Meaning Of Dual Diagnosis

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Meaning Of Dual Diagnosis

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KEY TAKEAWAYS

Dual diagnosis means suffering from a substance/alcohol use condition and a psychiatric condition simultaneously [1].

What Is Dual Diagnosis

Dual diagnosis represents a dual pathology intersection where mental health and substance misuse diagnoses meet.

The interconnected nature and simultaneous timing of the underlying issues make it difficult to understand and treat the condition fully:

Each condition can exacerbate the other, complicating treatment
Patients are likely to be rejected by addiction and mental health programmes until one or the other condition is alleviated
Patients are likely to be misdiagnosed and not receive the correct treatment [2]
Medical professionals in different locations ascribe differing meanings to dual diagnosis, changing treatment priorities and long-term treatment outcomes [3]

Assumed Attributes Of Dual Diagnosis

Professionals typically assume shared characteristics present in dual diagnosis patients:

Difficulty identifying dual diagnosis, particularly if medical professionals are not diagnosing two separate conditions
Limited academic research resources covering the topic definitively
Lack of standardised definition
Potential for misdiagnosis when drug/alcohol abuse is not detected in mental health treatment or vice versa [4]
Difficulties accessing insurance policies that cover dual diagnosis care: insurers may claim that dual diagnosis care was not medically needed [5]
Higher patient complexity and co-morbidity of other issues
Higher chronicity of dual diagnosis compared to other acute conditions [6]
The high degree of person-centred care necessary
The need for completely new or unique therapeutic interventions
The need for different professional teams to collaborate more than normal during treatment
The long-term, dynamic, and continually changing nature of indicators of illness
The need for ongoing re-assessment and re-evaluation of patients' needs
Possibility of combined medications during treatment leading to negative reactions
Possibility of medication typically used to treat one illness exacerbating the other illness
Previously not having received the correct support from either addiction or mental health services [7]

Meaning Of Dual Diagnosis In Professional Assessment Tools

Header	Diagnostic And Statistical Manual Of Mental Disorders (DSM-5)	Addiction Severity Index (ASI)	Clinical Institute Withdrawal Assessment (CIWA-Ar)
Definition	One or more mental health and substance abuse disorders	A drug or alcohol dependency combined with a mental health disorder	Alcoholism combined with mental illness symptoms
How Definition Differs	All forms of mental health and substance abuse are dual diagnosis [8]	Dual diagnosis and co-occurring conditions are the same [9]	Only considers physical symptoms [10]

Header	Severity Of Alcohol Dependence Questionnaire (SADQ)	Assessment Of Dual Diagnosis (ADD)
Definition Of Dual Diagnosis	Alcohol dependency combined with a mental health disorder	Patient must suffer from one or more: Mania, depression, anxiety, PTSD, substance abuse, somatoform disorders, dementia, schizophrenia, personality disorders or eating disorders
How Definition Differs	Primarily focuses on emotional effects of diagnosis [11]	Highlights specific conditions that qualify as dual diagnosis [12]

As Defined By Professionals In The Field

Psychiatrists in the field may use different definitions compared to standardised DSM-5 or other definitions:

Using a 'working diagnosis' even if indicators of illness do not fit the established criteria, in order to progress with treatment [13]
Comparing the severity of mental issues to the severity of substance dependence to organise individualised effective care when a joined-up approach is not available
Considering co-occurring learning disabilities as part of a dual diagnosis [14]

Dual Diagnosis Is Not

Comorbidity/Co-Occurring Disorders

Co-Occurring/Comorbid Disorders	Dual Diagnosis
One disorder followed by another, or disorders occurring one after another sequentially	Each disorder occurs simultaneously
Neither disorder has been created or triggered by symptoms of the other	Can be created by symptoms of the other disorder
Sequential treatment not prioritising either disorder	Integrated and simultaneous mental health and substance abuse treatment

Substance Misuse Alone Vs Dual Diagnosis

Dual diagnosis is defined as the presence of a separate psychiatric disorder alongside substance misuse.

