Since 2009, the elder Mr. Lee has been fighting a neurological disease that makes it difficult for him to walk, his daughter Lee Wei Ling, a neuroscientist, wrote in Singapore's Sunday Times in 2011.
News of the elder Mr. Lee's hospitalization coincided with a rare protest on Saturday by thousands of Singaporeans against a new government platform that keeps immigration as a key tool to mitigate the demographic impact from Singapore's low birthrates and aging population.