Dual Diagnosis

Dual Diagnosis describes people who have mental heath problems and drug or alcohol problems. The mental health problems may include schizophrenia, depression, bipolar disorder or Personality Disorder.

Having a mental health diagnosis significantly increases your risk of misusing alcohol and drugs. Research carried out by the Royal College of Psychiatry (2002) found that people with a diagnosis of schizophrenia are more likely to misuse alcohol. They are also 6 times more likely to use street drugs (Chrome, 2003).

The following psychiatric problems are common in dual diagnosis:

  • Depressive disorder such as depression and bipolar disorder
  • Anxiety disorders including generalised anxiety disorder or panic disorder
  • Obsessive Compulsive Disorder and phobias
  • other psychiatric disorders such as schizophrenia and Personality Disorders.

A study carried out in the US by the Epidemiological Catchment Area Study (1994) found that 47% of people with schizophrenia have Dual Diagnosis.

What is drug misuse?

two men on beach

Many of us use legal drugs like caffeine, nicotine, or alcohol without much thought. Their use is socially acceptable and, in some circumstances, encouraged. We may even consume unwise levels or have a temporary dependency without having a long-term dependency problem. It is important to note that some people may also take illegal drugs occasionally without being dependent on them – e.g a recreational cocaine user.

The line between use and misuse is a fine one and will vary from individual to individual. However, a useful working definition of use and misuse has been developed by the drugs agency Drugscope:

Drug use: this refers to the taking of a drug, either by swallowing, smoking, injecting or any other way of getting it into the bloodstream. Drug use refers to drug taking that, although it has some risk, is not necessarily wrong or dangerous. The term does not imply that drug taking is wrong and is therefore preferred by many not wishing to value-judge the taking of drugs.

Drug misuse: implies use outside medical use and which is harmful or done in a wrong way. It refers to use that is dependent or part of a problematic or harmful behaviour. This is preferable to the older term drug ‘abuse’ which can imply a moral judgement.

(Information taken from the Dual diagnosis toolkit (702 kb) [pdf], a practical guide for professionals and practitioners, 2004).

Risk of harm

Both substance misuse and untreated mental illness are associated with a greater risk of suicide. It is estimated that 16% of all substance misusers will take their own lives. There is an increased risk of suicide in young people diagnosed with schizophrenia who also use drugs or alcohol. Substance misuse is associated with 37% of all suicides and 77% of people with schizophrenia who takes their own lives are male (Department of Health, 2002).

Dual Diagnosis is also associated with an increased risk of violence to others. Aggression is another factor which increases the risk of suicide (Scott, 1998).

National Advice Service factsheets

The information in this section is taken from the NAS factsheet, which you can download in pdf format and print for individual use (external link to Mental Health Shop):

Dual diagnosis factsheet 

For further information on the references given above, contact the National Advice Service.