This glossary provides some easy-to-understand definitions of commonly used mental health terms. As our site grows, we will continue to add terms to this glossary. If you don't see what you're looking for email us and we'll add it to our list.


Means that something (usually a disorder or a symptom) has come on quickly with a high degree of impact on a person.


Continuing to use a substance (for example alcohol or cocaine) for non-medical purposes despite wanting or trying to stop using it. Addictions have a negative impact on many areas of a person’s functioning in life. For example if a person’s substance use gets in the way of positive relationships with friends or family; success at school or work, it is interfering with their life. An addiction is characterized by: Abuse of a chemical; Behaviour of drug seeking and daily focus on the drug; Craving for the substance. People who are addicted will often experience withdrawal when they stop using a substance. But, withdrawal does not equal addiction. Withdrawal is a common physical response to quickly stopping a chemical that affects the brain.


The emotional experience that someone feels inside of themselves that can be recognized by others.  For example:  if you are looking/acting sad you can be recognized by someone else as you are feeling sad.


The fear and avoidance of situations in which one would feel unsafe if they began to experience a panic attack.


A fear and avoidance of situations where you might feel unsafe or unable to escape if you have a panic attack.


Limited communication and withdrawal from social interaction.


is responsible for emotional memories, responses to fear, emotions and arousal, as well as being involved in the release of hormones that prepare the body for action.


A word used to describe a lack of pleasure. Sometimes, people suffering with depression will experience anhedonia. For example the person doesn’t feel good when they are doing the things that normally make them feel good, such as playing a favourite game, swimming, watching movies, etc.  Anhedonia due to depression will get better once the depression has been successfully treated.

Anorexia Nervosa (commonly referred to as Anorexia)

A type of eating disorder. The main features that a person with Anorexia will experience are: refusing to maintain a minimally reasonable body weight, intense fear of gaining weight, and an unrealistic perception of their body image (for example: they think or feel that they are much larger or heavier than they actually are).. The word “anorexia” means loss of appetite but many youth with anorexia actually struggle to suppress their appetite.  Anorexia Nervosa can be effectively treated with various psychological and family focused therapies.

Anti-social Personality Disorder

A type of personality disorder. People with anti-social personality disorder have a long pattern of violating the rights of others. It begins in childhood or early adolescence and continues into adulthood. Other common terms for anti-social personality disorder are sociopath or psychopath. People with this personality disorder will often harm others without feeling remorse or guilt.

Antidepressant Medicine

A medicine that is usually used to treat the symptoms of depression or anxiety disorders. The antidepressant called “fluoxetine” is considered to be the most useful for helping in adolescent depression.  It usually takes 6 to 8 weeks for an antidepressant medicine to work in treating depression.


Medicines that are often used to help treat psychosis. Sometimes they can also be used to treat mood swings (such as severe depression or mania) or extreme behaviours (such as aggressive outbursts).  This can be confusing if a person is being treated with an antipsychotic medicine and does not have a psychosis.  If you are being treated with an antipsychotic medicine make sure you understand why it is being used and its risks and benefits.   Check out the “Evidence Based Medicine for Teens” .


Is a type of body signal, or group of sensations that are generally unpleasant. A person with anxiety experiences a variety of physical sensations that are linked with thoughts that make them feel apprehensive or fearful.   A person with anxiety will often also think that bad things may happen even when they are not likely to happen.  For example you may be thinking about your puppy falling and getting hurt when it is on the bed and this makes you feel anxious. Anxiety is normal and everyone experiences it. It is a signal that we need to adapt to life’s challenges by learning how to cope. When you have so much anxiety that it interferes with your normal routine or many parts of your life such as, school, work, recreation, friends or family—that is when it becomes a problem and maybe even a disorder. Typical sensations of anxiety include: worry; ruminations; “butterflies”; twitchiness; restlessness; muscle tension; headaches; dry mouth; feeling as if air is not coming into your lungs; etc.

Anxiety Disorders

A group of common mental disorders. People with an Anxiety Disorder will experience things like mental and physical tension about their surroundings, apprehension (negative expectations) about the future, and will have unrealistic fears (see anxiety). It is the amount and intensity of the anxiety sensations and how they interfere with life that makes them Disorders. Some common types of Anxiety Disorders are; Social Anxiety Disorder; Panic Disorders; Separation Anxiety Disorder; Generalized Anxiety Disorder.  Anxiety Disorders can be effectively treated with psychological therapies or medications.

