The disease model of addiction emphasises a user’s lack of control, describing addiction as a disease. The source of origin can be:
Addiction impairs the brain much like other medical problems. If it takes hold when the brain is still developing during adolescence, the person is most vulnerable.
The earlier drugs are introduced to the brain, the greater the long-term damage.
The contemporary model of addiction describes addiction as changes to the brain’s mesolimbic pathway.
This also takes into account the biological and sociological concepts relating to the user, forming an all-rounded vision of addiction.
Addiction involves changes to both the brain and the body; chemical changes occur in the brain that isn’t consciously altered but is a direct result of the drug addiction.
It seems obvious that nature and nurture influence the nature and existence of addiction. For example, stress is directly the result of a stressful environment. The same works for addiction.
If you are surrounded by addiction, you are more likely to follow suit in behaviour and actions. Individuals that are surrounded by drugs and alcohol are more likely to engage in that behaviour and experiment with it.
Parental and social influence along with cultural norms contribute to addiction. Unfortunately, some are born into a more ‘user-friendly’ environment, it is then a game of chance whether they become a user too.
If you are born into a using environment and have parents that are users, this is a forgone conclusion that you will most likely use substances. The odds of genetic factors are stacked against you.
Sickle cell anaemia is an inherited red blood cell disorder. Similarly, genetic and mental factors can also heavily contribute to the dangerous cycle of addiction.
The chance that addiction can be genetically attributed stands at around 50%, emphasising the genetic susceptibility of addiction.
Addiction is recognised as a disease that must be monitored, treated, and managed, much akin to other types of diseases. 
The shame and stigma surrounding addiction has much to do with the perception of substance use disorder as weak and immoral. Understanding addiction as a disease is crucial to the refusal of this binary thought.
Addicts struggle with the ability to discontinue use on their own without help, appropriate treatment, or intervention. Like diseases such as diabetes and hypertension, addiction is prone to rates of success and rates of relapse.
Free will, determinism and moral responsibility are all common notions in the sphere of philosophy and ethics.
It stands that if we are free, we are held morally responsible for all actions as they are a choice, made independently by us.
In the context of addiction, the disease model states that addiction is not a choice. Free will compromises this idea, stating that agents have the ability to choose between multiple courses of action.
The same goes for criminals; we have the option to stab someone every time we see them, but we choose not to, because we have the ability to.
However, the brain-disease model of addiction refutes this argument.
In reducing the attribution of free will, it relocates the cause of the disorder to the brain and not the person in question.
This reduces blame in reference to addiction, but what about moral responsibility?
Moral responsibility is the deserving of blame or praise following an act or omission you have made or done. If a user isn’t to blame for taking drugs, are they not to blame for the actions done on drugs?
Whether you think addiction is a choice is your answer to this question.
The disease model of addiction states their answer: addicts do not have a choice, the disease is caused by the brain, and whether it can be treated and managed depends on the severity of the disease.
Many argue that labelling people ‘addicts’ is stigmatising. Keeping them from implementing self-control, the term ‘addict’ carries numerous negative connotations.
This is noted in the principle of harm reduction; reducing stigma and using terms such as ‘addict’ can help a user get the help they need, without the feelings of shame and embarrassment. 
Continuous use and exposure of drugs to the brain desensitises our reward pathways. This affects the feelings of emotion and pleasure, where we become conditioned to expect drugs.
This leads to constant cravings and the ‘need’ for an increase in the amount of substance and quantity of use. This leads directly to withdrawals and negative symptoms.
When using a psychoactive drug, not only does the ceasing of use cause emotional and physical withdrawals, but mental symptoms will occur. These can include decision-making, self-regulation and impulse control.
Drugs bind to receptors in the brain, releasing serotonin and giving rise to feelings of euphoria and increased pleasure.
Once entered into the brain, the addictive substances mean the brain becomes dependant, and less likely to produce its own serotonin and other chemicals.
This reduction in the production of dopamine affects the risk and reward system, leading to physical and psychological addiction.
The more one uses drugs, the harder it will be to break the cycle of addiction and reduce dependency.
According to the disease model of addiction, adequate treatment is possible. Similar to medical diseases, addiction treatment depends on your needs and goals.
What works for some may not work for all, but rehab is largely the most viable option for users.
For example, the different treatments can refer to:
Views regarding addiction and treatment have gone through many stages over different time periods. Drugs are also more readily acceptable in some cultures, more so than others.
Advances in neuroscience have aided our investigation into the brain and the ‘disease’ we label addiction.
This has led to the ultimate recognition that addiction is a chronic brain disorder, which can be helped with the right treatment. 
There are three main stages of addiction that link directly to brain circuits and a change in nature:
These are connected to the aforementioned sources of origin for addiction, such as environment and genetics. These factors increase the likelihood of use and the chance of progressive misuse of substances.
This knowledge and medical advancements have led to improvements in the cause, effect and treatment. Further, it has reduced the stigma of addiction in its disease label.
The disease label suggests that substance addiction and alcohol use disorder is not a moral failing, but a brain disease theory of addiction.
This critical understanding of addiction has enabled more focused treatment of addiction, assessing addictive behaviours and analysing the basis of addiction too.
The biological basis of disease emphasises brain chemistry and the neurobiology of addiction, where stages of the addiction cycle mimic stages of other medical diseases.
Getting rid of addiction stigma and transferring addiction into a disease concept, the notions of addiction remain biological, environmental and genetic.
This leaves behind the generalisations attached to the bad behaviour and historically motivated reasoning.
The disease model of addiction has contributed to a wider understanding of the neurological effects, negative consequences and root causes of addiction, allowing developments for intervention and harm reduction.