Contextualising opioid addiction through science and history.



Opioid overdose deaths are currently the highest on record in the UK and globally.

Mortality, drug use & addiction are intimate, taboo, and difficult to talk about. It is a complex phenomenon that is not fully understood and there are many differing views on why this is the case.

Today, heroin and opioid use as well as related mortality are considered to be a public health crisis. However it was not always so.


Opium Poppy


Heroin and opioids originate from the opium poppy plant which has many properties and has fulfilled societal, religious and cultural functions for thousands of years. Opioids have been used recreationally, medicinally and problematically probably since around 3400 B.C. They can produce intense euphoria, reduce pain as well as dampen the body’s natural drive to breathe. 



Opioid family tree

This tree depicts the vast array of naturally-occurring, semi-synthetic and synthetic opiate products that either derive from, or are emulating, the Opium Poppy. This is where the terms opiates and opioids are distinguished. Opioids refer to the whole family of opioids, endogenous, naturally obtained from the opium poppy, semi-synthetic and synthetic. Opiates usually only refers to drugs that are derived from the opium poppy.


Don't forget to breathe

A regular rhythmic pattern of breathing is a fundamental function of the body. It maintains the correct balance of oxygen and carbon dioxide in the blood. Opioids can alter this rhythmic pattern and disrupt the balance by dampening the body’s drive to breathe. In most cases, this is temporary and the body can rebalance itself. However, in other, fatal cases, the body is unable to regain balance.


Areas representing action of opioid receptors. Scan credit:

Areas representing action of opioid receptors. Scan credit:


Under the skin

Homeostasis is the continual balancing act that the human body performs in order to maintain its functioning. The body does this via central and peripheral systems, interconnected through nerves and blood vessels. The central system consists of the brain and spinal cord. The peripheral system comprises everything outside of the central system. The interconnection is highly complex and is wired throughout the genomic coding found in the cellular and molecular architecture and neural networks that govern our vital bodily functions, sensations and behaviours.

Our bodies also have a naturally-evolved infrastructure, like a power grid, that processes and releases its own naturally-occurring opioids within our systems. These are known as endogenous opioids, e.g. endorphins, enkephalins and dynorphins.

All opioids trigger a response in the body by binding to opioid receptors. These are protein molecules that are located on the surface of certain nerve cells. Opioid receptors are like gatekeepers that are located in various locations of the brain that are implicated in the control of breathing and respiration, euphoria and pain control, amongst other functions. They are also located in peripheral regions such as the intestinal tract, and in areas relating to the breathing signalling system (respiratory feedback loop); for example in the carotid body. The physiological and psychological effects differ depending on the particular opioid and the type of receptor that is activated or inhibited.


Opioid mortality complexity diagram.


Complexity diagram

This complexity diagram is based on the computational artificial neural network model first developed by Warren McCulloch and Walter Pitts in 1943. The input layer passes values onto the hidden layer which in turn passes values onto the output layer. It is a model for neurons and synapses and can be used to make predictions for complex datasets. 

Advances in medical science are such that these artificial neural network models have been applied to a variety of medical problems. For example, they are used to predict mortality and morbidity after heart surgery. 

Prediction of mortality in any given overdose situation is dependent on a number of different risk factors. Although values in this model are lacking, meaning numerical predictions or regression analyses cannot be conducted, it represents the immense complexity of the issue.