Explain the psychology and physiology of addiction.
Psychological addiction can be differentiated from physiological addiction where it has to do with the mental state of the user being affected in terms of drug use where he desires or is compelled to use a drug repeatedly. Physiological addiction has to do with the physical part of the user being affected (Nestler, Hyman & Malenka, 2009). The user gets adapted to a drug and whose cells cannot function without the drug. In turn, the person experiences withdrawal symptoms once the drug is inaccessible or out of reach. These symptoms include nausea, tremors and chills.
Identify specific drug substances covering the following categories: stimulants, depressants, narcotics, hallucinogens, and cannabis.