A few years into Rogen's relationship with Miller, her mother was diagnosed with early-onset Alzheimer's disease, according to Glamour. Gradually, the couple witnessed Miller's mother, Adele, lose her memory and need assistance with tasks like eating, moving around, and cleaning herself. Together, Rogen and Miller moved her parents out to Los Angeles and bought a duplex where her father, mother, and mother's caretaker could live, but the two wanted to do more.
In 2012, they founded Hilarity for Charity, a yearly variety show that hosts various programs and events to raise awareness and funds for Alzheimer's research. The nonprofit celebrated 10 years of operating in January 2022, and Miller took to Instagram to commemorate the special event.
"Happy Birthday to @wearehfc. Somehow it's been 10 years from that first incredible event. We had no idea what we were doing, I had to run backstage and remind Seth to even mention Alzheimer's right before the end of the show, but we managed to pull it off and haven't stopped since. We've raised $15 million, awarded over 350,000 hours of free respite for caregivers, and reached over 3M people through our programs and events," she wrote in part.