10% of the population of children and youth. Development that is not within normal ranges. Children and youth affected by mood and anxiety disorders. Related to chemical imbalance in the central nervous system. Associated with decreased levels of neurotransmitters such as serotonin. However, it is not simply a lack of serotonin. Children have a psychological toolkit (allows us to cope with trauma, either in a healthy or unhealthy way) Social support systems (psychologist will go discover what caused depression and help child work through it) Defined by marked changes in mood and energy. Bipolar is associated with fluctuation in neurotransmitters which affect the hypothalamus (central role in emotion regulation) Confusion, lack of coordination, frequent urination, dehydration, thyroid problems. This person is cycling every 24 hours. May develop after an individual experiences a traumatic event such as; Why does ptsd occur? sexual or physical assault witnessing a death natural disaster terrorist attack.