Morning Coffee Science

Drug addiction - not a choice


Drug addiction is a commonly misunderstood illness. Most people do not see drug addiction as something of an illness, but rather as a failure of one's moral character. "It is your choice"; "you made a poor decision"; "Just say NO" - say proponents of this position (the most famous, of course, being the former US first lady, Nancy Reagan). Society treats drug addicts as weak-willed individuals rather than chronically ill people and that has to change. This is not a view that science of addiction currently holds. This article will attempt to explain why drug addiction profoundly alters our brains and hinders our ability to make rational choices. Drug addiction is not a choice.

In the 1930s, when researchers first began investigating addictive behaviors, they came to believe that addicts lacked willpower. A potential way to overcome this lack of willpower was through punishment which should have encouraged the addicts to muster their will and break the habit. It is not hard to see why they would have thought that way back in the day - (a) they did not have necessary imaging techniques (e.g. fMRI) to delve into the brains of their patients, (b) animal model research was not yet recognized as having the potential to probe the neurobiology of addiction, (c) society was much more conservative with regards to how it treated misdemeanours associated with addiction (e.g. stealing, lying, cheating).

The scientific consensus has profoundly changed since then. Nowadays, we recognize that addiction changes both the structure and the function of the brain. According to this view, addiction is analogous to diabetes or cardiovascular diseases. Just as diabetes impairs the pancreas and cardiovascular diseases damage the heart, addiction interferes with the "normal life" of our brains. Drug addiction (also called substance use disorder (SUD)) is a compulsive physiological and/or psychological need for a habit-forming substance such as alcohol, tobacco, or cocaine. If one is not able to get their drug of choice the patient goes into withdrawal - a state characterized by intense craving and various negative effects that can even lead to the death of the addict. Most people are not able to kick their drug habit without utilizing multiple strategies that are out there - psychotherapy, medication, self-care, etc.

Drug addiction is a highly heritable trait. In order to prove the latter fact in humans, scientists use twin and adoption studies. The idea here is to take two twins who, by default, are genetically very similar and put them into different households - if the twins still end up having problems with drugs (e.g. alcohol), susceptibility to drug addiction has a very strong genetic component to it. If the twins end up not being drug addicts, scientists conclude that genetics are not that important and the environment has a greater effect on drug addiction. These twin and adoption studies show that 40% to 60% of susceptibility to addiction is hereditary. This means that certain individuals have a greater propensity to be addicted by the virtue of who their parents are.

So what happens to the brain of a person who is addicted? The first thing is that it makes the person feel a pleasant high. A key biochemical molecule to understand here is dopamine. Dopamine's main roles are controlling voluntary movement and emotional responses. For the sake of this blog post, the reader can think of dopamine as a biochemical molecule that makes a person feel good. If a person has more of this molecule than usual in their brain, they will feel ecstatic.

A key brain structure where dopamine is released is the limbic system. The limbic system is the brain's reward center. The limbic system is made out of different sub-structures - namely, nucleus accumbens, amygdala, and hippocampus (see picture below). Dopamine is released in the brain structure called nucleus accumbens as it contains a lot of dopamine secreting neurons. So, when a drug addict takes a drug, their nucleus accumbens is flooded with dopamine. A pleasurable drug-induced high follows.

The second thing that happens to a person's brain is that they learn that the drugs make them feel good. Dopamine interacts with another "brain chemical" called glutamate to take over the brain's system of reward-related learning. This system is "originally" for linking crucial for survival human behaviors to pleasure and reward. For example, eating or mating is associated with pleasure so as to incentivize a human to continue doing these. Addictive substances hijack this circuitry. A drug becomes seen as "necessary" for survival and a human starts to crave drugs because of it. A crucial role here plays the hippocampus and amygdala structures as they lay down the memories of this rapid sense of satisfaction from a drug and condition a drug-seeking response respectively (look for the picture about brain reward center).


Why is it important that drug addiction is not a choice? Apart from promising novel therapeutic interventions that could help people stop drugs easier, there is a question of public health policy. The philosophy underpinning the current dominant drug policy around the world is that of "war on drugs". The idea here is that persecution of the supply chain in third world countries, local drug dealers and local drugs addicts will stop the drug epidemic. However, this policy is ineffective in preventing drug-related activity.

Why? Well, it is informed by societal moral panic as opposed to science. Drug addicts should be approached in a way that engages them in a process of rehabilitation and mitigation of risk. Our society should not be treating individuals who are chronically ill as vile criminals. Just as we tolerate someone who has fallen out of the workforce for a broken foot, we should also try to help someone who is addicted to drugs to get better. Portugal is one of the countries that understand this. Portugal decriminalized all drugs in 2001. This means that they won't prosecute drug users, but will still not allow drugs to be illicitly manufactured and supplied. They have set-up safe injection sites to mitigate the harms of overdose. The rates of people engaging in drug-related activity decreased as decriminalization decreased the stigma of seeking professional help to quit. The rates of overdose went from the highest in 2001 in the EU to one of the lowest in 2012. Drug addiction is not a choice and if we listen to neuroscientists then we will be able to decrease human suffering from drug-addiction through science-guided public drug policy.

Watch a video about the neurobiological basis of addiction.

The article was prepared by Matas Vitkausas on behalf of INA


Sources:…/how-addiction-hijacks-the-brain neurons of the midbrain,the mammalian central nervous system.&text=Dopaminergic neurons are found in,and a high iron content. decriminalised the personal possession,as fines or community service Image sources:…/how-addiction-hijacks-the-brain decriminalised the personal possession,as fines or community service