The Journal of the American Medical Association, which found that spending on spine treatments in the United States totaled nearly $86 billion in 2005, a rise of 65 percent from 1997, after adjusting for inflation. Even so, the proportion of people with impaired function because of spine problems increased during the period, even after controlling for an aging population. It is not clear why more people appear to be suffering from back and neck pain. It could be because of rising obesity rates, researchers suggested.