My 2C.. Our system doesn't provide the testing and data to make accurate, choices to build upon. We are at the mercy of over worked Drs, who look at basic tests, and often just have a minute to review at most. Our health is bound to the sheer luck of drawing a Dr who reads between the lines and can spot/sympathize/analyze our various issue(s).
My hypothesis is that there is too much variance in day to day life, activity, stress, food and liquid intake. In order to really test something I'd like to limit variables by using health apps for BP and HR, limiting diet by using something like Soylent for a month. That would establish the baseline test, then implement the change/drug/supplement, and test daily or weekly.
FWIW Yohimbe made me feel like shit. I would caution anyone looking at quick fixes without reading and setting up groundwork to accurately test yourself, even if its only anecdotal.
Why do I say we need to personally track things? There's a lot to learn.
Is your system starved for, or already flooded with the element you're about to consume? Is your system lacking a precursor? Is your system failing downstream to break something else down which is causing a cascading build up? Everybody up-regulates and down-regulates stimulants, catacholamines, etc at different rates. Are you able to break it down from it's required co-factors upstream or downstream? As for Yohimbe, our adrenergic receptors are part of the puzzle there.
Many people have metabolic enzymatic variances, deficiencies, to full blown impairment and we all have changing levels of receptors. Some elements cross the blood brain barrier, some don't. Some people can benefit from a supplement, or an enzyme but to others it's actually detrimental since it may block another pathway. Even commonly known Dopamine and Serotonin require various ingredients that may or may not be present in our systems such as dopamine beta hydroxylase, LDopa, BH4, etc. Various receptor density in any area can impact both the uptake and down regulation, while cascading their impact neighboring systems.
We as humans, are all very different on what works, and what doesn't. It sucks, and it's amazing.