Scientists reported yesterday that they were able to “see” pain on brain scans and, for the first time, measure its intensity and tell whether a drug was relieving it. Although the research is in its early stages, it opens the door to a host of possibilities.

Scans might be used someday to tell when pain is hurting a baby, someone with dementia or a paralyzed person unable to talk. The scans might lead to new, less addictive pain medicines, and even help verify disability claims.