CHICAGO – For the first time in almost two decades the nation’s psychiatrists are changing the guidebook they use to diagnose mental disorders. Among the most controversial proposed changes: Dropping certain familiar terms such as Asperger’s syndrome and dyslexia and calling frequent, severe temper tantrums a mental illness.

The board of trustees for the American Psychiatric Association voted Saturday in suburban Washington, D.C., on scores of revisions that have been in the works for several years. Details will come in May when the group’s fifth diagnostic manual is published.

The trustees made the final decision on what proposals made the cut; recommendations came from experts in several task force groups assigned to evaluate different mental illnesses. Board members were tightlipped about the update, but its impact will be huge, affecting millions of children and adults worldwide.