On Dec. 28, the world lost Debbie Reynolds, an entertainer best known for her work as one of the last performers from Hollywood’s “Golden Age,” with notable turns in such films as Singin’ in the Rain and Tammy and the Bachelor, and for her immense collection of Hollywood memorabilia.  

A day earlier, the world lost Carrie Fisher, a woman best known for her work in the Star Wars movies as Princess Leia and as a mental health advocate.

The tragedy, of course, was that they were mother and daughter.

Ms. Reynolds overcame much adversity in her life, triumphing over a succession of illnesses and scandals. She tried to stay strong for the people she loved.  

But losing her daughter, whom she had grown especially close to in the final decade of her life, proved too much. The loss of a child, no matter the age, leaves a void in one’s heart unlike any other.

At age 84, and frail, it is likely that the sadness and stress that Ms. Fisher’s death exerted on her contributed to the stroke that took Ms. Reynolds’ life.

“Broken heart syndrome” is a phrase given to a variety of medical phenomena, including stress cardiomyopathy and takotsubo cardiomyopathy, the latter of which (named for the Japanese term for “octopus trap”) is more likely to have affected Ms. Reynolds at that vulnerable time in her life.

Harvard Health Publications of Harvard Medical School describes takotsubo cardiomyopathy as “a weakening of the left ventricle, the heart’s main pumping chamber, usually as the result of severe emotional or physical stress, such as a sudden illness, the loss of a loved one, a serious accident, or a natural disaster such as an earthquake.”

The syndrome presents itself with symptoms similar to a heart attack, including shortness of breath and chest pain, and is often diagnosed as one, and problems with blood flow can lead to a stroke.

Dr. Suzanne Steinbaum, director of women’s heart health at Lenox Hill Hospital in New York, described takotsubo cardiomyopathy to The New York Times as “an overflow of stress hormones, and the heart can’t take it. It appears to be a massive heart attack, but the heart is literally stunned.”

The unforeseen loss of a child or spouse can take a significant toll on an individual’s health, both mentally and physically.

According to the American Heart Association, “Women are more likely than men to experience the sudden, intense chest pain—the reaction to a surge of stress hormones—that can be caused by an emotionally stressful event. It could be the death of a loved one or even a divorce, breakup or physical separation, betrayal or romantic rejection.”

Ms. Fisher and Ms. Reynolds had an extremely close relationship, documented most recently in a film that debuted on HBO last week. They grew to be more two best friends than a conventional parent and child.

Ms. Fisher’s death, caused by a heart attack on a flight to Los Angeles, hit her family extremely hard, putting them and the world in a state of mourning. Ms. Reynolds was making funeral arrangements for her daughter when she was stricken.

When the documentary about her and mother, Bright Lights, debuted at the Sundance Film Festival in the fall, Ms. Fisher spoke to The Washington Post about her mother’s health, saying, “I didn’t know how much longer she would be performing. It’s the thing that gives her life, but it was also pulling it out of her, because she’d perform and then she’d have to recover. But this is someone who wants to go back and do it now. She became very ill and now she’s bouncing back.”

For Ms. Reynolds, losing her child appears to have taken too much of a toll on her health and produced a shock from which she could not bounce back.

She could not get over the sorrow of outliving her child, one with whom she shared a deeper connection than anyone else in her life.

“No one wants to change the order of nature, that is the first thing I thought when I heard,” Dr. Victor Fornari, a psychiatrist at Northwell Health on Long Island, told The New York Times. “A parent outliving a child—it’s one of the most unspeakable things there is.”

Todd Fisher, son of Ms. Reynolds and brother of Ms. Fisher, told reporters that his mother had trouble accepting the death of her daughter and stated simply, “I want to be with Carrie.”