Dan Shively had been a bank president who built floats for July Fourth parades in Cody, Wyoming, and adored fly-fishing with his sons. Jeffrey Dowd had been an auto mechanic who ran a dog rescue and hosted a Sunday blues radio show in Santa Fe. By the time their lives intersected at Canyon Creek Memory Care Community in Billings, Montana, both were deep in the grips of dementia and exhibiting some of the disease’s terrible traits. Shively had been wandering lost in his neighborhood, having outbursts at home, and leaving the gas stove on. Dowd previously had been hospitalized for being confused…