Fourth Edition, September 2011

How common are they?
Disruptive behaviour disorders appear to be more common in boys than in girls, and they are more com-
mon in urban than in rural areas. It is diffi
cult for everyone to agree on how to measure behaviour prob-
lems, but between 5% and 15% of school-aged children have Oppositional Defi ant Disorder (ODD). A 
little over 4% of school-aged children are diagnosed with Conduct Disorder (CD).
How long do they last?
Behaviours that may signal the beginnings of ODD or CD can be identifi ed in preschoolers. Some children 
with ODD may eventually mature and gain better control of their symptoms, but some do not. Some may 
go on to develop CD. Children and adolescents with CD whose symptoms are not treated early are more 
likely to fail at school and have diffi
culty holding a job later in life. They are also more likely to commit 
crimes as young people and as adults.
Educational implications
Behaviour problems can disrupt the education of both the student with the problem, and of other stu-
dents in the classroom. Time spent out of the classroom because of behaviour problems may mean that 
a student misses instructional time.
Students who have trouble understanding or following the behavioural expectations in the class may 
also be having learning problems. Students who are struggling to understand their schoolwork may be 
frustrated and irritable, and have a lower tolerance for events that other students could ignore.
Conversely, these students may fi nd it more acceptable to ‘act out’ behaviourally, rather than acknow-
ledge that they don’t understand their schoolwork. This behaviour can irritate and alienate other students 
in the classroom, and make them less likely to provide help with the schoolwork.

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Making a Diff erence: An Educators’ Guide to Child and Youth Mental Health Problems
www.cymhin.ca
C 6
Behaviour Problems