More than ‘70,000 people died from drug overdoses in 2017, making it a leading cause of injury-related death in the US. Sixty-eight percent of those deaths involved a either a prescribed or illicit opioid’1.
Opioid Addiction presents itself as an epidemic, particularly in the United States of America, coming under the clinical terms Opioid Dependence and Opioid Use Disorder. Unfortunately, we witness pain relief (analgesia) take a toll on the mind and body, developing into dysphoria and addiction. It is a great interest of mine to understand how a clinical method of pain relief causes, on average, 130 Americans to die every day.
Let us explore the foundations of drug addiction. The innate reward and pain suppression systems are heavily involved in our natural tendencies to carry out certain actions, majorly because dopamine (a catecholamine which acts both as an excitatory neurotransmitter and hormone) is released as a part of these systems. The Mesolimbic System is a subcategory of innate reward, commonly named “the reward pathway”.
Reward pathways are the reason we feel pleasure when engaging in various activities; a key drive in the evolution of the reward pathway is the notion that it subconsciously motivates behaviour that increases the chance of our survival; hence why we feel replenished from drinking water and feel pleasure during sexual intercourse- an incentive to produce genetically diverse offspring which is beneficial to the survival of the population.
In this example, we will explore the brain’s dopaminergic response to eating one of the nation’s most beloved meals – Nando’s chicken and peri-peri salted chips.
The Mesolimbic pathway2 consists of five regions of the brain: first, the Ventral Tegmental Area. The VTA is a complex midbrain region, being mainly composed of dopaminergic neurones. In response to stimuli such as such as eating succulent Nando’s chicken, dopamine is released and projected to several cortical and limbic structures in the brain.
Next in line is the Amygdala, which deals with our emotional responses. During the excitation of the Amygdala due to dopaminergic projection via the VTA, you are informed you that you have enjoyed the full-flavoured sensation of eating peri-peri salted chips.
The Nucleus Accumbens deals with motivation, decision making and controls motor responses, it is essentially the ‘pleasure centre’ of the brain. In this case it motivates us to take another bite of our ½ chicken, therefore exciting the reward circuit once more.
The Hippocampus functions as a storage of memory, linking our memories to sensations. It stores the place, time, and specific type of sensation in your short term and (depending on the potency of the stimuli) long term memory.
Finally, dopaminergic release to The Prefrontal Cortex, which deals with cognition and creativity, allows you to focus on the stimulus and diverts some of your attention to the flame-grilled, flavoursome dish.
These regions of the pathway collectively assort importance to environmental stimuli by associating them with reward and sensation. Unfortunately, when Nando’s chicken is replaced with an excessive use of Fentanyl, Oxycodone and Heroine etc., the pathway is overstimulated, and unnatural dopamine levels are produced in the brain. The responses of the five Mesolimbic regions are all intensified with the initial use of opioids.
Prolonged use of opioids results in the brain being trained to find ways to repeat this stimulating pathway again and again. Ultimately leading to desensitisation of receptors in the five regions3, this is what formulates the condition of ‘tolerance’ as your response to the same dose of opioids deteriorates over time, requiring higher and higher doses to feel the same salient response. Not using opioids at all after these effects can lead to physiological imbalance between the body’s homeostatic responses and the depressant nature of opioid drugs like heroin – this imbalance is referred to as “withdrawal symptoms” which can result in anxiety, shivering and tremors.
I consider addiction to be primarily a biological process and not simply a result of failed willpower or mental strength, people become victims to opioids as we witness legitimate pain prescription turn into heroine addiction and illicit abuse4. Our motivational and emotional lives are shaped by underlying neurophysiological processes. These neuroplastic changes are unique due to genetic and environmental factors which may influence our vulnerability to addiction and other diseases. The components of addiction complicate one’s ability to come out of such a dependant state.
To conclude, there must be a re-evaluation of the clinical use of opioids and their long-term administration. If we can balance the dynamics between opioid and non-opioid chronic pain medications such as Tylenol, Motrin and NSAIDs we can offer patients maximal chronic pain management with minimal risk of opioid dependence.
For those already suffering from Opioid Use Disorder, we can do our best to combat this with love, cognitive behavioural therapy, rehabilitation and moral support from family and friends – these are all collaborative factors which help patients re-enter stability.
- NCDAS. (2019).  Opioid Crisis: Facts & Statistics on Prescription Opioid Addiction. [online] Available at: https://drugabusestatistics.org/opioid-epidemic/.[Accessed 15 Jul. 2020].
- Mayfieldclinic.com. (2018). Anatomy of the human brain. [online] Available at: https://mayfieldclinic.com/pe-anatbrain.htm.[Accessed 18 Jul. 2020].
- Harvard Online Courses. (2016). The Opioid Crisis in America. [online] Available at: https://online-learning.harvard.edu/course/opioid-crisis-america [Accessed 18 Jul. 2020].
- Painkiller.vice.com. (n.d.). Painkiller: America’s Fentanyl Crisis. [online] Available at: https://painkiller.vice.com/p/1.