Patients often come into my office to be “tested for ADHD,” and I explain to them that the diagnosis depends on a thorough clinical interview. Nonetheless, rating scales can be useful.

To begin with, you have to specify whether you are thinking in terms of DSM-IV criteria or probable DSM-5 criteria. The major difference is that currently you have to establish that ADHD symptoms began before age seven, whereas DSM-5 is more lenient, requiring that they began by age 12.