The cause of ADHD is low dopamine levels. See the link: PET scans show depressed dopamine activity in ADHD. - Free Online Library
When you see it in a child, the reason for the low dopamine is usually genetically they just don't make enough of it. However, in a college aged female, the first thing I think of that causes low dopamine is not ADHD but low iron levels. Iron is the building block of red blood cells, and practically every woman who is actively having periods is low in it.
See the link, Evidence links cellular iron deficiency to restless legs syndrome
"Although this should result in more dopamine being made, in fact, the proper regulation of dopamine production is only possible with both active TH and adequate levels of iron."
TH is the enzyme that converts the amino acid tyrosine into dopamine. I have seen some women get a huge boost from tyrosine as well as iron.
A nutritionist told me that this type of iron does not cause the nausea that the more commonly prescribed iron sulfate does, Amazon.com: Thorne Research - Iron Picolinate (25 mg) - 60's: Health & Personal Care
, and I have yet to see anyone get nauseated or constipated on it.
If you want to check for low iron, your doctor would order a complete blood count to check for anemia and a ferritin level. The goal for treating low iron is a ferritin level > 50. However, I rarely check the labs anymore because I can't recall seeing any meunstrating women with a ferritin > 50.
Besides the ADHD symptoms, you often see depression, hair falling out, cold intolerance, easy bruising, fingernails cracking off, and restless leg syndrome with low iron. Low iron actually helps with pain tolerance though.
The Ritlain type drugs (amphetamines) do increase dopamine, so you probably do feel better on them, but I see medicine being used way too often for problems with low iron. The worst is the depression. The Prozac type drugs used actually interfere with platelet function and that make the meunstral bleeding more severe. Doctors are supposed to rule out medical causes for depression and ADHD, but IMO they rarely do.
I think that personality types are related to our body's neurochemistry, and I think dopamine is the key as to whether someone is S or N. So in theory, I think it is possible that an ESTP low in iron could change from an ESTP to an ENTP and back again once proper iron/dopamine levels are restored.