Definition of Oppositional defiant disorder:

Oppositional defiant disorder is a pattern of disobedient, hostile, and defiant behavior toward authority figures.

Causes, incidence, and risk factors:

This disorder is more common in boys than in girls. Some studies have shown that it affects 20% of school-age children. However, most experts believe this figure is high due to changing definitions of normal childhood behavior, and possible racial, cultural, and gender biases.

This behavior typically starts by age 8. The cause of this disorder is unknown, and may be due to a combination of biology and parenting or environmental factors.