Sixty-nine percent of American adults monitor at least one aspect of their health, and 21% of those who do use some form of technology, such as a smartphone application or an electronic device, a Pew Research Center survey found. "It turns out that half of trackers say they are keeping track of progress just in their heads," said Susannah Fox of the center's Internet and American Life Project. Some apps transmit data to users' doctors, enabling them to spot early warning signs and adjust treatment accordingly, and many patients who have used digital health technology said it prompted conversations with their doctors.