Picture of a man smoking a cigarette

Cycle of addiction

The concept of reward is critical to understanding addiction

Eating and taking part in sexual activity are essential for life and for species survival, so are rewarded with a good feeling produced in the brain. Repeating the tasks leads to a cycle of reward.

Dopamine, a feel-good chemical messenger (neurotransmitter), is central to this cycle. Alcohol, nicotine and drugs such as cocaine and heroin all increase dopamine levels.

But why do some substances just produce pleasure while others are addictive? The likely answer is that in addiction substances trigger permanent changes to the dopamine–reward pathways, which lead to cravings. In effect, drug intake goes from being a voluntary activity, under conscious control, to an unconsciously driven desire, with different brain areas taking over. Pinpointing exactly how each substance works can help identify ways to block the addiction cycle.

Lead image:

Dana Le/Flickr CC BY

Further reading

About this resource

This resource was first published in ‘Thinking’ in September 2006 and reviewed and updated in August 2014.

Neuroscience, Psychology
Education levels:
16–19, Continuing professional development