The Dopamine Paradox - Unravelling the Neurobiology of Addiction

Posted Saturday, 15 June 2024

The way we view addiction across the world is beginning to change…and about time! Here at Horizon, we dream of the day when addiction isn’t seen as a character flaw or a moral failing, but as an illness; a disease that deserves our compassion and empathy. To that end, it seems fitting that we explore exactly what happens to the brain of an addict as the disease progresses, and what we can do to change it. In this article, we will discuss the relationship between Dopamine and its receptors, how this relationship remodels the structure of an addict’s brain at the cellular level, and how remission can reverse those changes.

Dopamine: The Pleasure Molecule

Joy, Fear, Alertness, and Pleasure; these intangible concepts are produced in our minds by brain chemicals called neurotransmitters. It’s worth mentioning here that the neurobiology of addiction is multi-faceted, and involves a multitude of different signalling pathways and neurotransmitters. For this article, we will focus solely on Dopamine, which is responsible for reward, pleasure and motivation. When we do things that our brain considers productive or survival-enabling (eating sugar-rich foods, exercising, sex, social interaction), it rewards us by releasing Dopamine. The effects of this are two-fold: 

  • Firstly, it boosts our mood and makes us feel like we’re on top of the world. If you’ve ever hit a new personal best at the gym, or replayed your favourite artist’s latest album for the umpteenth time, then you are already intimately familiar with Dopamine and its magical properties.

  • Secondly, it re-traces the pathways in the brain that preempted the rewarding activity and reinforces them. These pathways become easier to trigger and therefore make the activity more likely to occur in the future. 

So, Dopamine tells us that an activity is good, and incentivises us to do it again, whilst making it easier for us to do so. 

The Dopamine-Dopamine Receptor Relationship

Dopamine communicates by binding to receptors on our nerve cells, which triggers those cells to respond. The strength of that response is dependent on the number of receptors, how sensitive those receptors are, and the quantity of Dopamine released. A Dopaminergic system full of Dopamine, with abundant, sensitive receptors could reasonably be compared to a blazing supernova (in neurobiological terms). This is somewhat counterproductive to a healthy life, so our brains go to great lengths to balance these three factors over time. 

Changes in the Dopaminergic System During Addiction

There does appear to be a novelty effect, whereby new activities trigger a more powerful release, but in an ideal brain, the effects of Dopamine should be proportional to the productivity of the activity. 

What happens when this isn’t the case though? 

Drugs - alcohol, cocaine, methamphetamines and opiates, to name a few - stimulate far greater releases of Dopamine than they should. Moreover, they actually increase the sensitivity of Dopamine receptors in the short term, to further augment their euphoric effects. Not all drug euphorias are created equal; some have a greater propensity for abuse and addiction than others. Normal activities that trigger the release of Dopamine struggle to compete. The same can be said of addictive behaviours, prominent examples being gambling, sex, and video games. The brain diligently documents these experiences, making sure you never forget just how great the moment felt - the technical term for this is salience. 

In isolation, these experiences do not make an addict. Opiates are commonly prescribed for pain in medical contexts, but most people return home and never use them again. For an addiction to form, repeated exposure is required. Over time, the brain notices that its Dopaminergic system has been overactive; in response, it reduces the number of Dopamine receptors present and scales down its natural Dopamine production. What this means in practice is that larger amounts of the substance/behaviour (and therefore higher and higher quantities of Dopamine) are required to achieve the same response - this is referred to as tolerance. The bar for reward rises, and any activity that can’t meet this threshold feels sub-optimal, leaving addicts with fewer and fewer options to feel the same level of pleasure or satisfaction. 

Comparison of Dopamine receptor levels in the brains of healthy control subjects vs drug abusers. Red represents a high level of receptors.

The result? 

A perpetuating cycle of escalating substance abuse. An increasing reliance on the behaviour to experience any sense of reward or fulfilment, to the point where we feel incomplete without it. New users often seek to feel good, but older users tend to rely on substances or behaviours to avoid the lows associated with dopamine deficiency - this is one of the mechanisms behind withdrawal.