Asperger Syndrome

Often considered to be a developmental disorder that can usually be diagnosed prior to adolescence. People with Asperger’s experience repetitive and restrictive behaviours and interests that may lead to impaired functioning at work and socially.  Asperger’s is considered one of the several disorders on the Autism Spectrum and is unique because there is no significant delay in language development. Many people with Asperger’s live full and productive lives without any (or minimal) treatment.  Recent research is challenging the idea that Asperger’s is a disorder but much more study of this is needed.

Attention Deficit Disorder (ADD)

A term used in the past to diagnose what is now called ADHD (see attention deficit hyper-activity disorder).

Attention Deficit Hyper-Activity Disorder (ADHD)

A mental disorder that is usually lifelong and associated with a delay in how the brain matures and how it processes information. People with ADHD usually have varying degrees of difficulty paying attention, being impulsive, and being over active which causes problems at home, in school, and in social situations.  There are three kinds of ADHD: Inattentive Type, Hyperactive-impulsive Type and Combined Type. People with Inattentive Type mostly have problems paying close attention to things or being able to pay attention for long periods of time, so it is harder for them to focus on schoolwork or things that take a lot of concentration for more than a short period of time People with Hyperactive-Impulsive means being on the go and are often not very good about thinking things through before they act. People with Combined Type have problems with inattention and hyperactivity/impulsivity. ADHD can be treated effectively with medication and behavioural techniques. About 1/3 of young people with ADHD may have a learning disability, so anyone who is diagnosed with ADHD should have special learning tests done.

Atypical Antipsychotics

Newer types of medicines that help treat psychosis. Sometimes they can be used to treat mood swings (such as severe depression or mania) or extreme behaviours (such as aggressive outbursts).  See “Antipsychotics” above.

Autism Spectrum Disorder (ASD)

A life-long mental disorder in which the person suffers with significant abnormal development of social interaction, verbal and non-verbal communication. A person with Autism has trouble understanding the feelings of others (empathy) and usually does not understand many social norms (rules that tell us what is socially acceptable). Language difficulties range from the inability to speak to automatic sounding repetitive phrases to normal language that sounds formal and emotionless. People with Autism Disorder may also display repetitive behaviours (for example, continuous flapping of hands) and strong need to follow a precise daily schedule and routine. In Autism symptoms can vary from extremely severe to mild. Numerous treatments are available to help improve many of the symptoms of Autism but as yet there is no single best treatment for Autism.   The causes of Autism are complex and not well understood but the popular perception that vaccinations cause Autism is not correct.


Means having little or no motivation or drive to do things.  For example, not getting dressed or not wanting to go out with family or friends, this is not the same thing as “lazy”.


The long, fibre like part of a nerve cell (neuron) in the brain or spinal cord by which information is carried to other nerve cells.


are medications that are used to treat a number of different mental disorders – most commonly anxiety.  They can also be used to treat severe restlessness and agitation.  When properly used they can be very helpful.


This is where teens are using mobile devices to send text messages (SMS/txt) to a “bookie” to place bets.

Bipolar Disorder (manic depression)

is a mood disorder. People with Bipolar Disorder have experienced at least one full depressive episode and at least one manic episode. Most people with Bipolar Disorder have their first episode before age 25 and it is usually a depression. Bipolar Disorder can be effectively treated with medications and various psychological therapies.

Bipolar Disorder type 2 (hypo-manic depression)

is a mood disorder. People with Bipolar Disorder type 2 experience at least one full depressive episode and at least one hypo-manic episode. Hypo-manic episodes are similar to manic episodes but are not as severe. These episodes may last days to months. Bipolar Disorder type 2 can be effectively treated with medications and psychological therapies.

Blunted Affect

Blunted Affect: these individuals experience less sadness, joy or anger than most people

Borderline Personality Disorder (BPD)

is a personality disorder. People with borderline personality disorder have difficulty in regulating their emotions and can experience intense bouts of anger, depression, and anxiety that may last from hours to days or longer.  These bouts occur over and over again, often in response to minor life stressors or just on their own. People with BPD have unstable moods, stormy relationships, poor self-image, and self-harming behaviours which can lead to impulsive aggression, self-injury, risk taking and substance abuse.


is the center of: adaptation, exploration, procreation and civilization. It is the master control of you and your body. You are what your brain is. Your mind is what your brain does. The brain is made up many different parts that are all connected with each other. Here is a very brief overview of some of the parts and some of what they do.

Brain Stem

relays messages from the body to the rest of the brain (cerebrum & cerebellum) and vice versa. It also helps control many of the body’s vital functions, such as, breathing, digestion, heart rate, sleep and arousal.

