Publisher Health

There are more Americans who say they have serious cognitive problems — with remembering, concentrating or making decisions — than at any time in the last 15 years, data from the Census Bureau shows.

The increase started with the pandemic: The number of working-age adults reporting “serious difficulty” thinking has climbed by an estimated one million people.

About as many adults ages 18 to 64 now report severe cognitive issues as report trouble walking or taking the stairs, for the first time since the bureau started asking the questions each month in the 2000s.

And younger adults are driving the trend.

The sharp increase captures the effects of long Covid for a small but significant portion of younger adults, researchers say, most likely in addition to other effects of the pandemic, including psychological distress. But they also say it’s not yet possible to fully dissect all the reasons behind the increase.

Richard Deitz, an economist at the Federal Reserve Bank of New York, analyzed the data and attributed much of the increase to long Covid. “These numbers don’t do this — they don’t just start suddenly increasing sharply like this,” he said.

In its monthly Current Population Survey, the census asks a sample of Americans whether they have serious problems with their memory and concentration. It defines them as disabled if they answer yes to that question or one of five others about limitations on their daily activities. The questions are unrelated to disability applications, so respondents don’t have a financial incentive to answer one way or another.

At the start of 2020, the survey estimated there were fewer than 15 million Americans ages 18 to 64 with any kind of disability. That rose to about 16.5 million by September 2023.

Nearly two-thirds of that increase was made up of people who had newly reported limitations on their thinking. There were also increases in census estimates of the number of adults with a vision disability or serious difficulty doing basic errands. For older working-age Americans, the pandemic ended a yearslong decline in reported rates of disability.

The rise in cognitive issues aligns with a common symptom that plagues many Covid long-haulers: “brain fog.”

Emmanuel Aguirre, a 30-year-old software engineer in the Bay Area, had Covid at the end of 2020. Within a month, he said, his life was transformed: “I felt like I was permanently hung over, drunk, high and in a brain freeze all at once.”

He stopped dating, playing video games and reading novels, though he managed to keep his job, working remotely. Some of his physical symptoms eventually abated, but the brain fog has lingered, disappearing at times only to steamroll him days later.

Cognitive impairment is a “hallmark of long Covid,” said Dr. Ziyad Al-Aly, chief of research and development at the V.A. St. Louis Health Care System and a clinical epidemiologist at Washington University in St. Louis.

Studies estimate some 20 percent to 30 percent of people who get Covid have some cognitive impairment several months later, including people with symptoms ranging from mild to debilitating. Research has also shown clear biological changes from the virus related to cognition, including, in some long Covid patients, lower levels of serotonin.

“It’s not just fog, it’s a brain injury, basically,” said Dr. Monica Verduzco-Gutierrez, chair of rehabilitation medicine at the University of Texas Health Science Center at San Antonio. “There are neurovascular changes. There’s inflammation. There are changes on M.R.I.s.”

Why the changes in reported cognitive impairment appear more common for younger adults is not clear. But older adults are more likely to have had some age-related cognitive decline pre-Covid, said Dr. James C. Jackson, a neuropsychologist at Vanderbilt Medical Center. Cognitive changes “stand out far more” for younger cohorts, he said.

And long Covid often presents differently in younger and older adults, said Dr. Gabriel de Erausquin, a professor of neurology at U.T. Health San Antonio. In his research, he has found that older adults with long-Covid-related cognition deficits have more issues linked to memory. But younger adults are more likely to experience difficulty with attention and concentration and, in some cases, fatigue or pain so severe their thinking is affected.

Heather Carr, 31, sold agricultural machine parts in Syracuse, N.Y., but two coronavirus infections left her largely bed-bound and barely able to string together a basic train of thought. She had trouble staying awake while driving, and eventually had to give up her job.

“I cry when I try to think, now,” she said. “My brain short-circuits.”

The number of working-age Americans with a disability who are unemployed or out of the labor force, like Ms. Carr, has roughly held steady during the pandemic.

But the number of working-age Americans with a disability who are employed has increased by an estimated 1.5 million people, census data show.

The tight labor market and flexibility of remote work during the pandemic have made it easier for people who had disabilities pre-Covid to get jobs. It’s also likely that more workers became newly disabled, by the census definition, and held onto their jobs.

That could help explain what has been so far only a relatively subtle increase in Social Security disability applications.

Long Covid is probably not the only factor driving the increase in disability, experts say.

The reported rate of cognitive disability for younger adults in the census data had been increasing slowly for years prepandemic. Experts on disability data suggest that, among many factors likely responsible for the increase, rising A.D.H.D. and autism diagnoses in children could have led more people to recognize and report their cognitive difficulties.

Then, during the pandemic, Americans spent more time alone, reported higher rates of depression and were prescribed more psychiatric medications.

“The pandemic changed the world,” Dr. Jackson said. “I do think the sum total of the mental health challenges people are having impacts cognitive function.”

Younger adults appeared to experience significantly more psychological distress than older adults, and poor mental health has been linked to cognitive issues. Polling from Gallup found that depression rates for different age groups, which were relatively similar prepandemic, shot up for adults under 45 during the pandemic, while remaining flat for older adults.

Kristen Carbone, a 34-year-old actress in New York, said her anxiety and depression spiked when the pandemic hit, and her memory began to slip. Her issues fell short of the “serious difficulty” the census asks about, but they were worse than anything she’d experienced prepandemic — and she never tested positive for Covid, so she said it was unlikely an infection was at fault. At her second job as a server, she had to start writing down every customer’s order, even the ones she used to fill by memory.

“If I don’t deal with it immediately, it doesn’t exist,” she said.

Her mental health has since recovered, she says, but her memory and focus have not.

The stressors of the pandemic could have worsened existing conditions such as A.D.H.D., said Dr. Margaret Sibley, a professor of psychiatry and behavioral sciences at the University of Washington.

“If that person’s under extreme duress or strain, those symptoms might be temporarily exacerbated,” she said.

Because the census relies entirely on self-reporting, experts say the data could also be capturing a shift in how people perceive their cognition, even absent changes to their health.

People with disabilities might have taken note of rising disability acceptance and become more likely to answer the census questions honestly, researchers say. Some young people may have been influenced by what disability researchers describe as increased awareness and acceptance of neurodiversity during the pandemic, as videos about mental illness and developmental disorders proliferated online, often encouraging people to self-diagnose. There was also an increase in advertisements for A.D.H.D. medication, Dr. Sibley said.

“Everyone was saying, ‘I’m getting this messaging online,’” she said. “The subjective experience of people receiving them was they could make anyone believe they had A.D.H.D.”

But those changes in perception are likely to have a relatively small influence on the numbers, said Monika Mitra, who directs the Lurie Institute for Disability Policy at Brandeis University. Most of the increase is probably capturing real changes in people’s health, she said.

“We need to take this very seriously as a society,” she said. “We need to understand who these people are, how they’re being impacted and what we can do about it.”