Addiction can be defined as a state in which an individual engages in compulsive behavior craving for a particular substance or action. The craving leads to reinforcement of the behavior and there is a loss of control over one’s impulse to seek and consume the focus of addiction.


People start taking drugs for various reasons – to feel good, to have a new kind of experience, or to share that experience with others; some may take it to lessen anxiety, worries, fears, depression, etc. Some of these users are victims of sexual assault, physical violence, or emotional violence. Addiction represents a complex interplay between biological, genetic and environmental factors. So if someone has a genetic predisposition to having an addiction, it may not actually happen because the environmental factors may not be there to facilitate that. Usually, an environmental trigger (peer pressure, trauma, abuse) or some environmental exposure precipitates addiction in some who might have that genetic predisposition.

Avoiding withdrawal effects becomes a primary motivating factor for the individual to seek and take drugs

Facilitation is an important concept in the development of addiction. Environmental factors that enable the use of drugs – using gateway drugs, smoking, exerting peer pressure, drugs being given away for free, etc. are some examples of this phenomenon. While these may not necessarily affect others, it definitely pushes someone with a genetic predisposition closer to the edge, where they “get hooked” on it.


Drugs of abuse hijack brain circuits designed for survival and strongly influence motivational priorities. Dopamine is the main neurotransmitter implicated in these processes. Among all the drugs of abuse, heroin use is said to have the greatest dopamine reward. When a user abuses a hard drug like heroin, the body adapts to the presence of these substances (up-regulating receptors) and, over time, the same amount of substance does not produce the same effect, so they take more. This is called developing tolerance. Not taking that amount leads to withdrawal symptoms; this called dependence. Avoiding withdrawal effects becomes a primary motivating factor for the individual to seek and take drugs. This leads to risky drug-seeking behavior, of which is using shared needles. This behavior puts these users at a very high risk of contracting HIV infection. A study performed in 1993 showed that 22% of 103 out-of-treatment people injecting heroin contracted HIV as compared to 3.5% of 152 who received methadone, suggesting medication-assisted treatment can reduce injection-related HIV risk in these patients.


There are several other consequences and complications of substance addiction – mental illnesses, malnutrition, delinquency, violence, crime, relationship breakdown, etc. Having a deeper understanding of the mechanism of substance addiction allows us to address these challenges and find ways to prevent or manage these conditions. It helps us remove the taboo associated with it in the society and drive policy that supports more funding for prevention programs as well as research in novel therapies and intervention programs that can help those who are suffering from this disorder.