Yes, the guayusa in Brain Upgrade does contain caffeine. It's a naturally caffeinated leaf from the Amazon rainforest, traditionally brewed into a tea by Indigenous peoples of Ecuador and surrounding areas.
Here's a quick breakdown:
Caffeine content is similar to or slightly less than a cup of coffee, but more than green tea.
Other compounds: Guayusa also contains theobromine (like in chocolate), triterpenoids & polyphenols (anti-oxidants), and L-theanine, which may help smooth out the energy boost and reduce the jittery feeling often associated with coffee.