Addiction is a complex phenomenon that affects the brain in multiple ways. After repeated drug use, the brain begins to adapt to dopamine surges, resulting in less dopamine signaling in the brain. Chemical compounds in stimulants, nicotine, opioids, alcohol and sedatives enter the brain and bloodstream after use, interfering with the way neurons send, receive, and process signals through neurotransmitters. This can cause people to lose control of their impulses or want to consume a harmful substance.
Scans show that several different regions and pathways within the brain are affected by addiction, from an increase in neurotransmitters such as dopamine to reduced or increased activity in certain regions of the brain. Chronic overstimulation of the brain interferes with maintaining homeostatic balance, leading to a new balanced set point called allostasis. All addictive drugs affect the brain pathways involving reward, that is, the dopamine system in the reward pathway. Drugs take over amygdala and hippocampal cells to build intense emotional memories of drug experiences. Scientists once believed that the experience of pleasure alone was enough to entice people to continue searching for an addictive substance or activity.
Additional research has been initiated to discover the structural changes that occur in the brain during addiction. The likelihood that the use of a drug or participation in a rewarding activity will lead to addiction is directly related to the speed with which it promotes the release of dopamine, the intensity of that release, and the reliability of that release. Detoxification can take several days to several weeks, depending on the substance and how long a person has struggled with addiction. Identifying what happens in the brain when a drug is inhaled, injected or eaten, why it leads to compulsive drug searching and learning to interrupt that process seems to be the last best hope for a permanent solution to addiction. Many addiction experts suggest that by moving away from your typical environment and its “triggers”, it's easier to stay sober and stay sober. Brain scans can show us the damage caused by addiction, but they can also point us to potential proactive solutions to help people recover and find effective treatments for ongoing addictive behaviors.