Whereas, substance misuse alone may lead to indicators of psychiatric complaints, but is not a standalone psychiatric disorder.

Complex Mental Health Diagnoses Vs Dual Diagnosis

Complex mental health diagnoses include:

Schizophrenia
Bipolar disorder
Post-traumatic stress disorder
Anorexia or bulimia
Personality disorders (e.g. multiple personality disorder, borderline personality disorder)

Whereas dual diagnosis is the presence of a mental health disorder and an alcohol or substance use disorder existing simultaneously.

Behavioural Health Diagnoses Vs Dual Diagnosis

A behavioural health disorder is produced by behavioural issues, such as:

Substance use disorder
Anorexia or bulimia
Gambling addiction
Sex addiction

Whereas, dual diagnoses as a mental illness, can be created by underlying brain chemistry, or genetic factors.

Attempts To Standardise Meaning

Attempts to standardise meaning of dual diagnosis have been unsuccessful, leading to distinctions in diagnostic criteria, including:

A severe mental health disorder and substance abuse
Any form of mental health disorder and drug or alcohol dependency

This lack of universally accepted definition has led to inconsistent care, as medical professionals do not have enough research available to substantiate the effectiveness of different treatments.

Establishing diagnostic criteria allows researchers to develop appropriate treatments for different varieties of dual diagnosis [15].

Definitions Change In Different Settings

Rehab Clinic

In a rehab setting, the meaning of dual diagnosis and co-occurring conditions are synonymous for the purpose of treatment.

Hospital

Hospitals primarily focus on the mental health condition and consider addictive disorders secondarily.

For example, treatment plans focus on:

How alcohol has been used to self-medicate symptoms of mental health challenges

Research Environment/Academic Papers

The lack of a standard academic definition has led to differing definitions of dual diagnosis being adopted, e.g.

Primarily a serious mental illness combined with secondary substance addiction [16]
Primarily alcohol abuse combined with one or more secondary psychiatric complaints [17]

Insurance Policies

Insurance policies deal with dual conditions as separate claims for mental illness and addiction issues [18].

Definitions Change In Different Locations

In Canada, dual diagnosis refers to the presence of a learning disability and a psychiatric disorder [19].

In the UK and other countries with nationalised healthcare, difficulties arise when accessing joined-up treatment for simultaneous psychiatric disorders and addiction due to a lack of funding and service availability.

Countries with diverse ethnic backgrounds experience:

Language barriers impacting patient's understanding of dual diagnoses
Religious or cultural stigma of addiction/mental conditions affects treatment accessibility
Different cultures are offended by personal questions and do not continue treatment [20]

Header	Patient Diagnosed in USA	Patient Diagnosed in UK
Definition Of Dual Diagnosis	Any form of mental health condition and combined alcohol or drug dependency	Acute mental health condition and combined drug dependency
Service Availability	Private treatment - joined-up care at a cost	NHS treatment - going to different specialists causes lack of continuity of care
Cultural Attitudes Towards Serious Mental Health Issues	Stigma endorses secret drinking and not getting treatment [21]	Public mental health campaigns reduce stigma and increase accessibility of treatment [22]
Long-Term Treatment Outcomes	12% receive integrated dual-diagnosis treatment [23]	50% receive integrated treatment [24]

Legislation & Regulation May Change How It's Defined

Differing regulations or oversight in policies can influence how dual diagnosis is defined due to:

Medical professionals using the ICPC-2 finding that having three appointments and physical testing causes oversight of recognised indicators of illness [25]
Alcohol or mental health problem scales used in regulations mis-identifying underlying issues
Whiteford et al (2015) state that neurological disorders (e.g. Parkinson's and epilepsy) are considered part of the global disease burden, and suggest more effective interventions, or future research support of preventative measures, are required [26]
The North American Nursing Diagnosis Association (NANDA) uses a nursing diagnosis that focuses on the physical response to illness that informs intervention; this may lead to polydrug use being considered the reason behind symptoms and not combined mental illness and substance addiction [27]

How Different Definitions Change Treatment Priorities

The meaning given to dual diagnosis changes:

Is Parkinson's or epilepsy included? Are all mental health co-occurring disorders included or just those considered severe?
How treatment is prioritised - whether mental health disorder or addiction is treated first
What aspects of treatment are available - e.g. secondary diagnosis of mental health disorders due to nursing diagnosis leads to longer waiting lists for treatment
Access to differing medication types, off-label prescriptions, or regimens - these may not be in line with specific medical professional's definition, and therefore not prescribed

Order And Sequence Of Treatment May Change

The order and sequence of treatment may change due to:

Initially using nursing diagnosis may cause medical professionals to miss underlying causes or the possibility of multiple diagnoses causing symptoms that are only noticed sequentially
Initially using the ICPC-2 to focus on physical tests for symptoms may miss psychological symptoms that alter diagnosis

Different Definitions Can Impact Patient Care Plans

Elements Of A Care Plan	Defined As Severe Mental Health Disorder And Substance Addiction	Defined As Any Mental Health Disorder And Alcohol Or Drug Dependency
Current lifestyle and history of abuse	May overlook less advanced mental health issues that affect addiction	Focuses on co-occurring symptoms of mental health conditions and addiction
Psychiatric care needs	May not consider link between less advanced mental disorders (e.g. anxiety and depression) and substance abuse when planning psychiatric care needs	Will consider the link between all mental disorders and alcohol and drug dependency to inform psychiatric care needs
Motivation/ actions taken to get into recovery	Differing diagnosis may indicate lack of motivation to enter rehab	Complex cases result in low motivation to seek help
Risk assessment	Misdiagnosis of dual diagnosis could cause risks to be unaccounted for	Considers risks to self and others when starting treatment

Impact Of Differing Definitions, On Patients' Lives

Header	Diagnosed Via DSM-5	Diagnosed Via ICD
Differing definition of dual diagnosis	Focused on classifying mental health problems, leading to a quick diagnosis	Classifies all forms of disorders, leading to a longer diagnosis/diagnosis of physical symptoms and not mental health
Family and social support	Correct social support can be in place when needed	Social support may not be relevant when needed due to longer diagnosis
Experience of stigma	Some feel stigmatised due to labelling mental health disorders	Using codes for symptoms and diagnoses to avoid stigma
Treatment by other medical professionals	Classification may not be understood by other medical professionals, disrupting treatment	Classification is understood by other medical professionals
Access to care and support	Immediate access to joined-up care	Can be delayed access due to more extended diagnosis
Self esteem and psychological impact of diagnosis affecting relationships with others	Labelling mental health disorders leads to lower self esteem and negative relationships with others	Inclusive view of health improves self esteem and encourages better relationships with family
Aftercare	Individualised aftercare plan using DSM-5 to track progress and adjust plan if needed	Aftercare plan is not as detailed and uses holistic approach

References

[1] Basu, D., and N. Gupta. “Management of ‘Dual Diagnosis’ Patients : Consensus, Controversies and Considerations.” Indian Journal of Psychiatry, vol. 42, no. 1, Medknow Publications, 2000, pp. 34–47. “The term ‘dual diagnosis’ denotes the coexistence of substance use disorder(s) and other, non-substance-use, psychiatric disorder.”
[2] Merikangas, K. R., and C. S. Gelernter. “Comorbidity for Alcoholism and Depression.” The Psychiatric Clinics of North America, vol. 13, no. 4, Dec. 1990, pp. 613–32. Accessed 13 Apr. 2023. “Patients with major psychiatric conditions and substance abuse often fall between the cracks in clinical settings because of administrative distinctions between substance abuse and mental health.”
[3] Woody, George. “The Challenge of Dual Diagnosis.” Alcohol Health and Research World, vol. 20, no. 2, 1996, pp. 76–80. “Because each dual disorder can aggravate the course of the other, both disorders must be treated if the patient is to have the best chance for a good outcome (Woody et al. 1995). The first step in treatment is to perform an accurate diagnosis.”
[4] Hegner, Richard E. “Dual Diagnoses: The Challenge of Serving People with Concurrent Mental Illness and Substance Abuse Problems.” PubMed, National Health Policy Forum, 1998. “Failure to detect AOD abuse in psychiatric settings can result in misdiagnosis; overtreatment of psychiatric syndromes with medications; neglect of appropriate interventions, such as detoxification, AOD education, and AOD abuse counseling; and inappropriate treatment planning.”
[5] Stop Insurance Denial. “Dual Diagnosis Denial.” Stop Insurance Denial Law Firm, 2020. Accessed 12 Dec. 2024. “or unreasonable delays. There are several reasons that could lead to the denial of your insurance claim. Some of these include: Your insurer believes that the treatment you received was not medically necessary; Claiming that your dual diagnosis coverage is not provided in their policy; Denial or delay in authorizing treatments such as specialist care or MRIs; Your insurer claims that the procedure you underwent was too experimental or investigational; Declaring pre-existing conditions.”
[6] Ries, Richard. Assessment and Treatment of Patients with Coexisting Mental Illness and Alcohol and Other Drug Abuse Treatment Improvement Protocol (TIP) Series 9. DHHS Publication No, 1994, pp. 95–3061. “The type, duration, and severity of these symptoms are usually related to the type, dose, and chronicity of the AOD use.”
[7] Public Health England. Better Care for People with Co-Occurring Mental Health and Alcohol/Drug Use Conditions a Guide for Commissioners and Service Providers. 2017.
[8] Hasin, Deborah S., et al. “DSM-5 Criteria for Substance Use Disorders: Recommendations and Rationale.” American Journal of Psychiatry, vol. 170, no. 8, Aug. 2013, pp. 834–51. “For DSM-5, combine abuse and dependence criteria into one disorder (Figure 1), with two additional changes indicated below.”
[9] Mclellan, A., et al. Addiction Severity Index - 5th Edition..
[10] NHS Blackpool Teaching Hospitals. Alcohol Withdrawal Assessment Scoring Guidelines.
[11] Dual Diagnosis Network. "Severity of Alcohol Dependence Questionnaire (SADQ-C)."
[12] Hobden, Karen, et al. Assessing Mental Health Concerns in Adults with Intellectual Disabilities a Guide to Existing Measures. “The Assessment of Dual Diagnosis (ADD) was developed by Matson & Bamburg (1998) to assess the full range of psychiatric disorders in adults with mild to moderate intellectual disabilities. Because it is administered to a caregiver who knows the target person well, the target person’s verbal ability is not an issue. The 79-item scale has 13 subscales organized according to DSM-IV diagnoses.”
[13] NHS East London. NHS Foundation Trust. "Dual Diagnosis Policy." Nov. 2018. "If diagnosis is difficult, agree a ‘working diagnosis’, in order to plan treatment."
[14] NHS Surrey and Borders Partnership. NHS Foundation Trust. "Dual Diagnosis of Mental Health and Learning Disability Policy." "The policy sets out the framework within which people with dual diagnosis of mental health and learning disabilities will receive appropriate access to support through a collaborative approach."
[15] Hryb, Kathyrn, et al. “A Call for Standardized Definition of Dual Diagnosis.” Psychiatry (Edgmont), vol. 4, no. 9, Matrix Medical Communications, 2019, pp. 15–16. "By standardizing this definition of dual diagnosis, dually diagnosed individuals will be identified universally by clinicians rather than by individual professional opinion."
[16] NICE. NATIONAL INSTITUTE for HEALTH and CARE EXCELLENCE Guideline Scope. 2016. “Other factors that are causing mental illness and substance misuse, including physical health problems. For the purpose of this guideline, dual diagnosis is defined as a severe mental illness combined with misuse of substances.”
[17] Sherin, Kevin, and Stacy Seikel. Dual Diagnosis - an Overview | ScienceDirect Topics. “Dual diagnosis is defined as alcohol dependency with one or more other psychiatric comorbidities.”
[18] Bupa UK. Addiction and Mental Health | Support | Bupa UK. “Our mental health support provides ongoing, around-the-clock support for a wealth of mental health conditions, such as anxiety, depression and addiction.”
[19] Lunsky, Yona, et al. Dual Diagnosis an Information Guide. “The term dual diagnosis is used to describe a situation where someone has both a developmental disability and a mental health problem.”
[20] SAMHSA. Substance Use Disorder Treatment for People with Co-Occurring Disorders UPDATED 2020 TREATMENT IMPROVEMENT PROTOCOL TIP 42. 2020. “These clients may be offended by too many probing, personal questions early in treatment and never return.”
[21] Barry, Colleen L., et al. “Stigma, Discrimination, Treatment Effectiveness, and Policy: Public Views about Drug Addiction and Mental Illness.” Psychiatric Services, vol. 65, no. 10, Oct. 2014, pp. 1269–72. “These findings indicate that the American public holds significantly more negative attitudes toward persons with drug addiction than toward those with mental illness, and these attitudes translate into lower support for policies to improve equity in insurance coverage or to increase government funding in support of better treatment rates and housing and job support options.”
[22] UK Parliament. “Mental Health Stigma.” UK Parliament, May 2015. “Since the campaign began in 2007, there are signs that public attitudes to mental health are becoming more favourable, with a lower proportion of survey respondents expressing fear of those with mental health problems; higher support for integrating people with mental illness into the community; and higher levels of tolerance and sympathy for those with mental health problems.”.
[23] Michael's House. “Recent Facts and Statistics on Dual Diagnosis.” Michael’s House, 19 Oct. 2022. “12 percent got the integrated Dual Diagnosis treatment that addresses both disorders and is necessary to make real progress.”
[24] Schulte, Sabrina, et al. “Treatment Approaches for Dual Diagnosis Clients in England.” Drug and Alcohol Review, vol. 27, no. 6, Nov. 2008, pp. 650–58. “However, fewer than 50% of services reported assessing clients for both problem areas. Regarding specific treatment approaches.”
[25] WONCA World Organization of Family Doctors. World Organization of Family Doctors International Classification of Primary Care. “Sample of ICPC-2 Chart.”
[26] Whiteford, Harvey A., et al. “The Global Burden of Mental, Neurological and Substance Use Disorders: An Analysis from the Global Burden of Disease Study 2010.” PLOS ONE, edited by Gianluigi Forloni, vol. 10, no. 2, Feb. 2015, p. e0116820. “Mental, neurological and substance use disorders contribute to a significant proportion of disease burden. Health systems can respond by implementing established, cost effective interventions, or by supporting the research necessary to develop better prevention and treatment options.”
[27] Lukey, Alex. “2023 Nursing Diagnosis Guide: List, Types, Tutorial & Examples.” NurseTogether, 31 Jan. 2023. “There are also differences in each type of diagnosis. For example, medical diagnoses focus on the disease or pathology that affects the patient. In contrast, nursing diagnoses concentrate on the patient’s response to the illness or life circumstance, which can be either a physiological or psychological response.”

About the author

Harriet Garfoot

Harriet Garfoot BA, MA has an Undergraduate degree in Education Studies and English, and a Master's degree in English Literature, from Bishop Grosseteste University. Harriet writes on stress & mental health, and is a member of the Burney Society. Content reviewed by Laura Morris (Clinical Lead).

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Last Updated: October 30, 2025