The harmful effects of such addiction are plenty; for instance, it causes a person’s brain and behavior so that there is no control over its use. Heavy substance abuse changes a lot of body systems, but primarily it is the brain which suffers from the most damage. An addiction in simpler terms is a pathological disease of one’s brain which affects one’s behavior. An early use of substance or alcohol can seem to be for socialising or enjoyment, however, in fact, it is the start of a change which can progress over time. With time more of the substance is required to get an effect.