The crux of brain health is the ability of a person to function well when 
performing daily activities, including work.

This includes functions such as making quality decisions, solving problems, enjoying emotional balance, and interacting successfully with others.

All of these functions are based on the ability to remember, understand, learn new things, process information, think strategically, and being innovative when solving problems. 

Note that brain health is not the function. Rather, brain health is the fact that your brain is in a good state that enables it to carry out those functions.