Substance use refers to a disorder in which the use of one or several substances leads to clinically significant distress or impairment. Its characteristics are a pattern of continued pathological use of non-medically indicated drugs, medication resulting to a recurring negative social consequence as a result of the drug used.
Substance dependency, on the other hand, refers to using of a particular substance for a long period such that one depends on it for normal survival. One may develop tolerance to the substance such that the person shows withdrawal symptoms. It means that, the person is not able to do normal things without using the substance in question.
Substance abuse is the patterned use of particular substances using methods that are harmful to the person. It also includes the use of more than the required amounts leading to negative effects to the person. In most cases, drug abuse leads to drug dependence and addiction.
Drug addiction refers to continues and repetitive behavior of using a particular substance despite the adverse consequences (Angres DH, and Bettinardi-Angres K, October 2008) or severe neurological impairments prompting the drug addiction. The addiction could vary greatly depending on the substance in question. The impacts are also different. These include; food addiction, drug addiction, computer addiction, gambling addiction, etc. Drug addiction is associated with denial of the excessive dependency, and the consequences.
The diagnosis and treatment of persons who use substances present a huge challenge. It is because the substances abused vary from normal basic needs as food to complex drugs as cocaine. In some instances, the substances are prescribed by doctors, and the person abuses them in secrecy. The levels of abuse are also difficult to establish except for advanced levels. The effect of withdrawal from drugs has profound impacts on a person and may result to other psychological disorders; hence taking care is not optional.
Angres DH, Bettinardi-Angres K (October 2008). "The disease of addiction: origins, treatment,
and recovery". Dis Mon 54 (10): 696–721.