Disorders relating to maladaptive behaviours resulting from regular and consistent use of the substance involved are called substance abuse disorders. These disorders include problems associated with using and abusing such drugs as alcohol, cocaine and which alter the way people think, feel and behave. There are two sub-groups of substance-use disorders: (a)Substance Dependence refers to intense craving for the substance to which the person is addicted The person shows tolerance, withdrawal symptoms and compulsive drug taking. Tolerance means that the person has to use more and more of a substance to get the same effect. Withdrawal refers to physical symptoms that occur when a person stops or cuts down on the use of a psychoactive substance, i.e., a substance that has the ability to change an individual's consciousness, mood and thinking processes. (b)Substance Abuse refers to recurrent and significant adverse consequences related to the use of substances. People, who regularly consume drugs, damage their family and social relationships, perform poorly at work, and create physical hazards. Substance abuse disorders are a joint result of physiological dependence and psychological dependence. Physiological dependence refers to withdrawal symptoms, i.e., the excessive dependence of the body on drugs, Psychological dependence, on the other hand, refers to the strong craving for a drug because of its pleasurable effects.The three most common forms of substance abuse: •Alcohol abuse and dependence • Heroin abuse and dependence •Cocaine abuse and dependence Alcohol Abuse and •People, who abuse alcohol, drink large amounts regularly and rely on it to help them face difficult situations. •Eventually the drinking interferes with their social behaviour and ability to think and work •For many people the pattern of alcohol abuse extends to dependence. That is their bodies build up a tolerance for alcohol and they need to drink even greater amounts to feel its effects. •They also experience withdrawal responses when they stop drinking. Alcoholism destroys millions of families and careers. •Intoxicated drivers are responsible for many road accidents. •It also has serious effects in the children of persons with this disorder. •These children have higher rates of psychological problems. Particularly anxiety. • Depression phobias afid substance-related disorders •Excessive drinking can seriously damage physical health. Some of the ill effects of alcohol can be been on health and psychological functioning.Heroin Abuse and Dependence •Heroin intake significantly interferes with social and occupational functioning. •Most abusers further develop a dependence on heroin. revolving their lives around the substance, building up a tolerance for it. and experiencing a withdrawal reaction when they stop taking it. •The most direct danger of heroin abuse is an overdose, which slows down the respiratory centres in the brain, almost paralyzing breathing arid in many cases causing death. •Regular use of cocaine may lead to a pattern of abuse in which the person may be intoxicated throughout the day and function poorly in social relationships and at work. •It may also cause problem in short-term memory and attention. •Dependence may develop, so that cocaine dominates the person's life, more of the drug is needed to get the desired effects and stopping it results in feeling of depression. fatigue. sleep problems. irritability and anxiety •Cocaine poses serious dangerous effects on psychological functioning and physical well-being.