model has good evidence in its favour and is likely to become more dominant as the neuroscience of addiction is further examined.
As can be seen, each of these models is based on a different view and may have a different contribution to make. Each model is likely to have some truths relevant to the addiction problem. However, it is of no use to cling mindlessly to one particular model and totally disregard the others. Such tunnel vision is only likely to cause more problems. Much heartache can be avoided if everyone keeps an open mind and remains tolerant of the views of others in order to avoid unnecessary confrontations with patients, families or healthcare professionals.
It is imperative that healthcare professionals and the public become aware of the different models of addiction. We should also all remain flexible in our thinking in order to use the advantages of the different theories so that we can help substance abusers and their families optimally. We need to work collaboratively in order to assist substance abusers and their families where we can. This would have to include a medical, psychological, social and spiritual approach. Such interdisciplinary collaboration is known as a “biopsychosociospiritual” approach.
It has to be recognised, however, that certain healthcare professionals and certain models predominate in particular phases of treatment. It is clearly important that the emergency treatment and detoxification phase be medically supervised. Similarly, the process of rehabilitation certainly requires a psychologist and social worker. In a routine, non-urgent setting the process of assessment, preparation for change and aftercare should be multidisciplinary. A spiritual component can provide motivation and guidance throughout the entire treatment period. While certain practitioners and thus models may claim dominance in some treatment phases and settings, the overall treatment approach should be collaborative and based on a team effort with a substance abuser and their family at the centre.
The best ultimate outcome for a substance abuser’s recovery and their family’s wellbeing is achieved when a substance abuser is engaged as regularly as possible, using numerous different treatment methods, from various backgrounds. Such multiple contacts should be incorporated into a tailor-made recovery plan for each individual.
CHAPTER 3
THE NEUROBIOLOGY OF ADDICTION
Historically, society believed that substance-related problems were associated with “moral degenerates” and “social misfits”. More recently, however, advances in technology and research have identified much of the neuroscience behind the addiction process. These findings suggest that drug use and drug dependence are neurobiological processes within the brain itself, rather than simply “bad people” making “bad choices”. Such research has contributed to the development of the “disease model of addiction” hypothesis. This evidence leaves no doubt that addiction can be classified as a brain disease, similar in many ways to Parkinson’s disease or even other chronic illnesses like diabetes mellitus and high blood pressure.
The past decade or two have provided us with a more coherent understanding of the addiction process. Researchers are also able to identify the neurological centre responsible for pleasure and reward. This brain centre is critical when it comes to the pleasurable experiences associated with drug and alcohol abuse. Any understanding of drug and alcohol use and abuse has to start with a basic understanding of the neuroscience behind pleasure and reward. Knowing what goes on in the brain helps us to understand why people use, abuse and become dependent on drugs. We may even come to appreciate why people use a drug in larger amounts and over a longer time than was intended, why any attempt to reduce or control drug use is difficult, why so much time, effort and money is spent to obtain drugs, why important activities are neglected and why drug users continue using the substance despite knowing that it may be causing physical and psychological problems.
Our brain is made up of different cells. In fact, there are four different types of brain cells. These are neurons (nerve cells), astrocytes, oligodendrocytes and ependymal cells. Each cell type has a different function. We are primarily interested in the neurons, which are responsible for the transmission of nerve impulses throughout the body and brain and hence for the communication function of the brain. Neurons use electrical and chemical impulses to communicate signals from one part of the brain or body to another. The vast amount of communication that happens throughout our body every second has necessitated the formation of certain larger neuron pathways in order to facilitate easier signal transmission across different parts of the brain and nervous system.
In order to communicate effectively the body makes use of many different chemical substances, all with different functions. The most common chemical neurotransmitters in the brain are dopamine, serotonin, noradrenalin, glutamate, GABA (gamma-aminobutyric acid) and acetylcholine, among many others. Each of these chemical neurotransmitters is used by a particular type of cell; dopamine by dopaminergic neurons and serotonin by serotonergic neurons, for example. It therefore follows that we have not only dopaminergic cells, but also dopaminergic pathways where the majority of dopaminergic cells cluster together to facilitate dopaminergic communication throughout the brain and nervous system. Of course, there are also serotonergic, glutaminergic and many other chemical pathways, too.
When we study pleasure and reward scientifically we are primarily interested in dopamine. Recent research indicates that dopamine is the primary neurotransmitter responsible for pleasurable and rewarding experiences. Dopaminergic neurons and pathways are clearly also of importance in the neurobiology of pleasure and reward (and also addiction and dependence). All neurotransmitter pathways start at some point in the brain and end at another point within the nervous system. In between they pass through relay stations which are called nuclei. Each nucleus has a different name and function. (The system can be compared to a railway line starting in Cape Town and ending in Pretoria, with numerous train stations in between.)
Initially, researchers identified four different dopaminergic pathways spread throughout the brain. These were:
1 The nigrostriatal dopaminergic pathway which starts in the substantia nigra and projects to the striatum.
2 The mesolimbic dopaminergic pathway which starts in the ventral tegmental area (VTA) and projects to the nucleus accumbens.
3 The mesocortical dopaminergic pathway which starts in the ventral tegmental area and projects to the prefrontal cortex.
4 The tuberoinfundibular dopaminergic pathway which starts from the hypothalamus and projects to the anterior pituitary gland.
More recently two more dopaminergic pathways have been identified. These are:
1 The thalamic dopaminergic pathway.
2 The insertohypothalamic pathway.
Of these six pathways it is the mesolimbic pathway that has been associated with pleasure, motivation and reward. It is for this reason that the mesolimbic pathway has also been implicated in addictive behaviour.
The mesolimbic pathway starts in the ventral tegmental area (VTA) of the brain stem. This is a very deep-seated and early brain structure. From the VTA the pathway projects to the nucleus accumbens in the ventral striatum, which is part of the limbic lobe of the brain (also a deep-seated, primitive, early brain structure). When dopamine is released in the nucleus accumbens, pleasurable sensations are experienced. This pathway has therefore been called the “pleasure pathway” of the brain. Stimulating it will release dopamine and make us feel good, happy and rewarded. It may also make us want to repeat the behaviour in order to re-experience such pleasurable feelings.
In our natural world such normally occurring pleasurable experiences include eating a tasty meal, drinking a good wine, sexual activity, winning a race, receiving praise and recognition, as well as listening to beautiful
