One of the greatest challenges in the diagnosis and treatment of addiction is when an addiction illness exists at the same time as another mental illness. These disorders can disguise each other's existence and make treatment for either condition less effective than it would otherwise be. Nevertheless, the high rate at which mental illness and addiction do co-occur has made it a prominent topic among those who research and treat substance abuse and addiction. Cause and Effect The Journal of the American Medical Association reports that approximately 50 of people who have been diagnosed with a severe mental illness are also affected by a substance use disorder. The Journal also shows that individuals with substance use disorders are affected by mental illness in high percentages: about 37 percent of alcoholics and 53 percent of drug abusers. As these numbers would suggest, co-occurring mental illness and substance use disorders are frequently very closely connected. The disorders may have a cause and effect relationship, and some researchers are now exploring the hypothesis that, in certain cases, mental illness and addiction may really be the same disorder. Physicians and researchers currently believe that substance abuse and mental illness can both assert a cause and effect relationship on each other. Some patients suffering from mental illness may attempt to self-medicate with damaging substances or behaviors. Other mental illnesses, such as bipolar disorder, may lead people to engage in risky behaviors such as drug abuse that they would not otherwise try. In some instances, substance use disorders may also lead to mental illness. Substance abuse may lead directly to the development of disorders such as depression or anxiety, or it may trigger an even more serious condition to which the individual was already predisposed. In some cases, mental illness may be present but relatively dormant until substance abuse triggers the onset of more severe symptoms. Finally, research is currently underway to explore the relationship between bipolar disorder and alcoholism to discover if there is any truth to the hypothesis that bipolar and certain kinds of addiction are a single disease. This hypothesis and research was triggered by the enormous rate at which alcoholism occurs among those with bipolar disorder - more than seven times as frequently as in the general population. So far, research is showing some strong similarities in the brain chemistry of both addiction and mental illness. Common Risk Factors Researchers are also examining the ways in which addictions and mental illness may have common risk factors that increase the likelihood of co-occurrence. Genetics can predispose individuals to mental illness or to addiction, and some of these genetic factors may overlap. Overlapping vulnerabilities could mean that some individuals are greatly at risk for developing multiple disorders. Brain function may also predispose some individuals to co-occurrence, if they show abnormalities with the reward and stress functions that are strongly related to addiction. Environmental and developmental factors may also increase a person's risk of multiple disorders. Trauma or other stressors can be risk factors for both addiction and other mental illness, and multiple conditions may arise simultaneously as a result of a trigger. Drug use or mental illness in a person's developmental years may also make them more susceptible to the other in later years. Treatment for Co-Occurrence Patients with dual diagnoses of substance use disorders and mental illness have long been a challenge to treat. Even the diagnosis can be extremely tricky, since some symptoms of addiction or of withdrawal can strongly resemble the symptoms of another mental illness. The most successful treatment programs will screen patients carefully for multiple conditions, to increase their chances of recovery. Treatment attempts that fail to address one or more co-occurring conditions are likely to be ineffective. Co-occurrence, also called co-morbidity, may complicate the use of medications that have proven effective for treating addictions or mental illnesses. Although certain medications have been shown to be effective for treating isolated disorders, very few studies so far have examined the effects of these drugs on co-morbid patients. It's possible that some medications may be effective at treating multiple conditions simultaneously, but co-morbid conditions may also lead to ineffective treatment or complications. The most successful treatments for co-morbid disorders are integrated treatments that address each individual's conditions at the same time. Even when one condition is believed to have led directly to a second disorder, treating one illness independently will not necessarily lead to a resolution for both problems.