When a person’s use of alcohol or another substance (drug) leads to health issues or problems at work, school, this has become a disorder. An uncontrolled manner and repeated use of substance (drug) despite harmful consequence. Substance abuse can cause changes in how the brain functions, brain imaging studies shows that changes occurs in the areas of the brain that is related to judgment, decision making, learning, memory, and behavioural control. Changes in the brain’s structure and function are what cause people to have intense cravings for more of the substance. People with a substance use disorder may have symptoms like distorted thinking and behaviours, changes in personality and abnormal movements.