Bulimia Nervosa

is an eating disorder often just called Bulimia characterized by excessive uncontrollable eating (binges of large amounts of food) over a short period of time, which is then followed by actions that try to get rid of the calories consumed (e.g. vomiting, laxative abuse, excessive exercise). This behaviour is repetitive and often followed by feelings of depression, self-disgust, and guilt. Bulimia can be effectively treated with psychological therapy or medications.

Calorie (also known as kilocalorie)

a unit of measurement to calculate heat expenditure or energy. It is often used to determine how much energy is in food or how much energy is used in physical activity. For example an apple may contain 80kcal of energy or a person may use 50kcal walking down stairs.


is important for coordinating movement, controlling balance and muscle tone.


is the largest part of the brain responsible for “higher functions” such as concentration, reason and abstract thinking.  It consists of two connected hemispheres (halves) that are divided into four lobes.


means something that is there most of the time for a long time.  Often used to describe a disorder that lasts for years or more.

Circadian Rhythm

The body’s biological clock. It regulates our sleep cycle.

Circadian Rhythm

is the body’s biological clock with a cycle of about 24 hours. It helps control our sleep and wake cycle as well as temperature and hormone variations.


is a setting where various health professionals work directly with patients.


an activity that takes place between a health provider and a patient (for example: diagnosis, treatments; etc.).

Clinical Trial

A research study that tests a treatment (drug or other therapy) for effectiveness, safety and tolerability.These studies involve at least two groups of participants – one group receives the experimental treatment, and the other group receives a previously established effective treatment, a placebo treatment or no treatment at all. Clinical trials are also called controlled clinical trials (CCTs) or randomized controlled trials (when patients are randomly assigned to treatment and comparison groups.


The way one thinks and processes thoughts and information. For an example, memory is a part of cognition.


the mental processes associated with thinking, learning, planning, memory etc.

Cognitive Behavioural Therapy

A form of psychotherapy (talk therapy), which is tailored to treat various mental illnesses. It focuses on changing the patient’s thoughts and behaviours to reverse the symptoms and increase the patient’s functioning.

Cognitive Behavioural Therapy

 is a form of psychotherapy (talk therapy), designed to help treat various mental disorders. It focuses on changing the persons’ thoughts and behaviours to help reverse the person’s symptoms and help increase the person’s functioning.

Cognitive Symptoms

are disruptions in normal thoughts. Some medical disorders can interfere with cognition. For example: negative thoughts in depression (“I am a useless person”) or delusions (see below) in psychosis (“The FBI is plotting against me”) or difficulties in planning or Cognitive Symptoms: pro

Community treatment

this means providing various kinds of treatments and services in the community instead of in the hospital.  For example: in the doctor’s office; in a health clinic or health center; in a school; etc.

Community Treatment Order

is a legal document that allows or stipulates that a person with a mental disorder will receive treatment while they live in the community.

Comorbidity (also known as dual diagnosis)

describes the presence of two disorders that may be associated in a person. For example someone who has been diagnosed with a Substance Abuse Disorder of Alcohol and Depression.

Completed Suicide

is the death of a person following a purposeful self-inflicted act with the intent to die. However, a more clear way of saying this is “die by suicide”.   It is important not to confuse self-harm with suicide attempts.


are repetitive behaviours used to suppress (push out of thought) obsessive thoughts or to follow strong urges. Some types of compulsions include: counting; checking; tapping; etc. While mild and occasional compulsions are common, severe and persistent compulsions can be part of Obsessive Compulsive Disorder.


A concussion is a brain injury that is caused by a blow to the head or body that leads to problems with brain function due to brain damage. It can occur without a loss of consciousness and can be caused by what seems to be a mild blow or bump. A concussion can occur in any sport or recreational activity, as a result of a fall or a collision or other mishap. A concussion can lead to many difficulties in thinking, emotions or behaviour and sometimes can lead to a mental disorder such as Major Depressive Disorder or Dysthymia.  A concussion requires proper medical treatment.  You can find out more about concussions in young people here:

Conduct Disorder (CD)

is a disruptive behaviour disorder. The individual with CD shows a persistent pattern of aggressive behaviours lasting over 6 months that are unacceptable to society. Examples include stealing, fighting, starting fires, etc.). Young people with CD often get into difficulty with the law.


means to give approval or permission to someone to do something. For example a patient must give consent to receive treatment or to be a participant in a research study.


