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Behavioural disorders: Signs and symptoms


What are the main symptoms of a behavioural disorder?

Symptoms depend on the type of behavioural disorder a child or teen is experiencing: 

Oppositional defiant disorder

The behaviour associated with oppositional defiant disorder leads to struggles at school, at home and in the community for the child or teen or for the people that they interact with.

ODD has a number of symptoms under the following three main categories:

  • anger or irritability
  • argumentative or defiant behaviour
  • spitefulness.

A child or teen with ODD must experience four symptoms from across these categories and demonstrate them with at least one person who is not a brother or sister.

Anger or irritability

A person with ODD may, for example:

  • lose their temper often
  • be frequently touchy or easily annoyed
  • be frequently angry and resentful.

Argumentative or defiant behaviour

A child or teen with ODD:

  • often argues with authority figures such as teachers, parents or other adults
  • refuses to follow rules or comply with authority figures
  • often sets out to deliberately annoy others
  • often blames others for their mistakes or misbehaviour.


A child or teen with ODD might demonstrate spitefulness on at least two occasions within the previous six months. If they felt betrayed or hurt, for example, their actions might focus on feeling better about themselves at another person’s expense rather than correcting the negative behaviour.

Conduct disorder

Conduct disorder is a pattern of behavioural and emotional problems that is beyond what is considered to be typical child or teenage behaviour. A child with conduct disorder usually shows little or no concern for the rights of others. Many also do not understand, or feel any guilt about, how their actions affect others.

The symptoms associated with conduct disorder fall into four categories:

  • aggression to people and animals
  • property damage
  • deception (lying)
  • intentionally breaking rules.

Aggression to people and animals

A person with conduct disorder can show aggression by, for example:

  • bullying, threatening or intimidating others
  • starting physical fights
  • being physically cruel to people or animals
  • mugging or otherwise stealing from a victim while confronting them
  • using a weapon to cause serious physical harm
  • forcing someone to engage in sexual activity.

Destruction of property

Someone with conduct disorder may, for example, deliberately destroy or set fire to property.

Deception, lying or stealing

For a child or teen with conduct disorder, deception, lying or stealing can include:

  • breaking into a building, house or car
  • lying to get what they want or avoid obligations
  • stealing items without confronting a victim (shoplifting).

Intentionally breaking rules

When someone has conduct disorder, they have little respect for rules set by others.As a result, it is not unusual for them to, for example:

  • stay out at night against parents’ wishes
  • run away from home
  • skip school.

What your child’s doctor can do for a behavioural disorder

Your child's doctor can help identify if your child’s behaviour is normal for their developmental stage, if they are acting out in response to another stressor in their life or if their behaviour indicates a behavioural disorder. When requested, your child’s doctor will be able to help connect you with the most appropriate treatment for your child or teen.

Your doctor may sometimes need to refer your child for a more detailed assessment by a mental health professional. A thorough assessment can help you obtain a clear diagnosis and an appropriate treatment​ plan for your child or teen.

How behavioural disorders are diagnosed

Behavioural disorders are diagnosed through a thorough assessment by an experienced mental health professional, usually a psychiatrist or psychologist.

The professional will talk to you, your child or teen and, sometimes, your child’s school teachers. They will take your child’s medical history and family history into account and look at all factors that might contribute to your child’s behaviour, such as:

  • any other mental health problems
  • learning difficulties
  • family stressors.

It may take a few appointments for the psychiatrist or psychologist to gather this information. Once they do, they will decide if your child’s behaviour fits within the criteria for a diagnosis of a specific behavioural disorder. They may diagnose a behavioural disorder if your child’s challenging behaviours persist after other factors are addressed.

Key points

  • Symptoms of oppositional defiant disorder include anger or irritability, being argumentative or defiant and spitefulness.
  • Symptoms of conduct disorder include aggression to people and animals, property damage, deception and intentionally breaking rules.
  • Ask your child’s doctor to connect you with the right resources for assessment and treatment.
  • Behavioural disorders are diagnosed through a thorough assessment by an experienced mental health professional.

Further information

For more information on behavioural disorders, please see the following pages:

Behavioural disorders: Overview

Behavioural disorders: Treatment with psychotherapy and medications​

Behavioural disorders: How to help your child at home​​​

​Alice Charach, MD, MSc, FRCPC


S​tringaris, A. et al (2010). "What’s in a Disruptive Disorder? Temperamental Antecedents of Oppositional Defiant Disorder: Findings from the Avon Longitudinal Study." Journal of the American Academy of Child & Adolescent Psychiatry. 49 (5): 474-483. doi:10.1016/j.jaac.2010.01.021

Stringaris, A. & Goodman, R. (2009). "Three dimensions of oppositionality in youth." Journal of Child Psychology and Psychiatry. 50: 216-223. doi:10.1111/j.1469-7610.2008.01989.x​

Stringaris, A. & Goodman, R. (2009). "Longitudinal Outcome of Youth Oppositionality: Irritable, Headstrong, and Hurtful Behaviours Have Distinctive Predictions​." Journal of the American Academy of Child and Adolescent Psychiatry. 48 (4): 404-412. doi:10.1097/chi.0b013e3181984f30

Pardini, D. (2013). "Multiple Developmental Pathways to Conduct Disorder: Current Conceptualizations and Clinical Implications." Journal of the Canadian Academy of Child and Adolescent Psychiatry. 22 (1): 20-24.