ADHD is a prevalent, persistent and impairing psychiatric disorder, to a large degree explained by familial factors. As opposed to what was previously known, a substantial portion of children and adolescents diagnosed with ADHD will continue to experience impairing symptoms across their lifespan. However, the knowledge about ADHD in older adults (65+) is scarce and research has primarily focused on children and middle-aged adults. This case report highlights the importance of recognizing ADHD across the life span and describes »Nils«, who for over 40 years has received stimulant treatment for ADHD.