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 Majority Leader customarily serves as the chief representative of their party in the Senate, and sometimes even in all of Congress if the House of Representatives and thus the office of Speaker of the House is controlled by the opposition party.