IQ of the smartest people.
Stressed based puzzle solving is only useful in a small variety of fields, and makes you look like you have a problem if you're in a social setting... High Homocysteic Acid/Homocysteine (NMDA agonist/excitor) is also related to schizophrenia, and autism. It causes excitotoxity which kills brain cells due to over stimulation.
Better intelligence is understanding all possible variety of view points, and having only a little puzzle solving