English 
தமிழ் 
Summary People who are addicted cannot control their need for alcohol or other drugs, even in the face of negative health, social or legal consequences.
The illness becomes harder to treat and the related health problems, such as organ disease, become worse. Addiction is a chronic, but treatable, brain disorder. People who are addicted cannot control their need for alcohol or other drugs, even in the face of negative health, social or legal consequences. This lack of control is the result of alcohol- or drug-induced changes in the brain. Those changes, in turn, cause behavior changes.
The brains of addicted people have been modified by the drug in such a way that absence of the drug makes a signal to their brain that is equivalent to the signal of when we are starving. It is “as if the individual was in a state of deprivation, where taking the drug is indispensable for survival. It’s as powerful as that.”
Addiction grows more serious over time. Substance use disorders travel along a continuum. This progression can be measured by the amount, frequency and context of a person’s substance use. As their illness deepens, addicted people need more alcohol or other drugs; they may use more often, and use in situations they never imagined when they first began to drink or take drugs. The illness becomes harder to treat and the related health problems, such as organ disease, become worse.
This is not something that develops overnight for any individual. Generally there’s a series of steps that individuals go through from experimentation and occasional use [to] the actual loss of control of use. And it really is that process that defines addiction.
Symptoms of addiction include tolerance (development of resistance to the effects of alcohol or other drugs over time) and withdrawal, a painful or unpleasant physical response when the substance is withheld. Many people with this illness deny that they are addicted. They often emphasize that they enjoy drinking or taking other drugs.
People recovering from addiction can experience a lack of control and return to their substance use at some point in their recovery process. This faltering, common among people with most chronic disorders, is called relapse. To ordinary people, relapse is one of the most perplexing aspects of addiction. Millions of Americans who want to stop using addictive substances suffer tremendously, and relapses can be quite discouraging.
