In higher amounts, caffeine can lead to which of the following effects?

Caffeine, particularly when consumed in larger quantities, has a well-established physiological impact, one of which is the increase in plasma levels of epinephrine. This catecholamine, also known as adrenaline, is released from the adrenal medulla in response to stress or stimulation. Caffeine stimulates the central nervous system, leading to heightened alertness and a state of arousal, which in turn prompts the adrenal glands to secrete more epinephrine. The increase in epinephrine can enhance physical performance by improving cardiovascular function, increasing blood flow to muscles, and mobilizing energy stores.

In contrast, other listed effects do not align with the expected outcomes of high caffeine intake. For example, while caffeine may have complex interactions with blood pressure, it typically does not lead to a reduction; rather, it can cause an increase in certain circumstances. Increased plasma levels of cortisol, another stress hormone, could occur but are not as directly associated with caffeine consumption as epinephrine. Finally, caffeine is known for stimulating brain activity rather than inhibiting it, enhancing alertness and cognitive functions, which contradicts the idea of brain activity inhibition.