I encourage my children to play golf, baseball, and tennis, rather than football, soccer, or hockey. Current brain imaging research has shown that many chemicals are toxic to brain function. Alcohol, drugs of abuse, nicotine, much caffeine, and many medications decrease blood flow to the brain. When blood flow is decreased the brain cannot work efficiently. The temporal lobes are involved with memory and mood stability.
Caffeine constricts blood vessels and has been shown to decrease brain activity.
A little bit of caffeine probably doesn't hurt much. Unfortunately, many people use excessive amounts, such as 6 to 10 cups of coffee, tea, or sodas a day. It is hard to be your best when brain activity is diminished. Stay away substances known to be toxic or those that decrease brain activity. In a similar way, sleep deprivation also decreases brain activity and limits access to learning, memory, and concentration.