When a person uses drugs, it has significant effects on her brain. Recreational drugs, such as opioids, affect neurotransmitters in the brain. For example, the ]]>Canadian Institutes of Health Research and the Canadian Institute of Neurosciences, Mental Health and Addiction]]> explain that when a person uses an opioid, such as heroin, the drug binds to receptors in the brain that endorphins and other opiate-like substances produced by the user's body normally bind to. Opioids also interfere with another neurotransmitter, GABA, which in turn increases the level of dopamine, a neurotransmitter that results in the euphoric feeling.
Other illegal drugs also affect the brain. Another example is amphetamines. The ]]>Canadian Institutes of Health Research and the Canadian Institute of Neurosciences, Mental Health and Addiction]]> point out that amphetamines resemble the structure of dopamine, so when someone uses amphetamine, the drug pushes out stored dopamine, causing the brain to use the neurotransmitter.
But how does drug addiction affect someone in the long-term? When someone continues to use a drug, it can cause changes to the brain. The ]]>National Institute on Drug Abuse]]> explains that doctors can use positron emission tomography (PET) to see changes in the brain from drug use; for example, people addicted to methamphetamine or heroin had lower levels of a type of dopamine receptor called the D2 receptor. As a person uses more of the drug, she built up a tolerance, meaning she needs to use more of the drug to get the same high as before.
In a new study funded by the National Institute on Drug Abuse, the researchers note that a regulatory protein may indicate if a person will become addicted to a drug, in particular cocaine.