"187 That is why addiction is a brain disease. As a person’s reward circuitry becomes increasingly dulled and desensitized by drugs, nothing else can comp ete with them — food, family, and friends lose their relative value, while the ability to curb the need to seek and use drugs evaporates. Ironically and cruelly, eventually even the drug loses its ability to reward, but the compromised brain leads addicted p eople to pursue it, anyway; the memory of the drug has become more powerful than the drug itself. When does drug abuse become drug addiction? It rarely happens with the first use of a drug. Drug abuse and drug addiction can be thought of as points along a continuum. Any use of a mind - altering drug or the inappropriate use of medication (either prescription or over - the - counter drugs) is drug abuse , but the point when drug abuse becomes drug addiction is less clear. Different people may reach the point of ad diction at different stages. Scientists continue to investigate the factors that contribute to the transition to drug addiction. Drug addiction is defined as the continued compulsive use of drugs despite adverse health or social consequences. Drug - addicte d people have lost control of their drug use. Individuals who are addicted to drugs often become isolated from family or friends, have difficulty at work or school, may commit crimes, and become involved with the criminal justice system. For a person addic ted to drugs, continuing to take them becomes the primary focus in life. Certain drugs, including opioids and alcohol, cause strong physical reactions in the body when drug use stops. When a person addicted to heroin stops taking heroin, he or she can exp erience a variety of symptoms ranging from watery eyes and a runny nose to irritability and loss of appetite and then diarrhea, shivering, sweating, abdominal cramps, increased sensitivity to pain, and sleep problems. In general, withdrawal from heroin mak es people feel miserable. Withdrawal from alcohol can cause serious effects such as seizures and even death. Withdrawal from other drugs, such as cocaine and amphetamines, does not lead to strong physical reactions, but it may make the person feel depresse d or lethargic. For most drugs, physical withdrawal symptoms can usually be controlled effectively with medications. Even though withdrawal from some drugs does not cause the person abusing them to have physical reactions, stopping drug use is difficult be cause of the changes the drugs have caused in the brain. Once the drugs stop, the person will have cravings , or intense desire for the drugs. Craving arises from the brain’s need to maintain a state of homeostasis that now relies on the presence of the dru g. A person may experience cravings at any stage of drug abuse or addiction, even early in the experimentation phase of drug abuse. Cravings have a physical basis in the brain. Using PET imaging, scientists have shown that just seeing images of drug paraph ernalia can stimulate the amygdala (part of the brain involved in emotional memory) in an addicted person. Drugs of addiction do not merely cause short - term changes in an individual’s cognitive skill and behavior. A drug “high” lasts a short time, ranging from less than an hour to 12 hours, depending on the drug, dose, and route of administration. The changes in the brain that result from continued drug use, however, can last a long time. Scientists believe that some"