Which of the following is NOT a sign or symptom of a mental concussion?

In the context of a mental concussion, the signs and symptoms typically reflect a negative impact on cognitive function and alertness. A clouded mindset, drowsiness, and slowed reaction times are all indicative of the effects that a concussion can have on an individual's mental state. These symptoms are associated with cognitive impairment and decreased responsiveness, which are common after sustaining a concussion.

In contrast, increased energy does not align with these typical symptoms. Rather than reflecting a state of cognitive impairment, increased energy suggests heightened alertness and function, which contradicts the expected signs of a concussion. Thus, identifying increased energy as not being a sign or symptom of a mental concussion is accurate, as it indicates the opposite of the cognitive difficulties that concussed individuals usually experience.