Dementia is common for older adults living alone but many are not diagnosed, UCSF study finds
On Memorial Day, D. locked himself out of his East Bay apartment.
It was the fourth or fifth time he'd done this recently. When a neighbor saw him sitting in front of his locked door sometime later, on a chair he'd dragged over from the communal patio, she invited him inside her unit, where he spent the night until he found someone who could let him back into his own home.
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D., who is 70, is part of a growing cohort of older adults with cognitive impairment who live alone, at times in precarious situations that put them at risk of everything from neighborhood violence to disastrous medication mistakes. He is being identified only by his first initial because of safety concerns.
A team of UCSF scientists who interviewed more than 100 older adults, including D., found that roughly a third of them showed signs of mild cognitive impairment and did not have a diagnosis. D., who has a diagnosis of Alzheimer's disease, is the exception.
The scientists published a paper last month describing the participants' living conditions and the various ways they are at risk of poor health outcomes, including with difficulty being diagnosed with dementia or some other cognitive issue.
The researchers found that many older adults were on complex medication regimens that they struggled to maintain. They had a hard time with meal preparation, managing their finances and finding help with tasks they could no longer do on their own.
According to Elena Portacolone, a professor at UCSF's Institute for Health & Aging and senior author of the new research, a friend of D.'s said watching him struggle was like witnessing "a train wreck in action."
Portacolone said that description rang true. Cognitive decline is marked by poor memory, but "what is more concerning is the inability to make good decisions," Portacolone said. "That's the core of the matter."
Portacolone's interest in older adults living alone began in childhood. Her father died alone from an asthma attack when he was just 49 and traveling away from his family. She witnessed other adults in her life who were living alone and childless struggle with health issues as they got older.
Living alone, she said, "is very freeing. You can do anything you want. But at the same time, when illness kicks in, then it can be extremely debilitating."
It's not just being alone that's the problem, Portacolone noted - it's the lack of infrastructure and services to support people on their own. "In countries where these services exist, it is not dangerous. It can be lonesome, but it is not as precarious as in the U.S."
Living alone has been associated with an elevated risk of heart disease, stroke and overall premature death. It also increases the risk of cognitive decline. Researchers believe the isolation, combined with lack of support, creates stress that can cause multiple downstream health issues.
Though the risks have been identified for decades, the reality of living alone with dementia or other cognitive impairment has been largely unexplored, Portacolone said.
She began her research about a decade ago by interviewing 49 San Francisco residents age 75 or older who lived alone. About a third had signs of cognitive impairment, a figure that has remained constant in later studies. Several individuals seemed surprised to see her when she showed up for the interview, having forgotten it was happening. One woman called Portacolone to ask when they would be meeting, but Portacolone had already interviewed her.
"My main finding was that they were living a precarious existence," Portacolone said. Several study participants asked Portacolone for help.
Those initial interviews led to a larger study that included more than 100 subjects across California, Louisiana and Michigan. Results of the study were published last month in the journal JAMA Internal Medicine.
Study participants had problems with medication management, including stress over messing up complicated drug regimens and suffering debilitating side effects while alone. Many participants were distrustful of mainstream medicine, often out of concern that they would be removed from their homes and lose their independence. Participants also expressed difficulty managing healthcare systems for everything from making appointments to accessing crucial services.
In many cases, study participants had some sort of caregiver, but it was a friend or family member who did not live with them and could not always be counted on.
Much of dementia care focuses on the "dyad," or the relationship between the patient and their primary caregiver, said Dr. Matthew Growdon, a UCSF geriatrician who worked on the research with Portacolone.
"And that's wonderful," Growdon said. Caregivers can play an important role not only in caring for the individual at home, but being a liaison between the patient and the medical team.
"But how do we manage when we don't have a built-in informant and there's fragmented knowledge and a lot of uncertainty about what's happening at home?" Growdon said. "There are not a lot of insights on the provider side into the patients' lived experience. And on the patient side, they mistrust or feel lost and confused in the system.
"You end up with this black box effect," he said.
Portacolone met D. through her research, and she has stayed in touch as he tries to navigate healthcare systems that are not designed for people with cognitive impairment.
D. was diagnosed with Alzheimer's disease sometime in the past decade, though he's not sure exactly when. He also has diabetes. For a long time, he managed OK, but in recent years the cognitive decline has worsened. He's noticed his memory slipping more, and he loses his train of thought easily.
"I'm grieving," D. said of the cognitive decline. "It's a loss."
D. lives with his rescue cat in a subsidized one-bedroom apartment in a neighborhood with high crime rates. But he's near a busy shopping area and walking distance from a senior center where he goes for lunch every day. He said he loves living alone, but likes to "mix and mingle," too. "Wednesdays I play Scrabble with the ladies" at the senior center.
"I have no problem walking around," said D., who sold his car soon after he was told he had Alzheimer's. "I already have a Clipper card. I'm very savvy."
His apartment is tidy but cluttered, a rabbit warren of stacked boxes and keepsakes, with a nook for his computer and another for a reading chair. He carries two sets of keys now - one on a chain around his neck, another on his hip - but he's thinking of hiding a third outside his door. Lists are taped to the apartment walls, reminders to do one task at a time, to take out the trash, to clean out the dishwasher.
On his kitchen counter sits a giant pillbox container that holds a month's worth of medication; a friend fills it for him at the start of each month so he doesn't have to manage them every day. Because of D.'s diabetes, his daily regimen is complicated and requires taking certain drugs at certain times of day.
In many ways, D. has been lucky to have a friend who has stepped in as a caregiver. She had a spare key and would let him in when he locked himself out. When D. made a trip to Texas to see family four years ago, the friend made all the plans, typing up a detailed list of instructions for his travel days.
But that friend has her own health issues, and they haven't been getting along well lately, at least in part due to D.'s cognitive issues. D. qualifies for a home health aide, but it's up to him to find the aide and complete all the paperwork.
Just last week, Portacolone spent an afternoon with D. helping with the forms. He'd started the process on his own, but was told after multiple phone calls that he was missing a case number and would need to start over; D. clearly was not able to follow the complex instructions.
"A person living alone with Alzheimer's disease should not be left alone to understand this form," Portacolone said. "It's surreal."
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This story was originally published June 8, 2026 at 10:35 AM.