This article explores the question of why, when exposed to drugs, some individuals become addicted while others do not. Several studies have established that drug addiction is a function of genetic, environmental, and developmental factors, but the specific influence of each factor is not well understood. It is estimated that genetic factors contribute up to 60% of the variability in the risk of addiction. Brain development factors are also an important predictor of drug addiction.
The article notes that mental disorders such as depression, conduct disorder, attention deficit hyperactivity disorder, and schizophrenia are major risk factors for drug addiction. This phenomenon can be viewed in two ways: that there is a high prevalence of drug abuse in the mentally ill, or as a high prevalence of mental disorders in drug abusers. In any case, both views suggest that people with mental disorders and drug abusers have similar brain chemical.
The identification of neurobiological correlation in addiction is the first step in understanding how to best treat drug addiction. Volkow finds that drug-induced increases in dopamine undermine the reinforcement responses to drug abuse. Repeated drug use is believed to result in an adaptation in the brain that involves a loss of control, reduced sensitivity to nondrug reinforcers, and a fixated high motivational value of the drug – all of which leads to compulsive drug use.
The identification of common neurobiological substrates across various drug addictions suggests that in some cases, it may be possible to develop medications that are beneficial for more than one type of addiction. Furthermore, recent advances in genetics may make it possible to identify genetic factors that predict which individuals may have a favorable response to specific medications for treatment.
All in all, the complex behavioral consequences of addiction would require both pharmacological and behavioral treatments for effective treatment.
I personally know a friend who is especially prone to abuse substances and enjoy the effects of them. She also happens to be mentally 'unstable.' Although I am not sure whether the drugs have caused this or that she has always been mentally unsound. Nonetheless, the article has shown that there is a strong correlation between people with mental disorders and people who are prone to abuse drugs.