Symptoms of significant brain atrophy include progressive cognitive impairment involving multiple cognitive functions, otherwise known as dementia, seizures and aphasia, which is the disruption in the understanding or production of language or both.
The Senate majority leader has somewhat less official power than the Speaker of the House. This is because the vice president is technically the Senate's presiding officer, a ceremonial position that calls chiefly for casting a vote in the event of a tie.
Depends on what you mean with power. The Speaker of the House is the 3rd position in the Chain of Command after the VP. But that is not enough to force the Senate Majority Leader to vote a bill passed in the House.