A danger for working-age people with disabilities is that they become socially isolated, which can cause a further deterioration in their health and ability to function. A good example of this vicious cycle is people with severe arthritis. If joint pain makes walking more difficult, it can limit one’s ability to do things with friends or be out in public, which means more social isolation and less exercise to ease the pain’s disabling effects. A new Mathematica study connects this phenomenon to the sharp rise in the share of Social Security disability awards going to people with arthritis, back pain, and other musculoskeletal conditions. Between 1997 and 2017, there was a slight increase, to 13.4 percent, in the share of…