What is a mental health disorder?

A mental health disorder is a medical condition defined by changes in a person’s thinking, mood or behavior that disrupt functioning and cause distress.

Approximately  one in five Canadians  will suffer from a mental health disorder at some point in their lives. By the age of 40, around  50%  of people will have lived with a mental health disorder at one time or another.

It is possible to live with a mental health disorder and have good mental health, but this can lead to suffering at times when, for example, treatment or social support is inadequate, or when symptoms are very intense or persist for a long time. Fortunately, support and treatment exist to reduce suffering, so that most people living with a mental health disorder can return to a healthy, satisfying life.

Beware of self-diagnosis

Evaluating and making a diagnosis is the fruit of a complex professional analysis that considers multiple factors: genetic, biological, environmental and experiential.

No single factor can cause a mental health disorder, and the manifestation of certain symptoms does not automatically point to a diagnosis of a mental health disorder.

Physicians, psychologists, and certain professionals authorized by their professional associations are the only ones officially empowered to do so, according to their field of expertise.

The main mental health disorders

If you’re concerned about yourself or a loved one, you’ll find summary information on some mental health disorders here. If you want to go further, talk to a professional.

Anxiety disorders

It’s natural to feel a certain level of stress or anxiety depending on the situations or events we encounter. For example, when we experience a major life change, an exam, a job interview, a sporting event, etc. This is the body’s normal reaction to a real or perceived threat, which generally disappears as soon as life returns to normal.

Anxiety, and potentially anxiety disorders , occur when anticipation is linked to a potential or non-existent threat. This state is accompanied by a feeling of apprehension, a state of vigilance, physical symptoms (palpitations, shortness of breath, sweating, trembling, dizziness, muscle tension, nausea, etc.) and automatic and/or intrusive thoughts (recurring thoughts, concern, anticipation of the worst, obsessions, etc.).

Although much more intense than a stress reaction, anxiety is not automatically considered a disorder. It can, however, become one if:

  • Concerns are excessive, ongoing and/or unrealistic.
  • It causes significant distress.
  • The intensity of the reaction exceeds the danger (of the situation).
  • It affects personal, school, or other functioning.

Do you recognize yourself in these situations? Find the descriptions of various anxiety disorders below.

Generalized anxiety disorder

People with generalized anxiety disorder (GAD) worry excessively and uncontrollably about everyday events and activities. They often experience unpleasant physical symptoms, including fatigue and muscle pain, and may also have difficulty sleeping and concentrating. To read a testimonial about this reality, read Laurie‘s story.

Specific phobia

Phobias are intense, persistent fears about specific places, situations, or things. Phobias can prevent you from going places you’d like to go or doing things you like to do. There are a number of different phobias that can be categorized:

  • Situational: concerns a specific situation, such as a phobia of airplanes, bridges, elevators, driving a car, etc.
  • Blood-injection-accident: includes any invasive medical procedure. This type of phobia is frequently associated with discomfort, which in some cases can be followed by fainting.
  • Linked to natural environment: phobia of thunderstorms, heights, storms, darkness, water, etc.
  • Animal-related: phobia of insects, dogs, snakes, rodents, spiders, etc.

People with a specific phobia have a persistent fear or anxiety of more than 6 months linked to the situation or object in question. They also have the following characteristics:

  • The situation or proximity of the object always triggers immediate fear or anxiety.
  • They actively avoid the situation or object.
  • Fear or anxiety out of proportion to actual danger (considering socio-cultural norms).
  • Fear, anxiety and/or avoidance cause significant distress that interferes with social or professional functioning.

Panic disorder

People living with a panic disorder experience unexpected and repeated panic attacks. A panic attack is a sudden surge of intense fear or discomfort, which peaks and subsides within a few minutes. A panic attack includes at least four of the following physical or psychological symptoms:

  • Rapid breathing or racing heart
  • Chest pain or discomfort
  • Sweating
  • Shaking or trembling
  • Shortness of breath or feeling of suffocation
  • Chills or hot flashes
  • Nausea or stomachache
  • Dizziness or vertigo
  • Feeling of unreality or detachment from self (derealization)
  • Sensations of numbness or tingling
  • Fear of losing control
  • Fear of dying

Panic attacks are quite common and having one doesn’t mean you have a panic disorder. They only become a disorder if you regularly worry about having another one, or if you’re afraid that something serious will happen as a result of a panic attack (such as going mad, losing control, or dying), or that it will induce major changes in behaviour to avoid another attack, such as avoiding exercise or certain places.  To read a testimonial about this reality, here are Kathleen’s and Simon‘s stories.


