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.
In the United States Senate, the majority leader is the chief spokesperson for the majority party, as the president of the Senate is ex officio the Vice-President of the United States, and the President pro tempore is a largely ceremonial position.