Lighting Up the Craving-reward Pathway
One way in which drugs affect the brain is by flooding it with the euphoria-inducing chemical dopamine. Over time, the more drugs that are used, the less dopamine is produced naturally – so users need more drugs to achieve the same state of euphoria. When an addict abstains, levels of glutamate, the excitatory neurotransmitter responsible for memory and learning, start to rise, causing extra anxiety and amplifying craving in the user. The diagram here depicts the approximate regions in the brain where these processes take place.