The rationality of consuming addictive substances

The general public is vastly misinformed when it comes to mental health, particularly when it comes to substance abuse and addiction. The definition has recently been updated to be defined as a brain disorder, where the brain’s reward system is distorted by repeated consumption of certain addictive substances.[1] However, unlike popular belief, not everyone is equally vulnerable to addiction and depending on genetic and environmental factors, most casual drug users can stay as casual users.[2] For most consumers of alcohol and other drugs (AOD) who are addicted, we see normal reactions to drivers of demand such as price, availability and quality of drug. The difference for addicted consumers is not that they become ‘mindless zombies’ but is that they gain greater utility from consumption of AODs than other consumers, due to their brain’s altered reward system, and are willing to incur higher costs. Although it would be difficult to say that this is completely rational behaviour, there is clearly still some sort of rationality behind drug consumption.


Why do people take drugs? (i.e. what affects demand for drugs)

Let’s start with one simple fact. Drugs yield positive utility. No one would take drugs if they didn’t make you feel good. Keeping this in mind, what are the key drivers of demand for AODs?


Different drugs can have very different effects. For example, people might use stimulants such as ecstasy to boost their energy when going clubbing but turn to alcohol or marijuana to relax after work. This means we cannot treat all drugs as if they are in one market; there is little evidence to suggest that a frequent cannabis user will ‘graduate’ to different drugs such as heroin.[3]

It should also be noted that the effect a drug has changes over time. Individuals who consume a substance regularly become used to it and eventually need higher doses to achieve the same ‘high’.[4]


As with all goods and services, price is a major determinant of demand. The lower the price, the more people it will appeal to. If the price of an individual’s preferred drug rises too much, they are likely to substitute for a cheaper alternative.[5]


This refers to both to the legal status of a drug and the social acceptability. A drug which is socially acceptable, legal and widespread such as alcohol is much more likely to be consumed (85.5%) than an illegal drug which is socially shunned such as crystal meth (1.4%).[6]

Note that all of these would be very rational considerations in the goods and services market for any other product.


Addiction as a substitute for connection

The public’s notion of the biological addictiveness of drugs started through a famous ad aired by Drug-Free America. In this experiment, a rat is placed alone in a cage with two water bottles. One has water and the other is laced with cocaine. Almost every time the rat becomes obsessed with the drugged water, drinking copious amounts until it dies from overdose.

However, in the 1970s Professor Bruce Alexander noticed the experiment was strange. The rat lives alone and has nothing to do apart from take the drug. He devised a similar experiment but instead of an isolated cage, he built Rat Park, a cage with good food and lots of rat friends to socialise with. The rats still tried both bottles, but they didn’t like the drugged water, consuming only a quarter of the drugs that the isolated rats did with none of them dying from overdose.[7]

A similar result can be seen in the human equivalent of this experiment. During the Vietnam War, heroin consumption became extremely prevalent amongst soldiers with about 20 per cent becoming addicted. People waiting back home were terrified that a huge number of addicts would be returning home when the war ended. However, upon returning to their homes, about 95% of the addicted soldiers just stopped – no rehab.[8] This is significant as it suggests that environment (both physical and social) is a key factor to changing behaviour. As succinctly put by, “the opposite of addiction isn’t sobriety, it’s connection”.[9] In economic terms, addictive substances act as a substitute good for healthy human connections.

Although addiction unquestionably has a biological element to it, there is an increasing pool of evidence suggesting that a huge part of addiction is to do with social connection. Humans are intrinsically social creatures. When people cannot form healthy connections, they substitute them with unhealthy ones, with shopping, gambling, alcohol and other drugs. Substance abuse can be incredibly damaging, both for the individual experiencing it and those close to them. However, it is important that as the general public we remember that individuals usually take addictive substances for a reason. Sometimes to alleviate pain, sometimes to distract from harsh circumstances, and when we keep this in mind, it doesn’t seem so irrational after all.



[1] Nestler, EJ (2013). Cellular basis of memory for addiction. Dialogues Clin. Neurosci. 15(4): 431-443.

[2] Addiction Science Research & Education Center

[3] Jadidi, N., & Nakhaee, N. (2014). Etiology of Drug Abuse: A Narrative Analysis. Journal of addiction.

[4] NIDA (2007, January 2). The Neurobiology of Drug Addiction. Retrieved from on August 10 2018

[5] Nauert, R. (2015). Alcohol & many medications make a risky mix. Retrieved from: on August 10 2018

[6] Australian Institute of Health and Welfare. (2016). National Drug Strategy Household Survey detailed report 2015. Canberra: AIHW.

[7] Alexander, Bruce K., (2001) “The Myth of Drug-Induced Addiction”, a paper delivered to the Canadian Senate, January 2001, retrieved August 10 2018.

[8] Groth, A. (2012, January 4). This Vietnam Study About Heroin Reveals The Most Important Thing About Kicking Addictions. Business Insider. Retrieved from: on August 9 2018

[9] Hari, J. (2017, April 18). The Likely Cause of Addiction Has Been Discovered and It Is Not What You Think. Huffington Post. Retrieved from: on August 9 2018.