Ronna Borenstein of Suburban Hospital in Bethesda said Sunday evening that she could not comment on the 95-year-old Shriver's condition or say when he was admitted.
Shriver announced in 2003 that he had Alzheimer's disease. He served as the first Peace Corps director in the administration of his brother-in-law, President John Kennedy. He also was Democrat George McGovern's running mate in 1972.
Shriver's wife and Special Olympics Founder Eunice Kennedy Shriver died in 2009 at age 88. He is the father-in-law of former California Gov. Arnold Schwarzenegger, who is married to former NBC reporter Maria Shriver.