Can adults develop ADHD, or is it always childhood-onset?
DSM-5 requires that ADHD symptoms begin before age 12. True adult-onset ADHD — with no childhood symptoms whatsoever — is rare and scientifically controversial. However, adult diagnosis of previously unrecognised childhood ADHD is extremely common, particularly in women and people who are highly intelligent.
The reason so many adults are diagnosed late: intelligence and effort can compensate for ADHD symptoms through school and early career. When demands increase (having children, a demanding new job, losing structured support) the coping strategies stop being enough and symptoms become disabling for the first time — despite the underlying condition having been there since childhood.
Why women are often missed: Girls with ADHD are more likely to have the inattentive type (no hyperactivity), are more likely to develop compensatory strategies, and historically received less clinical attention than boys. Average age of ADHD diagnosis for women is significantly higher than for men.
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DSM-5 requires onset before age 12 for an ADHD diagnosis. Adults who are newly diagnosed typically had unrecognised childhood symptoms. True adult-onset ADHD without any childhood symptoms is controversial and rare — but adult diagnosis after years of compensation is very common.
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