Mental illness and substance abuse disorders are often found in the same individual and there has been a great deal of investigation into discovering why this is true. Rather than a single “smoking gun,” scientists believe that there might be many possible causes for the correlation between substance abuse and mental illness. For some people, one condition might cause the other, while other people might be more vulnerable to both conditions right from the start.
According to the National Institute on Drug Abuse (NIDA), it is believed that between 40 to 60 percent of a person’s vulnerability to addiction is caused by genetic factors. Some of these factors dictate how the human body responds to drugs directly, such as making certain drugs more pleasurable, which increases the likelihood of substance abuse. But other genetic traits are more indirect. People with genetic traits that make them predisposed to risk-taking and thrill-seeking are more likely to try drugs than people without those genetic traits. Personality traits that increase the risk of drug addiction may also increase the risk of mental illness. For example, a person who is prone to suffer stress is more likely to develop a mental illness due to stress and also more likely to take drugs to cope with stress. When genetics cause people to have traits that increase their risk of both substance abuse and mental illness, they are genetically predisposed to comorbidity.
Nevertheless, not all physical traits that increase the risk of comorbidity can be found in a person’s genes. The parts of the brain that use dopamine are highly vulnerable to both mental illness and substance abuse. Dopamine is a neurotransmitter that delivers messages of pleasure and comfort throughout the brain. When these messages are not delivered properly throughout the brain, it can cause a wide range of mental illnesses, including depression and schizophrenia. Many drugs target dopamine receptors in the brain to produce their euphoric effects. These drugs also interfere with the dopamine system, causing drug cravings and addiction. The fact that the same parts of the brain can cause both disorders suggests that when conditions are ripe for one disorder, they are also ripe for the other.
Even when a person is not predisposed toward one condition or the other, mental illness and substance abuse can bring each other about by the environmental conditions they create. When a person develops a substance abuse problem, they often become unable to hold a job, fulfill their family responsibilities and generally lose their ability to function in society. All of these environmental conditions can make a person develop a mental illness. Likewise, when a person develops a mental illness, they can experience a similar breakdown in their ability to cope with day-to-day life, creating the environmental conditions that encourage substance abuse. Because both conditions are often caused by the very environmental conditions that they create, one is naturally bound to result from the formation of the other.
Once comorbid conditions take root, they require specialized dual diagnosis treatments to be overcome. If you or someone you know is suffering from comorbid conditions, call the Arizona Drug Addiction Helpline for treatment options in your area.