Why do I shut down instead of asking for help?

Yes, this is very common, and research strongly supports what you are noticing. Large population studies show that a substantial proportion of adults with ADHD are diagnosed in adulthood rather than childhood. Epidemiologic data suggest that roughly 50 to 75 percent of adults who meet criteria for ADHD were not diagnosed as children. Many had symptoms all along, but they were missed, masked, or misattributed. There are several reasons for this. Earlier diagnostic models were based largely on hyperactive young boys, so people with predominantly inattentive symptoms, strong verbal skills, high intelligence, or good external structure were often overlooked. Many adults compensated through effort, anxiety, perfectionism, or supportive environments until those scaffolds disappeared. Transitions like university, parenthood, complex jobs, burnout, illness, or loss of routine are common points where symptoms become unmanageable and ADHD is finally recognized. Longitudinal studies also show that ADHD symptoms do not suddenly appear in adulthood. What changes is the mismatch between cognitive demands and available supports. When life requires more self direction, planning, and sustained executive control, previously compensated ADHD becomes visible. Clinically, late diagnosis is not a failure of insight. It reflects how well you adapted in systems that did not require sustained executive autonomy. You are very much not alone. Adult realization is the norm, not the exception.