Most people are exposed to one or some of these substances/behaviours during their lifetime, so it’s unclear why the brains of addicts are more susceptible to the changes discussed above. The prevailing consensus is that genetic, environmental and neurobiological factors interact to heighten the risk in some individuals. Addiction can affect anyone, but research suggests that the following groups carry a greater burden of disease:

  • People with other mental health disorders (depression, anxiety, ADHD)

  • Trauma survivors (military veterans, victims of abuse)

  • Adolescents and young adults

  • People with chronic pain

  • Socially and economically disadvantaged groups

Neuroplasticity and Addiction

Put simply, neuroplasticity is the ability of our brains to form new connections between neurons. New experiences are coded into our minds as new connections, which extend the pathways that are already present. We've discussed how Dopamine can not only stimulate the formation of neural pathways but also enhance their strength, all the while amplifying the salience of a particular event. In addicts, the pathways that lead to consumption become stronger, at the expense of pathways that deal with decision-making and impulse inhibition. Our processes for rationality become physiologically and psychologically compromised, in the face of an overwhelming emotional craving.

Reversal of Dopamine Dysregulation During Remission

For the uninitiated, remission refers to a period of abstinence from the addictive substance or behaviour. Earlier in the article we mentioned how the brain strives for Dopaminergic equilibrium. Addiction corrupts this process to create addicts, but remission can utilise the same process to induce recovery. Dopamine deficiency, if left untouched, will prompt the brain to increase the number of receptors back to baseline and increase Dopamine production in tandem. The timeline for this process is highly variable, depending on the baseline of the individual, the substance in question, the age of first use and the time spent engaging in the activity prior to abstinence. Replacing the old habits with healthier alternatives that increase Dopamine production naturally can also significantly improve the recovery time, some of which have been listed below:

  • Exercise: Physical activity, particularly aerobic exercise, has been shown to increase dopamine levels in the brain. Activities such as running, cycling, or dancing can trigger the release of dopamine, leading to feelings of pleasure and reward.

  • Listening to Music: Enjoying music that you love can also lead to dopamine release in the brain. The anticipation of a favourite song, coupled with the emotional response to the music, can stimulate the dopamine system and enhance mood.

  • Engaging in Creative Activities: Activities that involve creativity, such as painting, writing, or playing a musical instrument, can activate the dopamine system. The process of creating something new and rewarding can lead to dopamine release and feelings of satisfaction.

  • Socialising: Positive social interactions, such as spending time with friends, family, or loved ones, can boost dopamine levels in the brain. Engaging in meaningful conversations, laughter, and shared experiences can all contribute to the release of dopamine and feelings of connection and pleasure.

  • Setting and Achieving Goals: Setting and accomplishing goals, whether they are small daily tasks or long-term aspirations, can activate the dopamine system. The sense of accomplishment and progress that comes from reaching a goal can lead to dopamine release and motivate further goal-directed behaviour.

The last habit is crucial, and perhaps the most difficult. Addiction hijacks the motivation system in our brains, so actively working to reclaim it is an essential part of recovery.

Next steps

Understanding addiction as a neurobiological phenomenon sheds light on its complexities and offers a pathway to recovery. The Dopamine paradox, central to addiction, speaks to the interplay between Dopamine's rewarding effects and the brain's adaptations to chronic exposure. Over time, repeated exposure leads to tolerance, as the brain adjusts by reducing Dopamine receptors. This results in a downward spiral of escalating substance use or addictive behaviours.

That spiral is bidirectional - remission offers hope for recovery by leveraging the brain's neuroplasticity. Through abstinence and healthy habits like exercise, socialising, and goal-setting, individuals can restore Dopamine equilibrium and rebuild their lives. While recovery may be challenging, it is achievable with support and understanding.

Here at Horizon Rehab Center, we pride ourselves on providing a comprehensive package of care for those looking to stay sober.

You don’t have to suffer alone - get in touch to kickstart your journey!