BERKELEY, Calif. — THE writing is on the chalkboard. Over the next few years, America can count on a major expansion of early childhood education. We embrace this trend, but as health policy researchers, we want to raise a major caveat: Unless we’re careful, today’s preschool bandwagon could lead straight to an epidemic of 4- and 5-year-olds wrongfully being told that they have attention deficit hyperactivity disorder.

Introducing millions of 3- to 5-year-olds to classrooms and preacademic demands means that many more distracted kids will undoubtedly catch the attention of their teachers. Sure, many children this age are already in preschool, but making the movement universal and embedding transitional-K programs in public schools is bound to increase the pressure. We’re all for high standards, but danger lurks.

The American Academy of Pediatrics now endorses the idea that the diagnosis of A.D.H.D. can and should begin at age 4, before problems accumulate. In fact, Adderall and other stimulants are approved for treatment of attentional issues in children as young as 3.

Early intervention for children with A.D.H.D. could provide great relief. Children who go untreated have major difficulties in school and with their peers, and they have higher-than-normal rates of accidents and physical injuries.