Through the research and information provided in this course, I understand why such a disorder is difficult to treat and overcome. With SUDs, scientists have found that when a foreign substance such as drugs, alcohol, or opioids is introduced into the body and used regularly, the brain alters its chemistry to crave this substance. During this chemical change, the brain releases an excessive amount of dopamine, causing the person to become addicted. The body goes through a phase where it develops a tolerance to the amount of substance used and more is needed to achieve the same effect as if a smaller amount were ingested. The body also desires the substance to function normally. This change can happen quickly or there can be a small subtle change over time. Regardless of how weak the changes, the brain develops an uncontrollable, compulsive response to constant drug use due to the adaptation of dopamine receptors to the substance. Scientists have also shown that addiction does not necessarily have to be linked to a substance, but can be related to impaired control or some sort of persistent behavioral action. In behavioral addiction there is no craving, but just like in chemical addiction, the brain circuitry and chemicals are