Hyperfocus:

Hyperfocus is an ADHD symptom of intense concentration for a long time on a single activity (fun, rewarding, or stimulating). ADHD’ers can become enter a flow state, tuning out everything else around them. Dopamine deficiency may be caused by changes in the brain’s frontal lobe, which controls reward, making it harder to manage and switch attention. ADHDers experience hyperfocus more frequently than others. They can manage hyperfocus, so they can still attend to things less absorbing (meetings, deadlines) through directed attention, which exerts effort to focus on or accept tasks with quieter, intrinsic rewards.