Agoraphobia is the fear of being outside the home, in a public place. It sometimes accompanies panic disorder in that the person with agoraphobia fears public places, often because they are afraid of not being able to get out easily or of having a panic attack there.  Read Marc-André’s story.

Social anxiety disorder (or social phobia)

Social anxiety is a fear associated with certain social activities or performance situations where the person may feel observed, embarrassed, humiliated, rejected, or concerned about the judgment of others. This fear becomes a disorder when it intensifies to the point of preventing the person from leading a normal life. The person may then no longer want to attend classes, avoid public places (e.g., shopping malls, gyms), stop talking in class, and so on. To read a testimonial on this reality, here’s Élise’s story.

Obsessive-compulsive disorder (OCD)

Obsessive-compulsive disorder (OCD) involves unwanted and disturbing thoughts, images or urges (obsessions) that take hold in the person’s mind and cause great anxiety or discomfort, to the point of wanting to reduce this feeling by adopting repetitive behaviours or mental acts (compulsions). To read a testimonial on this reality, here’s Émilie’s story.

Post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a reactive disorder that can occur following a traumatic event. An event is said to be “traumatic” when a person is confronted with death, the fear of dying, or when their physical integrity or that of another may have been threatened. The event must also provoke intense fear, helplessness, or horror.

A person who develops post-traumatic stress disorder:

  • Continually relives the traumatic scene in thought or nightmare (reliving symptoms).
  • Seeks to avoid, voluntarily or involuntarily, anything that might remotely remind them of the trauma (symptoms of avoidance and emotional numbing).
  • Is frequently alert (symptoms of hypervigilance) despite the absence of imminent danger.

Mood disorders

Mood is a state of mind dominated by an emotion, such as anger, sadness, or joy. Emotions can be pleasant or unpleasant, and sometimes painful. Usually, we feel in control of our emotions, but a person with a mood disorder experiences their emotions in a more intense, pervasive and long-lasting way than most people, impairing well-being and functioning.

Two of the most frequently observed mood disorders are described below: depression and bipolar disorder.


From time to time, everyone feels sad or gloomy. Problems, disappointments, and failures, can affect anyone’s mood. Most of the time, these feelings are temporary. But, when the gloomy mood is maintained for more than a few weeks and other symptoms appear, for example, lack of energy and isolation, this can be a sign of ‍depression. To read a testimonial on this reality, here’s Alexandre’s story.

There is no single cause of depression. It often develops due to a combination of factors, such as life events, biological factors (hormones, family history, genetics), lifestyle habits, illness, or ways of thinking that make a person more vulnerable. Here are the main physical and psychological symptoms of depression.

  • Fatigue
  • Lack of energy or restlessness
  • Sleep problems: sleeping too much or too little
  • Change in appetite: increase or decrease
  • Sexual changes: decrease or loss of interest
  • Discomfort: headaches, back or stomach pain
  • Great sadness (crying often)
  • Loss of interest in professional, social, and family settings
  • Feelings of guilt or failure
  • Decreased self-esteem
  • Difficulty concentrating or making decisions
  • Suicidal thoughts

Bipolar disorder

A person with bipolar disorder goes through periods when their mood is very different. These periods are called “episodes” of mania or depression and may be interspersed with times when their mood is “normal”. The frequency, duration and intensity of episodes can vary from person to person, but during them, it’s difficult to fulfill professional, family, and social obligations. To read a testimonial on this reality, here are the stories of Charles-Albert and Nawal.

An episode of mania can be recognized by the continuous presence, for at least one week, of several of the following signs and symptoms:

  • Feelings of intense happiness and pleasure or, on the contrary, excessive irritability.
  • Hyperactivity, restlessness, and boundless energy.
  • Inordinate self-esteem or ideas of grandeur.
  • Greater communications (the desire to talk).
  • Significant increase in the number of professional, school, social and family activities.
  • Decreased need to sleep.
  • Faster thinking.
  • Great distraction and difficulty concentrating.
  • Risky behaviour.

An episode of depression is characterized by the continuous presence, for at least two weeks, of several of the following signs and symptoms:

  • Great sadness and frequent crying.
  • Significant loss of interest in professional, social, and family activities.
  • Fatigue, lack of energy or restlessness.
  • Sleep problems (too much or too little sleep).
  • Decreased or increased appetite, which can lead to weight loss or gain.
  • Feelings of guilt or failure.
  • Decreased self-esteem.
  • Difficulty concentrating on a task.
  • Difficulty making decisions.
  • Suicidal thoughts.

