As many as one in four students at some elite U.S. colleges are now classified as disabled, largely because of mental-health issues such as depression or anxiety, entitling them to a widening array of special accommodations like longer time to take exams.

Under federal law, students can be considered disabled if they have a note from a doctor. That label requires schools to offer accommodations depending on the student’s needs. A blind student, for example, would have access to specialized software or a reader for an exam.

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