The term was first used in the USA, in the 1980s, to refer to people diagnosed with psychotic illnesses, who also used illicit drugs or alcohol. (If someone is diagnosed as psychotic, it means they have beliefs or experiences that are not shared by others.)
Today, some mental health professionals have a broader understanding, and may use the term to include, for instance, someone who is depressed and drinking heavily, or using stimulant drugs (such as amphetamine or cocaine) in order to feel more socially confident.
Health professionals sometimes disagree about when to apply the term. Some believe that any substance use by people with mental health problems is likely to lead to increased symptoms, and is therefore problematic. Others accept that drinking and drug use is more common amongst people with mental illness than it used to be, and are more flexible about it.
There is currently no standardised treatment for dual diagnosis, largely because it ranges across such a large number of problems and involves both substance misuse services and mental health services. Researchers are looking at what the best clinical practices might be. It’s currently thought that, in the first instance, mental health services are better equipped than drug services to help people, because of their sphere of expertise.
The term dual diagnosis can mean any two conditions, and can be rather unhelpful. In this context, it means co-existing mental health and alcohol and drug problems. Not all alcohol and drug use will cause problems, but for many it may cause problems to an individuals mental health, physical health or the day to day functioning.
It is important to recognise that there is a broad spectrum of mental health disorders, types of substances used, their effects and potential difficulties. This can range from severe and enduring mental health disorders, such as bi-polar or schizophrenia and heroin or ‘crack’ cocaine misuse, through to the so-called milder mental health disorders, such as anxiety and personality disorders and alcohol and cannabis misuse.
Dual diagnosis is very common. The prevalence of dual diagnosis may effect between 30 and 70 % of those presenting to health and social care settings.
Alcohol and drug use can affect us in a number of different ways. Substance use may lead to or exacerbate mental health problems. Likewise psychiatric disorders may lead to harmful or dependent substance use. It can be difficult to say with certainty the precise nature of this relationship. The ‘chicken’ and ‘egg’ syndrome.
Assessing which condition is ‘primary’ diagnosis and which is ‘secondary’ diagnosis may be possible. But, all too often they are used as a barrier for accessing treatment. It is important that the needs of the individual are placed first, and treating both the mental health and alcohol and drug difficulty together should be the treatment of choice. The emerging evidence suggests components of ‘An Integrated Treatment Approach’ have better outcomes.