‘This Is Us’: This New Heartbreaking Theory Regarding Rebecca’s Memory Loss Will Have You Rewatching Every Episode Since the Show Began

This is Us is about to return from a very long midseason break, and fans are ready for it. The midseason finale left viewers with a terrible feeling regarding Rebecca’s (Mandy Moore) deteriorating condition.

We are prepared to find out precisely what is going on with the matriarch of TV’s favorite family. Let’s take a look at the new heartbreaking theory that fans have after rewatching the last three and a half seasons.

Mandy Moore
Mandy Moore | Amy Sussman/Getty Images

Mandy Moore indicates that Rebecca does not have Alzheimer’s Disease on ‘This Is Us’

Right now, most fans believe that the beloved mother on This Is Us ends up with Alzheimer’s Disease or dementia. However, Moore debunked that theory on March 25, 2019.

“My reaction was, ‘Oh, Rebecca,'” Moore told Glamour how she felt about her character’s ailment. “Dan Fogelman is a genius. I was like, ‘Yeah. OK. I see that. I believe that. I understand that. Yep.'”

“I love how people are sleuths,” she continued regarding the fan theory that Rebecca has Alzheimer’s. “I love that! That’s a good theory. Not true, but I like it.”

Rebecca often forgets things on the show and recently lost her phone several times, so it is easy to assume that she has dementia. However, now that we are almost four seasons into this series, we know that things are never what they seem.

What did fans notice about Rebecca when they rewatched the show from the beginning?

After going back to season 1 of This Is Us, fans have come up with a new theory regarding the matriarch’s ailment.

“I’m on the ‘Pilgrim Rick’ episode, and Rebecca asks Kevin ‘Hey, what’s the name of your play again?'” writes one fan on Reddit. “To which Kevin replies, ‘You serious? I told you like eight times.’ Do you think this could’ve been a foreshadow of what’s to come?”

Viewers believe that there are numerous indications of forgetfulness from Rebecca going back to when the big three were young children.

“Also, there was the scene of Rebecca and Jack in the kitchen and him talking about how he had a meeting in Doylestown,” added another Redditor. “She was surprised to hear that he had gotten the Doylestown account, and he said he had mentioned it to her a few times already. Her response was, ‘I would have thought I would have remembered that.'”

What might all of this forgetfulness indicate is wrong with Rebecca?

“Also, remember when she went to the hospital for her dizzy spells,” added another viewer. “The one where Jack took her to his favorite tree. There are lots of little clues to something being wrong with her brain.”

Some symptoms of a brain tumor in the frontal lobe include; personality changes, increased aggression or irritation, and vision/speech problems, according to the National Brain Tumor Society.

Throughout the first half of season 4, Rebecca became irritable much more quickly. She also displayed a few hallucinations, so her symptoms do fit those of a frontal lobe brain tumor.

“As your tumor grows, it can press on surrounding tissue, affecting the function controlled by that part of the brain,” according to the publication. Forgetting words and short-term memory loss are associated with a brain tumor in the temporal lobe.


These two parts of the brain are right next to each other, so Rebecca may have a brain tumor in the middle of the two lobes that is growing. It might be tiny when her children are young and then grow as she gets older.

Luckily, the promo for the next episode does reveal that Rebecca is receiving test results from a doctor, so we might find out soon if this fan theory is correct. The midseason premiere of This Is Us is finally here on Tuesday at 9 p.m. Eastern on NBC.