The high rate of co-morbid occurrences and conditions of Substance Addiction with Mental Illnesses has been an intriguing field of study by research scientists and practicing mental health professionals worldwide and findings have been alarming. National Institute on Drug Abuse (NIDA) indicates in a 2007 research update that six in ten people abusing Substance also suffer from a form of mental illness. While people with anxiety or mood disorders are twice as prone to be drug addicts, another perspective saw drug addicts to be twice as prone to have anxiety or mood disorders.

The cause of co-morbidity of Substance Addiction with Mental Illness does not lie in either one or both of the conditions alone. Research indicates that genetic, biological and environmental factors play an important role in giving rise to both conditions, in most cases eventually. The variant of the gene responsible in the individual to cause schizophrenia proper, is also activated by some powerful drugs to create the same hallucinogenic and psychotic effects that can rarely be reversible. This prolonged abnormal state of mind and symptoms can intermittently give rise to other clinical conditions like severe paranoia, mood disorder, depression and anxiety. The brain in turn functions in a similar manner, where certain common areas are affected by both drugs and mental illness. This means that Substance Abuse can seriously alter the brain which may eventually risk a mental illness. Environmental factors like stress and trauma are also known to have played a great role in leading to this co-morbid condition. Co-morbid conditions of Substance Addiction with Mental Illness are generally prevalent among teenagers, but this condition may be carried on into the further years of life.

Complications arising due to the interacting symptoms between Drug Addiction with Psychiatric Illnesses have required dedicated research, complicated mechanisms of evaluation, treatment and rehabilitation for the addict/patient. Not all treatment centers today yet, is equipped or able to treat both conditions together effectively, but there are some hospitals and rehabs that have the expertise and competent medical staff, and are able to treat this co-morbid condition effectively and with good results.