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.
The Speaker of the House is a powerful position. The House Speaker is both the presiding officer of the House of Representatives and the leader of the majority party. The Speaker is also second to the Vice-President of the United States in the line of succession to the Presidency.