SCIE Research briefing 30: The relationship between dual diagnosis: substance misuse and dealing with mental health issues

By Ilana Crome and Pat Chambers, with Martin Frisher, Roger Bloor and Diane Roberts

Published January 2009


This briefing examines the issues presented by service users with dual diagnosis for UK practitioners in health and social care. Confusingly, the term ‘dual diagnosis’ is used to describe several combinations of physical, psychological or developmental conditions; but for the purpose of this briefing, it refers to the co-existence of substance misuse and mental health problems. This briefing considers all age groups and uses the term ‘substance’ to refer to illegal or illicit drugs; alcohol; nicotine and prescription drugs. The terms ‘substance’ and ‘drug’ are used interchangeably. ‘Mental health problems’ refers to severe or enduring conditions, while ‘substance misuse’ refers to chronic or complex substance use problems. The briefing does not consider specific pharmacological or other treatment interventions in detail, but focuses on issues arising at the health and social care interface. It draws on research and literature from other countries, including the US where the majority of research on dual diagnosis has been conducted; to provide an overview for health and social care practitioners in the UK. Where there are gaps in the research, for example, in regard to service user involvement, recovery approaches and personalisation of services, the briefing draws upon evidence from relevant fields such as mental health and substance misuse. Throughout this briefing the terms, patient, client, and service user are used interchangeably to reflect the different usages prevalent within different sectors of health and social care.

Key messages

  • The prevalence of co-existing mental health and substance use problems (termed ‘dual diagnosis’) may affect between 30 and 70 per cent of those presenting to health and social care settings.
  • There is growing awareness of the serious social, psychological and physical complications of the combined use of substances and mental health problems.
  • Given the multiplicity of social, familial and economic problems associated with dual diagnosis, social workers have a distinctive role to play in multi-agency work.
  • Interprofessional training and working, encompassing statutory and non-statutory sectors is essential.
  • Knowledge of screening and assessment for dual diagnosis should be core training elements for health and social care practitioners. The effectiveness of treatment and other interventions is improving.
  • Service provision should actively engage users and carers from initial assessment to continuity of long-term care. The importance of understanding and working with service user’s experience and perspective cannot be underestimated.
  • Raising awareness among non-professionals, including carers, can make a major contribution to improved service access and treatment.


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  • The relationship between dual diagnosis: substance misuse and dealing with mental health issues