what is the national institute on drug abuse and what are its purposes?

What is the purpose of the national institute on drug abuse?This is the question that have been asked by many.The National Institute on Drug Abuse (NIDA) is a United States federal-government research institute whose mission is to "lead the Nation in bringing the power of science to bear on drug abuse and addiction."

One of NIDA's most important achievements has been the use of science to clarify central concepts in
the field of drug abuse...
When NIDA began, correct approaches to drug policy and drug treatment were often thought to hinge on determining whether a particular drug was "physically addicting" or only "psychologically addicting." We now know that addiction has biological, behavioral and social components. It is best defined as a chronic, relapsing brain disorder characterized by compulsive, often uncontrollable drug craving, seeking, and use, even in the face of negative health and social consequences. NIDA-supported research has also shown that this compulsion results from specific drug effects in the brain. 

This definition opens the way for broad strategies and common approaches to all drug addiction.