Abuse of psychoactive substances has been reported nearly all human societies, cutting across all sexes, socio-economic strata, and works of life, with attendant personal and social effects. To the individual, it leads to chronic diseases that change both brain structure and function; just as cardiovascular disease damages the heart and diabetes impairs the pancreas, addiction hijacks the brain. This happens as the brain goes through a series of changes, beginning with recognition of pleasure and ending with a drive toward compulsive behaviour (Harvard Health Publication, 2013), resulting in addiction. Socially, it affects interpersonal relationships, occupational functioning, etc.
The DSM-V described these conditions as substance-related and addictive disorders which encompass ten separate classes of drugs, which are actually not fully distinct. Accordingly, all drugs taken in excess have in common direct activation of the brain reward system, which is involved in the reinforcement of behaviours and production of memories. They produce such an intense activation of the reward system that normal activities may be neglected. For DSM-V, instead of achieving reward system activation through adaptive behaviours, drugs of
abuse directly activate the reward pathways. The pharmacological mechanisms by which each of drugs produces reward are different, but the drugs typically activate the system and produce feelings of pleasure, often referred to as “high’. Also, the DSM-V holds that individuals with lower levels of self-control, which may reflect impairments of brain inhibitory system, may be particularly predisposed to developing substance use disorders, suggesting that the roots of substance use
disorders for some persons can be seen in behaviours long before the onset of the actual substance use itself (American Psychiatric Association, 2013).