A healthy 16 year old adolescent male arrives at your office with his parents, who are concerned about his several months' history of erratic behavior. At times he has a great deal more energy, decreased appetite, and less sleep requirement than usual; at other times he sleeps incessantly and is lethargic. He is doing poorly in school. Last evening he appeared flushed and agitated, he had dilated pupils, and he complained "people were out to get him." The family notes that he has been skipping school occasionally, and they reluctantly report that he was arrested for burglary 2 weeks previously. You know he is in good health and he previously has been an excellent student. Today he appears normal.
Drug abuse (probably cocaine or possibly amphetamines)