ADHD can be commonly found in children and young people, however how common it is can be debated. Even though ADHD is well-known, there are studies that show that there are various groups in society that are underdiagnosed such as:
Underdiagnosis In Older Age Groups
Underdiagnosis of ADHD subtypes
Gender differences and underdiagnosis
Sigler, E., 2021. ADHD Looks Different in Women. Here's How — and Why.. [online] ADDitude. Available at: <https://www.additudemag.com/add-in-women/> [Accessed 8 December 2021].
van Vliet, A., 2021. ADHD. [online] Thisisgendered.org. Available at: <https://thisisgendered.org/entry/adhd/> [Accessed 8 December 2021].