As I’ve mourned my parents, I’ve been struck by how many stories I’ve heard about husbands and wives dying soon after their spouses. One of my high school teachers lost both parents within a year; so did a journalist friend in Los Angeles. My rabbi told me his parents died only months apart.

My mom buried both of her parents within the same week in April 1979, when I was 5. My zaydee died first, unable to fathom life without his wife, who lay dying in the hospital. My bubbe died during his funeral two days later.

I wondered whether there was more to this than coincidence, and sure enough, there’s a well-documented “widowhood effect.” Those who lose a spouse are about 40 percent more likely to die within six months than those with living spouses. The effect has been found in a host of countries, across a range of ages, in widows and in widowers — though men are more likely to die soon after losing spouses than women are.

S.V. Subramanian, a professor of population health and geography at Harvard University, co-wrote a review published in 2011 that looked at more than a dozen studies on the effect. “We never say that grief is a disease,” he told me. “But what some of this research is showing is that at older ages, grief can make you more vulnerable to mortality.”