaks it down quickly. The VAL allele actually breaks the dopamine down so fast that it interferes with dopamine’s ability to properly get its message across. That’s why this allele has been linked to attention and impulsivity issues. Each of these alleles has a 50% prevalence in society, which means that 1 out of 2 people have the VAL allele. Obviously its effect is not enormous, but along with many other factors, it has a significant impact on dopamine functioning.

Similar issues come up with one of the versions of the DRD4 gene, which codes for a specific type of dopamine receptor; and with the DAT gene, which codes for the DAT transporter I talked about in the cocaine post mentioned earlier.

Again, while the effects of each of these genetic variants is small, these can add up along with other genetic influences and environmental factors (especially during early development) to overall affect a person’s ability to control impulses.

Obviously, those who have a more difficult time controlling their impulses would have a more difficult time making appropriate choices. These difficulties can lead some to be more likely to start behaviors that are detrimental, including the use of drugs. The drugs themselves can then further exacerbate the problem (as we’ll see in a future post), and can do other things to make users more likely to keep using them.

In short, while genes don’t make people use drugs, they can definitely make it more likely for certain people to engage in risky behavior, including trying drugs in the first place…

Question of the day:
Did any of the people you know who have developed drug use/abuse problem show problems with impulsivity before their drug use?

4 Replies to “Addiction causes – Genetic variability related to attention, impulsivity, and drug use.”

  1. I wonder if some of this has to do with homeostasis problems. Usually homeostasis is fine tuned, for example your heart rate and breath gradually increase as exertion increases. Perhaps with addiction, impulsivity and attention people have problems where a gradual homeostasis regulating this system somehow get’s changed to a bistable switch that is either on or off.

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