Anderson Paul
In general medicine, Feinstein has defined comorbidity as, any separate and supplementary disorder that has coexisted or that may occur while the patient is suffering from the index disease under study. In recent times this expression is frequently used in clinical psychiatry to describe patients who receive a medical diagnosis in addition to their psychiatric disorder but much more frequently patients who are diagnosed with two or more psychiatric disorders. Dual diagnosis are associated with a number of undesirable sequels comprising higher dose and/or number of medicines, non-compliance, psychosocial problems, depression, deliberate self-harm, relapse, increased load on family and vagrancy. In addition, they often have a poorer treatment outcome than those with a single diagnosis of a mental disorder.