The term dual diagnosis is used to describe the comorbid condition of a person considered to be suffering from a mental illness and a substance abuse problem. There is considerable debate surrounding the appropriateness of the term being used to describe a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcoholism, or it can be restricted to specify severe mental illness and substance misuse disorder. Dual diagnosis is also a term used for people with an intellectual disability and diagnosed with a mental illness. Making a dual diagnosis in substance abusers is difficult as drug abuse itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness.