Use of health services for mental illness:Background and resources
A resource to help readers understand and use health services data for mental illness from the Canadian Chronic Disease Surveillance System.
- Last updated: 2026-04-14
Practical guidance to help users understand and report on the 'use of health services' measures for mental illness.
On this page
About mental illness
Mental illnesses are clinically diagnosable chronic conditions. They involve changes in a person's thinking, mood, behaviour, or a combination of theseFootnote 1. These changes within an individual can lead to their distress and affect their ability to function at work, school, in relationships, and during daily activities. Mental illnesses include a wide range of conditions such as:
- anxiety disorders
- eating disorders
- mood disorders
- post-traumatic stress disorder
- schizophrenia
- substance use disorders
The causes of mental illness are complex and not fully understood. However, research suggests that these factors can increase the likelihood of developing a mental illnessFootnote 2,Footnote 3,Footnote 4:
- genetics
- stressful or traumatic life events
- early life adversity
- socioeconomic conditions
Early recognition and timely care-seeking are important because they help individuals access supports, manage symptoms and improve quality of life.
Diagnosis
Diagnosing mental illnesses can be challenging. Most conditions do not have biological or physical markers that can be tested. Many possible diagnoses also have symptoms that overlap. A diagnosis is based on the individual's self-reported symptoms and the signs observed by clinicians or, in some cases, by family members.
Clinicians judge symptoms against recognized diagnostic criteriaFootnote 1. These diagnostic criteria represent the best available clinical descriptions of mental illnesses. Criteria help clinicians recognize and distinguish between conditionsFootnote 1. Diagnostic criteria, and their diagnostic codes, have evolved over time. Criteria continue to change as we learn more about the causes (etiology) and presentation of different conditions.
Interpretations of symptoms can vary, and symptoms may change over time. Because of this, it is common for someone to receive more than one diagnosis before the most accurate one is determined. Many individuals also receive more than one diagnosis because they meet criteria for more than one mental illness (referred to as comorbidity).
Surveillance
Because diagnosis can be complex, it is challenging to monitor mental illness in Canada. Symptoms can vary greatly in duration and intensity. Some individuals may also go for long periods without seeking or requiring care. Despite these challenges, surveillance is essential to understand how mental illness impacts people in Canada.
The Public Health Agency of Canada (PHAC) conducts national surveillance of mental illness through the Canadian Chronic Disease Surveillance System (CCDSS). The CCDSS is a collaborative network of provincial and territorial surveillance systems. It uses linked administrative health data to track over 20 chronic diseases and conditions. These linked data come from physician claims (often from family physicians) and hospitalization data.
The system currently publishes data on four key measures related to mental illness:
- Use of health services for mental illness and alcohol or drug induced mental health disorders (annual)
- Use of health services for mood and anxiety disorders (annual)
- Use of health services for schizophrenia (annual)
- Prevalence, incidence, and all-cause mortality for schizophrenia (lifetime)Footnote 5
This resource focuses on the first three that measure use of health services. These measure annual healthcare contacts, which is the proportion of people who use at least one health service for a mental illness in a given year. These three measures are not lifetime prevalence (the proportion of people who have ever had a mental illness). The lifetime schizophrenia measure does reflect lifetime prevalence which is supported by a validation studyFootnote 5.
These measures were developed considering the challenges in diagnoses and the value of administrative data for measuring healthcare useFootnote 6. Because these measures are unique, they may be difficult to understand and report. More details can be found in How to report data.
For more information on how these measures were developed, visit Technical notes.
Resources
- General information: Mental health and wellness
- Information on available supports: About mental illness
- For healthcare providers: Treating Conditions and Disorders | CAMH
Explore PHAC products using CCDSS 'use of health services' indicators for mental illness:
Acknowledgement
This work was made possible through collaboration between the Public Health Agency of Canada (PHAC) and all Canadian provincial and territorial governments, and expert contribution from the CCDSS mental illness working group. This site was developed by PHAC; no endorsement by the provinces and territories is intended.
Suggested citation
Use of health services for mental illness. A resource to help readers understand and use health services data for mental illness from the Canadian Chronic Disease Surveillance System. Public Health Agency of Canada, Centre for Surveillance and Applied Research. 2026.
References
- Footnote 1
-
American Psychiatric Association, DSM-5 Task Force. (2013). Diagnostic and statistical manual of mental disorders: DSM-5™ (5th ed.). American Psychiatric Publishing, Inc. https://psychiatryonline.org/doi/epub/10.1176/appi.books.9780890425596 (Retrieved November 2025)
- Footnote 2
-
Uher R, Zwicker A. Etiology in psychiatry: embracing the reality of poly‐gene‐environmental causation of mental illness. World psychiatry. 2017 Jun;16(2):121-9.
- Footnote 3
-
Öngür D, Paulus MP. Embracing complexity in psychiatry—from reductionistic to systems approaches. The Lancet Psychiatry. 2025 Mar 1;12(3):220-7.
- Footnote 4
-
Astorino MF, Calabrò M, Infortuna C, Muscatello MR, Briuglia S, Cicero N, Fabbri C, Serretti A, Crisafulli C. The Multifaceted Etiology of Mental Disorders With a Focus on Trace Elements, a Review of Recent Literature. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics. 2025 Jul 14:e33045.
- Footnote 5
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Kurdyak, P., Lin, E., Green, D. and Vigod, S., 2015. Validation of a population-based algorithm to detect chronic psychotic illness. The Canadian Journal of Psychiatry, 60(8), pp.362-368.
- Footnote 6
-
Public Health Agency of Canada. Report from the Canadian Chronic Disease Surveillance System: Mental illness in Canada, 2015. Ottawa (ON): Government of Canada; 2015.
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