As my brother the psychiatrist pointed out the conventional stimulants prescribed for ADHD treatment can have wicked side effects and aren't necessarily effective. In moderate cases some in the field are trying nootropics plus cognitive stimulation therapy (of course that only works if natively there is sufficient functional cognitive hardware to stimulate and the patient wants to focus). Interesting footnote: the brother pointed out that Stephen Hawking is taking some similar cognitive enhancement concoction which includes a synthetic capillary growth stimulating chemical which goes by the name of vinpocetine. If a moderate ADHD patient, the combination of a nootropic (+ choline) and vinpocetine may be something worth testing.
For reference, a quick google of oxigenation and nootropics scares up:
Hah, neat, I had just ran into that chemical a few days ago in my own research, for similar reasons.
Right now I'm trying diosmin, under a parallel theory: that it protects, increases tone of, and stimulates growth of, lymphatic channels. (Amusingly enough, the main on-label use is for hemorrhoids.)
I picked this avenue of research since my own body seems to have a rather sucky lymphatic system: I constantly get fungal infections (but not bacterial/viral ones); I've had middle-ear infections several times in my life, once leading to labyrinthitis; I have a family history of lymphedema and varicose veins; and no matter how well I maintain my oral hygiene and stay hydrated, I still get dental carries and periodontal abscesses. (Also, oddly enough, all my hair grows really fast; and directly atop lymph nodes, I will get ingrown "compound" hairs (pili multigemni). Both sort of suggest an eccrine system trying to expel debris that isn't getting cleared any other way.)
So far I can at least say that it unplugs my sinuses (in a different way than a decongestant—gunk ends up in my throat, and my sinuses don't dry out), makes me experience heartburn for the first time since I was a child (probably a bile duct thing), and makes it actually painful to sit with my legs folded under me for more than a few minutes, whereas I used to be able to do that for hours (which was probably a bad thing with a high risk of DVT anyway.) So it's doing something.
The experiment I really want to try, though, is to combine the diosmin with N-acetylcholine (or any other metabolically-active glutathione precursor.) From what I understand, glutathione is used up by lymphatic processes (at least both of liver xenometabolism and mucus creation.) I expect, without NAC supplementation, it will appear that my body eventually "habituates" to the diosmin and stops doing anything useful.
Edit: one more bonus piece of anecdata—I've gone, on one week of diosmin, from a person who hates being too hot (to the point that I don't enjoy ever getting my face/chest wet in the shower; to the point that I hate drinking coffee/tea just because it's hot) but is fine in the cold (often not bothering to wear a sweater outside in Canadian winter)... to a person who can easily tolerate heat, and gets cold very easily. Very, very bizarre.
casual asides: a local retired GP where I once lived was into herbal supplements. For fungal disorders when all else failed he would frequently push high-concentrate oregano extract. Plus vinpocetine appears to be useful in treating tinnitus.
which suggests this may be something to research (Puritan's Pride online has it). And heat/cold tolerance seems circulation-focused. When growing up I was shuttled between northeast US and frequent sailing trips in SW Florida (where I am now ... snow sucks). Back then 30C seemed hot and sweaty. Now that's just a pleasant day in November. 10C seemed pleasant up north but now 10C in January here requires 2 or more layers. When the physiology stabilizes and acclimates the circulation adjusts.
For reference, a quick google of oxigenation and nootropics scares up:
http://nootriment.com/piracetam/