Throughout history, people have been using psychoactive substances to induce altered states of consciousness and see the world in a new, different way. For example, the Aztecs in Mexico took peyote and teonanacatl, a type of edible cactus and mushrooms, respectively, which can be used as drugs that make you hallucinate. In the Romantic era, many poets and writers (e.g. John Keats, Charles Dickens or George Elliot) did opium. In the counterculture of the 1960s people commonly experimented with recreational drugs, such as marihuana or LSD.
People use psychoactive substances for several reasons, especially to feel good, to relieve emotional pain and forget things for a while, but also to seek hallucinations, a state of euphoria, tranquillity or even stupor. Whatever the reason, the effects of substance use are always worse than the problem you are trying to resolve.
Psychoactive substances impair the brain mechanisms that are involved in decision making. In addition, they stimulate the brain’s reward system. They trigger the release of dopamine, a feel-good neurotransmitter, in the basal ganglia, which is responsible for, among others, controlling reward. Released dopamine produces immediate but temporary pleasurable feelings that come from using a substance. When more substance is consumed, dopamine is released again and the resulting pleasurable feelings return. As a result, this experience reinforces the substance use, making you crave it more and more until you become addicted to it.
When people talk about addiction, what they usually think of right away is substance use yet in recent years this term has expanded and come to include non-substance-related behaviours, such as gambling, gaming, shopping or Internet use. However, DSM 5 (the current edition of “The Diagnostic and Statistical Manual of Mental Disorders”) includes only gambling as a form of addiction that doesn’t involve the use of a substance. Other non-substance-related behaviours require further research before they are considered mental disorders in the DSM.