Drug dependence

Drug dependence is a chronic, relapsing brain disease characterized by long-term or repeated use of a substance, leading to mental and physical dependence. Individuals are compelled or periodically driven to use the drug, despite no medical need, to achieve the euphoria associated with its use or to avoid the distress of withdrawal. Most drugs that cause dependence act on the central nervous system. Key manifestations include periodic intense craving and drug-seeking behavior, and loss of control over drug use.