Substance abuse and mental illness are linked in several ways. Often, suffers of mental illnesses such as depression and post-traumatic stress disorder (PTSD) use alcohol or drugs to self-medicate. Sometimes the drug use itself leads to mental illness, as can happen with prolonged use of hallucinatory drugs. Finally, drug and alcohol addiction themselves are considered mental illnesses in their own right.
The link between substance abuse and mental illness is so prevalent that people who are being treated for drug addiction are often assumed to have underlying mental health issues. Sufferers of anxiety disorders often turn to depressants such as alcohol and prescription narcotics to alleviate stress and aid in relaxation. Likewise, individuals who have chronic depression sometimes rely heavily on stimulants and mood-altering drugs to self-medicate lethargy and ward off unhappiness.
Compounding the issue is the tendency of some drugs to damage the brain, leading to mental illness. Studies have shown that alcohol and heroin use can create brain damage with symptoms similar to those of Alzheimer’s disease. Lysergic acid diethylamide (LSD) is a hallucinatory drug that has been shown to cause both temporary and, in rarer cases, permanent psychosis.
Treating substance abuse often requires the help of trained mental health workers. Rehabilitation clinics are frequently designed to treat substance abuse and mental illness at the same time. The most immediate mental health issues involved with withdrawal from drugs and alcohol include depression, anxiety, paranoia, hallucinations and sleep disturbances. After those symptoms have been treated, underlying chronic mental health problems are often addressed in long-term therapy.
The combination of substance abuse and mental illness often makes it impossible for the sufferer to function normally in daily life. The effects of substance abuse often include difficulty maintaining personal relationships. This often results in the isolation of the addict. Isolation can lead to depression and increased drug and alcohol use. Without intervention, this cycle typically continues and gradually worsens.
Few people who have untreated addiction and mental illness issues can successfully cope in the workforce. Job quality often suffers, sometimes to the point that an employer is forced to terminate the individual. Once again, this can lead to the worsening of both the mental illness and addiction. If this pattern repeats frequently enough, an individual can become unemployable. Without a steady source of income, some addicts are left without the resources to maintain a home.
All of these factors combined make the link between substance abuse and mental illness highly observable in the homeless population. A large percentage of the homeless suffer from both mental illness and drug addiction. Depression and PTSD are common among those in the homeless population, as are alcoholism and — to a lesser extent — drug abuse. The homeless seldom have access to mental health care and, as a result, their mental illnesses and addictions often go untreated.