It’s a top-10 list that helps explain where hundreds of billions of health-care dollars are spent by medical condition in the United States. Published Wednesday in Health Affairs based on federal data, the list holds some surprises — and signals some of the challenges ahead as this country continues to age.

Number one in the lineup is mental disorders, with a whopping $201 billion in estimated costs in 2013. Trailing far behind in second place are heart conditions, at $147 billion, then trauma, at $143 billion. Cancer costs come in fourth and diabetes a distant eighth.

The populations included for the calculations included non-institutionalized civilians, nursing home residents, long-term patients in psychiatric hospitals, prisoners and active-duty military. More than 40 percent of the total was spent on the institutionalized, noted author Charles Roehrig of the Center for Sustainable Health Spending at Altarum Institute in Michigan.

The good news, according to Roehrig’s report, was the low rate of growth in 2013 spending on heart problems, strokes and other cerebrovascular conditions. Age-adjusted death rates have been declining for these, the report said, probably because of decreases in smoking and “other lifestyle improvements.”

That positive, however, came with a very large caveat:

“A look ahead suggests that reductions in deaths from heart conditions and cerebrovascular disease are likely to drive spending on mental disorders even higher, as more people survive to older ages — when mental disorders, such as dementia, become more prevalent.”

The report also tallied the top 10 conditions with the sharpest increases in personal health spending from 1996-2013. It is a very different list.

Although mental disorders cover a wide range of illnesses, including schizophrenia,  postpartum depression and anxiety, as a category, during those years, they didn't rank high on the increased-spending list, which was led by such conditions as liver disease, diabetes and back problems. The rise in personal health spending for mental disorders, in fact, was just below average, at 5.6 percent. Nearly all the conditions listed in this top-10 tally relate to obesity.

Roehrig doesn’t blame greater disease prevalence for the growth in spending as much as the “introduction of expensive new treatments that reached increasingly larger segments of the affected population.” He points to Lipitor, a statin introduced in 1996 to control cholesterol, as a prime example.

“Between 2000 and 2012, the number of people being treated for [high cholesterol] roughly doubled,” Roehrig wrote, “despite only a modest increase in actual prevalence.”