Researchers believe it is caused by neurotransmitter deficiencies which cause the part of the brain that controls distractibility, motor activity, and impulsivity to be underactive. Primary characteristic is distractibility. No significant symptoms of hyperactivity or impulsivity. No clinical signs of distractibility. Little research to indicate the utility of this subtype.
Primary characteristics are hyper-activity and impulsivity.
No clinical signs of distractibility. Little research to indicate the utility of this subtype. Symptom pattern may change with age. Approximately one-third of children outgrow the disorder by adolescence. Approximately one-half continue to display symptomology into adulthood.