Substance-related disorders are defined by the Diagnostic and Statistical Manual (DSM) as substance use disorders (including substance dependence and substance abuse) and substance-induced disorders.
The term substance-related disorders is an umbrella classification that defines a category in the DSM, a manual that has changed and grown with society and further understanding. The current manual is the DSM-IV-TR. It is a used by psychologists, psychiatrists, therapists, physicians, clinicians, and anyone else responsible for diagnosing a wide range of mental illness and substance-related disorders.
Substance-related disorders are those which are related to using psychoactive substances. People with a substance-related disorder can be using legal and/or illegal intoxicants, but the main factor is that their relationship with the substance creates some sort of problem, whether that is emotional, physical, or any combination thereof, and more. Substance-related disorders are quite common. The DSM-IV-TR further defines the characteristics of substance-related disorders by providing generic definitions and criteria for dependence, abuse, intoxication, and withdrawal for almost all substances of abuse. These include alcohol, amphetamines, cocaine, opioids, phencyclidine, hallucinogens, pills, nicotine, inhalants, caffeine, cannabis, sedative hypnotics, and polysubtance use. It is within these criteria that diagnosing a substance-related disorder is defined.
It is extremely important that the clinician has the knowledge and ability to properly diagnose someone. For example, if a patient was presenting as paranoid, hearing voices, unkempt, delusion, and extremely polite and charming, the clinician/psychiatrist/physician would have to be able to diagnose this person appropriately. If they do not ask any questions about substance use then the person can get incorrectly diagnosed with a psychotic disorder instead of amphetamine intoxication*. Amphetamine induced psychosis is hard to distinguish from schizophrenia.
At the end of a session, a person may be diagnosed with substance dependence, which is a substance-related disorder. The line between substance use and abuse is thin, as is the line between clusters of symptoms caused by substances and symptoms of mental health disorders. The net thrown by the category of substance-related disorders is quite large. It is important that the person is carefully assessed because without an accurate diagnosis healing is going to be difficult if not impossible.
Substance-related disorders have been more finely categorized over the past years. The next DSM release is supposed to further change some of the categories for substance-related disorders, which is partly aimed at helping to reduce stigma for substance-related disorders. As with other mental illness, substance-related disorders are biological changes and differences in an individual's brain.
*It should be noted not all persons with amphetamine use disorders or psychotic disorders appear unkempt or with all of these symptoms. This is only an example.