Mental Disorders
Mental disorders are clinically significant disturbances in cognition, emotion regulation, or behaviour that reflect dysfunction in the psychological, biological, or developmental processes underlying mental functioning. The DSM-5-TR organizes mental disorders into approximately 20 diagnostic classes covering hundreds of specific conditions.
Overview
“Mental disorders” is the umbrella term for the clinical conditions defined in diagnostic classification systems such as the DSM-5-TR (American Psychiatric Association) and ICD-11 (World Health Organization). The DSM-5-TR defines a mental disorder as “a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behaviour that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning.”
The DSM-5-TR organizes mental disorders into approximately 20 diagnostic classes: neurodevelopmental disorders; schizophrenia spectrum and other psychotic disorders; bipolar and related disorders; depressive disorders; anxiety disorders; obsessive-compulsive and related disorders; trauma- and stressor-related disorders; dissociative disorders; somatic symptom and related disorders; feeding and eating disorders; elimination disorders; sleep-wake disorders; sexual dysfunctions; gender dysphoria; disruptive, impulse-control, and conduct disorders; substance-related and addictive disorders; neurocognitive disorders; personality disorders; paraphilic disorders; and other mental disorders.
Mental disorders are extraordinarily common. Approximately 1 in 5 Canadian adults experiences a mental disorder in any given year; lifetime prevalence is approximately 50%. Anxiety disorders are the most common (12-month prevalence ~12%), followed by mood disorders (~10%), substance use disorders (~5-7%), and ADHD (~5% of children, ~3% of adults).
Mental disorders are clinical conditions, not character flaws or moral failings. They have documented neurobiological, genetic, developmental, and environmental contributors. Effective evidence-based treatments exist for most conditions; outcomes are generally good with appropriate care, particularly when treatment is initiated early and sustained.
Despite this, only approximately 25-50% of people with diagnosable mental disorders receive specialty mental-health treatment in any given year. Stigma, structural barriers (cost, geography, wait times), low recognition, and limited capacity all contribute. Reducing the gap between treatable conditions and treatment access is a major Canadian public-health priority.
Signs and symptoms
- Persistent changes in mood — Sustained low mood, elevated mood, irritability, anxiety, or emotional dysregulation lasting weeks or longer.
- Sleep changes — Persistent difficulty falling or staying asleep, sleeping too much, or non-restorative sleep.
- Appetite or weight changes — Significant changes in appetite, eating patterns, or weight not explained by intentional dietary change or medical condition.
- Cognitive changes — Difficulty concentrating, remembering, making decisions, or persistent intrusive or unusual thoughts.
- Withdrawal from activities or relationships — Sustained reduction in engagement with previously enjoyed activities, friends, family, or work.
- Substance use changes — New or increased use of alcohol, drugs, food, or other substances/behaviors as coping strategies.
- Functional decline — Significant decline in academic, occupational, social, or self-care functioning.
- Suicidal thoughts or self-harm — Thoughts of death or suicide, plans, or self-injurious behaviour.
- Hallucinations or delusions — Sensory experiences without external source (hallucinations) or fixed false beliefs (delusions) — characteristic of psychotic disorders.
- Physical symptoms without medical explanation — Persistent physical symptoms (pain, fatigue, gastrointestinal, neurological) without identified medical cause.
Diagnostic context
The DSM-5-TR provides specific diagnostic criteria for each individual mental disorder. Diagnosis typically requires:
- Symptom criteria: presence of specified symptoms at specified frequency, intensity, and duration.
- Distress or impairment criterion: the symptoms cause clinically significant distress or impairment in functioning.
- Exclusion criteria: the symptoms are not better explained by another disorder, substance use, or medical condition.
Comprehensive psychiatric assessment includes:
- Clinical interview covering presenting concerns, history of present illness, psychiatric history, medical history, family history, social and developmental history, and substance use.
- Mental status examination.
- Validated screening and diagnostic instruments (PHQ-9, GAD-7, PCL-5, MDQ, ASRS, AUDIT, others as indicated).
- Medical evaluation to rule out medical contributors (thyroid, anemia, vitamin deficiency, substance effects, neurological conditions).
- Collateral information when available and appropriate.
Many mental disorders are highly comorbid; comprehensive assessment evaluates multiple potential conditions rather than seeking a single diagnosis. Differential diagnosis often requires longitudinal observation; some conditions (bipolar disorder, autism spectrum) require careful history-taking.
Causes and risk factors
Mental disorders develop through interaction of biological, psychological, and social factors:
Genetic factors: heritability ranges from approximately 30% (anxiety, depression) to 80%+ (schizophrenia, autism, bipolar disorder). Multiple common variants of small effect contribute to most conditions; rare variants of larger effect are documented for some.
Neurobiological factors: alterations in neurotransmitter systems (serotonin, dopamine, norepinephrine, GABA, glutamate), HPA axis, immune-inflammatory function, neuroplasticity, and structural and functional brain networks are documented across mental disorders, with disorder-specific patterns.
Developmental factors: childhood adversity (ACE exposure), attachment disruption, prenatal exposures (substances, maternal stress, infection), and early-childhood neurological insults all elevate risk across multiple disorders.
Psychological factors: personality traits (high neuroticism, low conscientiousness), cognitive patterns (rumination, catastrophizing, hostile attribution), attachment style, coping repertoire, and psychological resources all modify vulnerability.
Social and environmental factors: trauma exposure, chronic stress, social isolation, poverty, discrimination, immigration stress, and lack of social support all contribute. Structural factors (income inequality, housing precarity, access to healthcare) shape population-level mental health.