Psychotics disorders

Psychotic disorders affect brain function by altering thoughts, beliefs, or perceptions. The period during which someone displays these symptoms is called a “psychotic episode”. For example, they may be convinced of being watched or followed, they may hear voices or feel that others are manipulating their thoughts. At this point, they have difficulty distinguishing between what they perceive and reality. A psychotic episode can come on gradually or suddenly and can take many different forms. Here are Sonia’s and Maximilien‘s stories.

Personality disorders

Personality is generally made up of a combination of traits, emotional reactions, attitudes, and behaviours that develop from birth to early adulthood, and then become relatively stable. For most people, having different personality traits enables them to present a wide range of reactions and coping mechanisms when faced with a stressful situation. Conversely, people with personnality disorders lack this flexibility and adaptability. Instead, they are rigid in their behaviour and reactions, even when a situation causes them suffering and negative effects in their lives.

There are several types of personality disorders.  Borderline personality disorder is the most well-known.

Borderline personality disorder

People living with borderline personality disorder (BPD) have an extreme or exaggerated fear of losing their ties with the people around them. They easily feel rejected or abandoned by others, which creates conflict in their social relationships. They therefore need their loved ones to reassure them that they are present and that their relationship is important. To read a testimonial on this reality, here’s Marie’s story.

To complete this clinical portrait, it seems relevant to bring some nuances with that of people living with narcissistic personality disorder (NPD). While people living with BPD experience the fear of abandonment, those living with NPD are more afraid of being humiliated and having their ego bruised. Generally speaking, no one likes to be crushed or rejected. What’s important to remember, however, is that those who suffer from BPD or NPD experience it more acutely, and their behaviour is guided by patterns of thinking such as: “I’m either merged with the other or I’m rejected (BPD)” or “I’m either superior to others or I’m less than nothing (NPD)”.

Eating disorders

Eating disorders are complex disorders characterized mainly by abnormal eating habits, intense fear of weight gain and preoccupation with body image. They have serious consequences for physical and mental health, and can disrupt family life, friendships, and everyday life.  The main types of eating disorders and associated behaviours are presented below.

Anorexia nervosa

Anorexia nervosa is a mental health disorder characterized by abrupt weight loss resulting from drastic dieting, fasting, induced vomiting, use of laxatives or excessive exercise. Anorexia nervosa is also associated with an intense fear of gaining weight and a distorted body image. To read a testimonial on this reality, read the stories of Marianne and Catherine.


Bulimia is a mental health disorder characterized by the presence of compulsive eating, followed by compensatory methods such as drastic dieting, fasting, induced vomiting, excessive exercise, and many others. Feelings of shame, guilt and disgust often follow these episodes. To read a testimonial on this reality, here’s Sophie’s story.

Bulimic hyperphagia

Binge eating disorder (or bulimic hyperphagia) is a mental health disorder characterized by the presence of compulsive eating, but without compensatory methods. Episodes of compulsive eating occur when, in a limited period of time, a much greater quantity of food is consumed than most people would consume in a similar period of time and under the same circumstances. They are often accompanied by a feeling of loss of control. Following this episode, the sufferer experiences guilt, shame, and disgust.

Unspecified eating disorders

Unspecified eating disorders include problems that do not precisely meet the criteria for specific eating disorders, such as anorexia nervosa, bulimia and binge eating. Examples include orthorexia and bigorexia. Despite this fact, people suffering from an unspecified eating disorder can also live with low self-esteem and an obsession with body image. They may count calories, institute crash diets, adopt overtraining habits and so on.


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American Psychiatric Association.  (2015) Diagnostic and Statistical Manual of Mental Disorders (DSM-5) 

Anorexie et boulimie Québec (2023) Troubles alimentaires

Association canadienne pour la santé mentale (2016) Les mythes au sujet des maladies mentales

Association canadienne pour la santé mentale (2022) Comprendre les troubles alimentaires et trouver de l’aide

Association canadienne pour la santé mentale (2022) Faits saillants

Gouvernement du Québec (2024) Mieux comprendre les troubles mentaux

Gouvernement du Québec (2021) Guide explicatif – Loi modifiant le Code des professions et d’autres dispositions législatives dans le domaine de la santé mentale et des relations humaines

Le manuel Merck (2002) Présentation des troubles de la personnalité


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Contribution to the article : Isabelle Queval, psychologist

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