Joelle is a 20-year-old college sophomore referred by student health services after failing three courses. She reports lifelong difficulty sustaining attention during lectures, chronic disorganization, and reliance on last-minute deadline pressure to complete assignments. Her mother, who accompanies her, says Joelle was "always a daydreamer" but maintained B grades through high school with extensive parental scaffolding: her mother organized her binder nightly, set alarms for assignments, and sat with her during homework. Her childhood pediatrician never raised concerns. Joelle asks whether she can receive an ADHD diagnosis if no one identified it in childhood.

Darius is an 8-year-old boy referred by his teacher for persistent inattention. She describes a cyclical pattern: he engages with instruction for about 20 to 30 seconds, then "zones out" with a blank stare, then snaps back briefly before drifting again. This cycle repeats throughout the day. He is not disruptive. His parents confirm the pattern at home during homework. He was diagnosed with ADHD-Combined Presentation six months ago and started methylphenidate ER 18 mg, with moderate improvement in overall attention but the cyclical pattern persists.

Miles is a 10-year-old boy diagnosed with ADHD-Combined Presentation two years ago. His parents bring a report from a commercial brain-imaging center that claims Miles's scan shows "ADHD brain patterns" and recommends a proprietary neurofeedback program costing $8,000. They want to know if this scan confirms his diagnosis and whether they should invest in the treatment.

Camille is a 32-year-old pregnant woman (28 weeks) presenting for a developmental consultation about her 6-year-old son Kai, who was diagnosed with ADHD-Combined Presentation at age 5. Camille smoked half a pack daily during her pregnancy with Kai and is tearful, saying she has read that smoking causes ADHD and feels she is responsible for his condition. She quit smoking before this pregnancy but is anxious about the new baby's risk.

A school psychologist refers Lina, a 9-year-old girl, for evaluation. The psychologist describes a child who is "always in a fog": sluggish processing speed, excessive daydreaming, drowsiness during morning instruction, and slow to respond when called on. Lina is not distractible in the way the psychologist sees in her students with ADHD. She does not fidget, lose things, or blurt out. Her standard ADHD rating scales are borderline. She is cooperative and pleasant but seems mentally "somewhere else."

Fatima is a 10-year-old girl brought in by her parents after her fourth-grade teacher reported persistent daydreaming and incomplete classwork. She was born at 29 weeks gestation (birth weight 1,180 grams) and spent six weeks in the NICU. Developmental milestones were met on time after discharge. Her teacher describes her as "a sweet, quiet girl who never causes trouble" but notes she frequently stares out the window, fails to turn in completed homework, and needs instructions repeated. Fatima has no hyperactivity, does not interrupt, and is well-liked by peers. Her mother reports increasing tearfulness about school, difficulty falling asleep, and recent stomachaches on school mornings. A school psychologist evaluated her at age 6 and described her as "cooperative and pleasant" with no concerns. Report cards have consistently noted "not working to potential."