He says no one understood the importance of pursuing potentially life-saving treatments than the former first lady. She was buried Friday alongside her husband at the Ronald Reagan Presidential Library in California. President Ronald Reagan died of Alzheimer's in 2004.
Obama says in his weekly radio and Internet address that Nancy Reagan was one of the first people he contacted after he signed an order to resume federal stem cell research. It was a cause she advocated following her husband's diagnosis.
Obama says administration efforts to tailor health care to the individual and to better understand the human brain are possible because of her efforts.
She died Sunday at age 94.