A disorder of thought content or a belief that something has occurred or will occur that is not real or within reality. Persistent false beliefs that are odd, exaggerated and/or irrational. For instance, ‘my brain is being turned to glass by ray guns operated from outer space enemies’


is a disturbance of cognition where a person has fixed false beliefs that something has occurred or will occur that is not real. A common delusion is the belief that someone is trying to harm them, even though nobody is. Delusions are often associated with psychosis.


the specialized fibres that extend from a neuron’s cell body and receive messages from other neurons (nerve cells).


any substance (medication or drug) that slows down a person’s thinking and/or physical functioning. Examples include some pain killers and alcohol.


is a term used to describe a state of low mood or a mental disorder. This can be confusing because people may often feel depressed but will not have the mental disorder called Depression.  People with a Depression could be experiencing either Major Depressive Disorder or Dysthymic Disorder. The most common type of Depression as a mental disorder is a Major Depressive Disorder (MDD). A person with MDD feels very low /sad/depressed or irritable and also experiences: lack of interest; less pleasure; hopelessness; fatigue; sleep problems; loss of appetite; suicidal thoughts. MDD has a negative impact on a person’s life; home; family; school/work; friends etc. Depression can also be part of a Bipolar Disorder (see above). MDD can be effectively treated with psychological therapies or medications.

Depressive Episode

describes a period of depression in MDD or Bipolar Disorder. It includes at least 5 or more of these symptoms being present most of the time, mostly every day  for 2 or more weeks: depressed mood; a clear decrease in interest or pleasure in most or all (once enjoyable) activities; a significant weight gain or loss without dieting or loss of appetite; unable to get enough sleep or too much sleep (Insomnia or Hypersomnia); slow movements or purposeless movements from mental tension such as, nervousness or restlessness, which is observable by others (also known as psychomotor agitation or retardation); feeling tired or having less than a normal amount of energy; feeling worthless or a lot of inappropriate guilt; diminished ability to think or concentrate, or indecisiveness (have difficulties making decisions); recurrent (happening again and again) thoughts of death, suicidal ideation (thoughts and/or ideas about death or dying), suicide plan, or suicide attempt.


 is physical and psychological (emotional and cognitive) growth throughout life.


is a description that identifies a medical or mental disorder or illness. In North America a diagnosis is determined by the Diagnostic and Statistical Manual of Mental Disorders (DSM) and by the International Classification of Diseases (ICD).   A diagnosis is a medical act provided by doctors, psychologists and others trained in diagnosis.  A diagnosis is not a label.


 an abnormality in mental or physical health; disorder is often used as another name for illness.

Disorganized speech and behaviour

Disorganized speech and behaviour is often noticed when individuals make up words, put words together in random ways that aren’t comprehendible as sentences. Their behaviour may be all over the place, they are not productive at getting anything done.


Distress always has a causal event, functional abilities are only affected mildly, will disappear with a change in the environment, and professional intervention is not usually necessary.


is mental or physical suffering. Distress is a part of normal life. Distress is not a mental disorder.

Double Depression

 is a mental disorder which is characterized by the presence of both Major Depressive Disorder and a less severe depression known as Dysthymic Disorder in one individual.


is a diagnostic manual published by the American Psychiatry Association that names and describes mental disorders. It divides mental disorders into categories called diagnoses based on lists of criteria (signs and symptoms).  Its name is the Diagnostic and Statistical Manual (DSM) the IV-TR refers to the version of the manual as it is updated over time.

Dysthymic Disorder

 is a mood disorder. People with Dysthymic Disorder experience persistent low mood for two or more years (or one year for children) but experience fewer depressive symptoms than in Major Depressive Disorder. This low grade depression can result in many difficulties at home; school/work; with family; with friends. Dysthymia can be effectively treated with psychology therapies or medication.

Eating Disorders

are a group of mental disorders related to eating. People with (an) eating disorder(s) excessively control their eating, exercise and weight. These disorders include Bulimia, Anorexia Nervosa, Binge Eating Disorder, and Eating Disorder Not Otherwise Specified.  Eating disorders can be effectively treated using various psychological and medical treatments.

Electro Convulsive Therapy (ECT)

is a form of treatment for mental disorders in which improvements in the disorder are produced by the passage of an electric current through the brain. ETC is given with anaesthetic and is most often used to treat severe mood disorders.  Its name has the word convulsion in it which means “uncontrollable shaking”.  This used to occur in the past but does not happen now because the electric current is given while the person is under anaesthetic.


this word means a much exaggerated sense of happiness or joy.  In a mental disorder this can be found in Bipolar Disorder.


this is personality type where someone is very outgoing and sociable.  People with this personality feature are often called “extroverts”.

