The science of addiction – why it’s all about the brain

Addiction can come in many forms, from substance abuse of things like alcohol, sugar and nicotine, to behavioural problems with gambling, shopping or working out.

The important thing about all addictions however, is that they begin in the brain. While our bodies may become dependent on certain substances with physical addictions, behavioural addictions start in the same place, and are usually to do with our pleasure response. Senior lecturer in Psychology at the University of Gloucestershire Josie Trustcott, explains how we repeat behaviours that then turn into addictions.

Our brain registers all pleasures in the same way; be that from a psychoactive drug, a satisfying meal or a monetary reward. Whenever we feel pleasure, our brain releases the neurotransmitter dopamine into the nucleus accumbens, a region referred to as the brain’s pleasure centre.

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Consistently getting this release of dopamine from a substance or behaviour often leads to addiction – we know doing this feels good, and crave that rush so re-enact the behaviour again and again.

This happens as part of our brain’s system of reward-related learning. The reward circuit in the brain is an area also associated with memory and motivation, which further drives us to continue that behaviour.

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Substances such as psychoactive drugs greatly increase the amount and intensity of dopamine released, which greatly increases the chance of addiction.

Over time however, this constant overloading of the brain’s reward centre causes it to not react to dopamine in the same way – and addicted people often find they no longer receive the same amount of pleasure from a substance or behaviour they once did.

This results in them needing to take more/ repeat the behaviour more often to get the same sort of high.

The brain also records environmental cues surrounding an addiction – so a heroin addict may feel intense craving if they see a hypodermic needle. This consequently makes it very difficult for recovering addicts, as even little visual cues can spark the intense conditioned craving their brain has learned.

So there you have it – the science of how we become addicted.

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