Comorbidity: mental disorders rarely occur in isolation. Anxiety and depression frequently co-occur; substance use disorders are common with most conditions; ADHD elevates risk for many other conditions; trauma history is associated with elevated risk across the diagnostic spectrum.
Cultural and contextual factors: presentation and recognition of mental disorders vary by culture; some conditions have culture-specific presentations (cultural-bound syndromes); stigma and help-seeking patterns are culturally shaped.
Typical treatments
Treatment varies substantially by specific condition; this section provides general principles applicable across mental disorders. See specialty pages for condition-specific information.
Psychotherapy: evidence-based modalities include Cognitive behavioural Therapy (CBT), Dialectical behaviour Therapy (DBT), Acceptance and Commitment Therapy (ACT), Eye Movement Desensitization and Reprocessing (EMDR), Interpersonal Psychotherapy (IPT), Mentalization-Based Treatment (MBT), and others. Specific approach is matched to condition, severity, and patient preferences.
Pharmacotherapy: SSRIs and SNRIs are first-line for most depressive and anxiety disorders. Mood stabilizers (lithium, valproate, lamotrigine) and atypical antipsychotics for bipolar disorder. Atypical antipsychotics for schizophrenia spectrum. Stimulants and alpha-2 agonists for ADHD. Benzodiazepines have limited role due to dependence risk. Pharmacotherapy is selected based on diagnosis, severity, side-effect profile, comorbidities, and patient preference.
Combined treatment: psychotherapy + pharmacotherapy generally outperforms either alone for moderate-to-severe presentations, particularly for depressive, anxiety, bipolar, and psychotic disorders.
Crisis intervention and safety planning when suicide risk, self-harm, or risk to others is present.
Levels of care: outpatient, intensive outpatient, partial hospitalization, residential, inpatient psychiatric hospitalization. Matched to severity, safety needs, and support resources.
Peer support and lived-experience services: peer specialists, recovery groups, and peer-led organizations are increasingly recognized as evidence-based components of care.
Lifestyle and complementary interventions: physical activity, sleep regulation, nutritional support, mindfulness, and social engagement all support recovery and are appropriate adjuncts to evidence-based treatment.
Neurostimulation: ECT for severe treatment-resistant depression and certain other conditions; rTMS for treatment-resistant depression; emerging evidence for other conditions and modalities (DBS, ketamine, psychedelic-assisted therapies).
Recovery-oriented care: contemporary mental-health care emphasizes recovery — meaningful improvement in symptoms, functioning, and quality of life — as the goal, supported by evidence-based treatment, peer support, social inclusion, and self-determination.
When to seek help
Professional support is indicated when:
- You are experiencing persistent changes in mood, sleep, appetite, energy, or thinking lasting two or more weeks.
- Symptoms are interfering with work, school, relationships, or daily functioning.
- You are using alcohol, drugs, food, or other behaviors as coping strategies.
- You are experiencing thoughts of suicide, self-harm, or harming others.
- You are experiencing hallucinations, unusual beliefs, or significant cognitive changes.
- Family or friends have expressed concern about changes they have noticed in you.
- Previous mental-health treatment has not produced sustained improvement.
- You have a known mental-health condition and are experiencing relapse or worsening symptoms.
If suicidal thoughts or thoughts of harming others are present, free 24-hour support is available across Canada at 9-8-8 (Suicide Crisis Helpline, call or text), 1-833-456-4566 (Talk Suicide Canada), or 811 (Health Link). For Indigenous-led culturally-competent crisis support: 1-855-242-3310 (Hope for Wellness Helpline, 24/7). For youth: 1-800-668-6868 (Kids Help Phone, call or text CONNECT to 686868).
Frequently asked questions
What is the difference between mental health and mental illness?
How common are mental disorders?
Are mental disorders caused by chemical imbalance?
Can mental disorders be cured?
Will I have to take medication forever?
How do I find a therapist or psychiatrist?
References
- American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.). APA.
- World Health Organization. (2022). International Classification of Diseases, Eleventh Revision (ICD-11).
- Mental Health Commission of Canada. (2012). Changing Directions, Changing Lives: The Mental Health Strategy for Canada.
- Pearson, C., Janz, T., & Ali, J. (2013). Mental and substance use disorders in Canada. Health at a Glance, Statistics Canada Catalogue no. 82-624-X.
- Insel, T. R. (2009). Translating scientific opportunity into public health impact: A strategic plan for research on mental illness. Archives of General Psychiatry, 66(2), 128–133.
Find the pattern behind what's been feeling hard
A few simple questions to help surface the concerns that may fit best.
Find Your PatternFind a Therapist by City
Browse therapy availability by city to see local and virtual options, explore services, and connect with a clinician who can serve your area.
Find a Therapist by Province
Browse therapy options by province to see which clinicians are available to work with clients in your region.
Trusted by Leading Psychology & Mental Health Organizations Across Canada
ShiftGrit Psychology & Counselling is professionally regulated, certified, and recognized by leading psychology and mental-health organizations across Canada. These associations reflect our commitment to ethical practice, clinical standards, and evidence-informed therapy through Identity-Level Therapy and Reconditioning.
Trusted By Alberta’s Leading Psychology & Mental Health Organizations
ShiftGrit Psychology & Counselling is professionally regulated, certified, and recognized by leading psychology and mental-health organizations across Alberta and Canada. These associations reflect our commitment to ethical practice, clinical standards, and evidence-informed therapy through Identity-Level Therapy and Reconditioning.
Regulated and affiliated across Alberta’s leading psychology, counselling, and mental-health organizations.
Regulated and affiliated across Canada’s leading psychology, counselling, and mental-health organizations.