Flattened Affect

Flattened Affect: the expression of few emotions, which can include expressing the opposite emotion (ie. for instance laughing at death).

Frontal Lobe

is important in controlling movement, planning behaviour (actions), reasoning, emotions, and problem solving.

Functional Impairment

is a state in which a person is not functioning as they usually would or not functioning well in one or more area of life (i.e. family, friends, intimate relationships, work, school, etc.).

Functional Magnetic Resonance Imaging (fMRI)

this is a method for studying how the brain is working.  Pictures are taken of different changes that are created when blood flows through different parts of the brain.  They help us better understand how the brain works when it is healthy and when it is sick (such as with a mental disorder).

Generalized Anxiety Disorder

is a mental disorder which is characterized by excessive anxiety and worry about numerous possible events (not any single, specific event) that leads to problems with daily functioning. People with GAD worry all the time and experience many physical symptoms because of the worry (headaches; stomach aches; sore muscles; etc.). GAD can be effectively treated with psychological therapies or medications.

Genetic disposition

this describes the probability that a disorder may be due to genetic factors passed on from parents to their children.


 Having an exaggerated belief in one’s importance or abilities.


is having a highly exaggerated and unsubstantiated belief in your importance, ideas or abilities. Unrealistic amounts of grandiosity can be found in Mania and Hypomania.

Gray Matter

is the part of the brain that is dark in color. It is mostly made up of nerve cells (neurons).


is normal emotional suffering experienced by a person from a loss of a loved one (e.g. it is experienced when a family member dies). It is different from a depressive disorder.  Grief is not a mental disorder.


is a disturbance of how your brain perceived the world. A person with an hallucination experiences senses that aren’t real (i.e. sound, sight, smell, taste, or touch). For example, a person with psychosis is hallucinating if they hear voices that aren’t occurring in reality.


Involve seeing, hearing, smelling, feeling, tasting things that aren’t there.


is a state of physical, mental, social, and spiritual wellbeing and not just the absence of disease or infirmity. It includes mental health.

Health Care Professionals

are the trained professionals who help with the care of people who are sick or who help people and communities stay well. Examples include: doctors, nurses, psychiatrists, psychologists, occupational therapists, social workers, etc.


is involved in turning emotional information into memory, learning, and regulating (controlling) emotional responses.


is used to describe an a type of care that focuses on the whole person, which takes into account their physical and mental state as well as their social background rather than just treating the symptoms of an illness alone.


Chemicals that are important in affecting growth, development, mood, and metabolism.


are chemicals formed in one part of the body and carried to another body part or organ where they have an impact on how that part functions. They are important in growth, development, mood, and metabolism (food uptake and break down). For example, serotonin is a hormone in the brain that affects mood; growth hormone comes from the pituitary gland to many parts of the body and affects growth; testosterone affects sexual functioning; etc.


being kept or staying in a hospital as a patient for doctors and other health care professionals to decide on a diagnosis and implement a treatment plan for the patient.  Hospitalization for a mental disorder is usually used only if the disorder is severe or the person is in a crisis situation

Hypomanic Phase (hypomania)

is a milder form of a manic phase. It is usually a part of bipolar disorder. Hypomania can be effectively treated with medication and psychological therapies.


communicates with the limbic system to influence behaviour and emotions, controlling body functions such as temperature, sleep, appetite, sexual drive, stress reactions. Also helps control hormone release from the pituitary gland of the brain-endocrine system.


has the same meaning as disease. However, having an illness can mean you have one disease or multiple diseases.

Informed Consent

Participants are informed about all aspects of the study (purpose, procedure, risks, benefits, etc.) before deciding whether or not to participate in the study.


means to look inward, for a person to mostly focus on their inner selves and less on their social surroundings.  People that have this personality characteristic are often called “introverts”.

Involuntary Psychiatric Treatment Act (Nova Scotia)

 is a law that was passed by Nova Scotia in October 2005. The Act makes sure that those unable to make treatment decisions for themselves, due to their severe mental disorder, receive appropriate treatment. This act is used when someone with and due to a mental disorder:
a.  Has been or is threatening/attempting to be a danger to their self or others OR is likely to suffer serious physical harm or serious mental harm or both.
b. Does not have the ability to make decisions about their own care.
c. Requires care in a psychiatric facility and cannot be admitted voluntarily.
Every province in Canada has a similar law.

Involuntary status

is a term used to describe someone who has been admitted into a psychiatric facility (usually a hospital) against their will or without their consent, under the authority and protection of the law.

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