Why not go further and also consider the cognitive implications of being ill, depressed, obese, stressed, parent of a newborn, or any other condition that could

Why not go further and also consider the cognitive implications of being ill, depressed, obese, stressed, parent of a newborn, or any other condition that could have short or long term implications on mental sharpness? I really hate when these ideas come of that effectively boil down to creating some kind of litmus test for who can be "trusted" to vote. We have an age limit, maybe the UK wants a lower limit, but at least that's a pretty simple and clear line to be drawn.