Does ADHD ever show up as chronic overthinking?

Yes, and it surprises many people. ADHD is not just distraction. It can also involve mental hyperactivity. Some people do not look scattered outwardly but experience constant internal chatter, replaying conversations, analyzing small decisions, or spiraling on minor details. Executive dysfunction makes it harder to filter thoughts or shift attention away from unhelpful loops. There is also often anxiety overlap, which amplifies overthinking. Clinically, we look at whether the rumination is driven by fear and worry, or by difficulty disengaging the brain. ADHD treatment can sometimes reduce overthinking by improving cognitive control and mental flexibility. You are not imagining it. ADHD can absolutely live in the mind as much as in behavior.