Concurrent Disorders 101

Concurrent disorders, also known as dual disorders, dual diagnosis, and co-occurring disorders, refers to the co-existence of a psychiatric disorder, such as anxiety, depression, schizophrenia, or post-traumatic stress disorder, alongside substance use disorder. For example, someone with both depression and alcohol addiction could be said to have a concurrent disorder.


The cross-sectional 2012 Canadian Community Health Survey–Mental Health gives us the estimate that about 282,000 Canadians aged 15 to 64 (1.2%) had experienced both a mood/anxiety disorder and a substance use disorder in the previous year. This is close to the 1.7% prevalence of concurrent disorders seen with the results of the 2002 CCHS Mental Health and Well-being, although, notably, the 2002 survey assessed a slightly different range of mental illnesses in their definition of concurrent disorders. Although women are more likely to have a mood disorder and men more likely to have a substance use disorder, the prevalence of concurrent disorders does not vary by sex.


Treating concurrent disorders is complex. In the best case scenario, the treatment is as holistic as possible, integrating the treatment of both concurring disorders, rather than separately treating each. This is because the symptoms, contributing factors, and often the treatment recommendations themselves often overlap between the two disorders. The specifics of treatment for each individual will vary; it is often provided in an out-patient setting, but sometimes may involve intensive day or residential programs. A patient-centred approach is recommended; in other words, the health care professionals involved in the treatment plan will work with the patient, partnering in their care with the ultimate goal of empowering self-management. Strategies for treatment may include motivational interviewing, counselling (e.g. to provide cognitive behavioural therapy), emotion regulation skill building, and medication therapies. Depending on the individual, the treatment plan may involve group sessions, or may be entirely one-on-one.