There is research that finds that children with environmental allergies display decreased attention during allergic reaction episodes. There are also drags on attention/executive function that occur as side effects of medications for allergies and asthma. For most children, the net effect of med side effects is less severe than that of going unmedicated, especially on a bad day.
I didn't know this. What is interesting to me is that this would seem to be more evidence that issues with the immune system affect the nervous system and the brain. (And yet, mainstream medicine seems uninterested in the "side effects" of both the allergy, i.e. immune issue, and the treatment, and looking more toward root causes in cases of attention issues and so forth.)
I've been reading lately about certain immune problems that actually cause handwriting issues, possibly just the sort of motor issues indicated by a low Coding score. (Things that make you go "hmm...")
