A year ago, Marc and Kathy Cochran were looking forward to a summer trip to Greece. Kathy, 68, had been diagnosed with early-onset Alzheimer’s disease in 2012, but she was functioning well and enjoying herself, which her husband of 48 years attributed to regular exercise and an active and varied social life.

That crashed to a halt when the novel coronavirus hit. The couple stopped going to restaurants, visiting friends or seeing their adult children. They even had to stop walking their dogs because the gregarious Kathy liked to run up and hug her neighbors and did not understand why that had become unsafe.

The changes put her into a tailspin. “It was just like the bottom dropped out,” Marc said. “I couldn’t get her to be calm.” In the ensuing months, her cognitive function declined so precipitously that she was moved to a memory-care facility, and she died in September.

Her husband blames the pandemic. “I can’t tell you that she wouldn’t have, but I could see a definite demarcation point from the time we shut down to the time she had to go into memory care,” he said. “One of the things that made her happy was seeing people, smiling at them, laughing with them, hugging them, and when she couldn’t do that . . . she would become agitated.”

If the pandemic did accelerate Kathy’s decline and death, she is probably not alone. Preliminary reports from the Centers for Disease Control and Prevention indicate that there were at least 42,000 more deaths from ­Alzheimer’s and other dementias in 2020 compared with the average of the five years prior, according to a report released Tuesday by the Alzheimer’s Association. This was approximately 16 percent more than expected.

About 40 percent of covid-19 deaths in the United States have been residents or staffers of long-term-care facilities, said the report, which is the organization’s annual Facts and Figures assessment.

The report also noted that by 2050, the number of people 65 and older living with Alzheimer’s in the United States will skyrocket from 6.2 million now to 12.7 million, as the number of people in that age bracket increases from 58 million to 88 million.

The biggest spike in deaths among dementia patients in 2020 occurred early in the pandemic, when the virus raged in nursing homes and other communal-living locations, killing many residents before medical professionals and caregivers had a full understanding of how to protect people, said Maria Carrillo, the association’s chief science officer. “I think we’re going to see a leveling out of that now that we’re getting vaccines,” she said.

But for people with cognitive impairment who did not die of covid-19, the effects of the coronavirus may be deadly far beyond the initial surge. For the past year, the pandemic has interrupted routines, divided families and curtailed social interactions that might have helped keep patients functioning longer.

Social isolation has been shown to correlate with cognitive problems among older people. But determining the depth of its effect, along with the impact of disrupted routines, pared-down medical care and other factors during the pandemic will take time, Carrillo said.

“There is so much to unpack,” she said. “We’re going to be analyzing this data in the coming years.”

Along with studying people previously diagnosed with dementia, researchers will need to follow the rates of new diagnoses, which may be delayed until older people and their families feel more comfortable with in-person medical appointments.

“People might be holding off on going to the doctor . . . or their physicians are only doing virtual visits,” where it can be harder to detect subtle changes in cognitive function, Carrillo said. Putting off appointments could have delayed the diagnosis of co-morbidities such as diabetes, she said. “Have the safety measures actually impacted our older population [by] accelerating dementia? We don’t know yet,” she said.

A study published in October found that the pandemic has had negative effects on dementia and pre-dementia patients, in direct and indirect ways.

A survey of 389 patients and 147 caregivers associated with a memory clinic in the Netherlands found that patients had experienced an increase in social isolation, psychological symptoms and discontinuation of care. Both patients and caregivers said they were worried about faster cognitive decline, and three-quarters of caregivers reported an increase in problems including apathy, sleeping issues, agitation and repetitive behavior.

These could have a snowball effect, the report said, noting that “a recent review showed that patients who exhibit aggression, wandering or disinhibition are even at higher risk of catching and spreading COVID-19, triggering a vicious circle as research now shows that catching COVID-19 has adverse impacts upon the brain and cognition.”

The study, which was published in the journal Frontiers in Psychiatry, surveyed patients living alone or with partners or family members and included both those whose cognitive decline was diagnosed by tests and those who performed normally in tests but had subjectively experienced cognitive decline.

Because of the pandemic, many people sought out social connections online, “but this is more difficult for patients with cognitive complaints,” the study said. “We even found that some patients did not go outside at all.” That included skipping visits to the doctor or hospital, either by choice or because health facilities were closed.

“The loss [of] structure and social cohesion may be the final push toward onset of overt symptoms,” the study said, adding that symptoms could also have been exacerbated by uncertainty and anxiety tied directly to the pandemic.

Anecdotally, people living with dementia and their caregivers are reporting similar experiences, said Sam Fazio, senior director of quality care and psychosocial research at the Alzheimer’s Association.

During a recent roundtable discussion between dementia care provider industry leaders, “all of them see their residents becoming more impaired with the lack of socializing, the lack of being able to come out of their room,” he said.

Fazio warned that relatives of those who have been isolated inside care facilities should expect to see a stark difference once they are able to visit.

“Their family members may not be functioning as well as they were before,” he said. “Just seeing them through the window or talking on the phone, they’re not going to be prepared for the decline.”

Both the Alzheimer’s Association report and the Netherlands study noted an increased burden during the pandemic on family and friends who are caring for people with dementia.

“Caregivers have been limited in or completely barred from visiting and communicating with relatives who live in long-term care residences due to COVID-19 lockdown procedures,” the association’s report said, noting that adult day programs in many states have also been interrupted or closed. “These and other factors shaped by the COVID-19 pandemic have caused emotional distress and other negative outcomes among caregivers.”

Family caregivers who could engage in phone and email contact with relatives in long-term-care residences indicated greater emotional well-being for themselves and their relatives compared with those relying on residential care staffers for communication, the report said.

The Netherlands study found that more than half of caregivers reported a higher burden during the pandemic and noted that a report by the Dutch patient organization Alzheimer Nederland about a similar survey showed a higher caregiver burden in 80 percent of respondents.

Professional care workers have also been adversely affected, the Alzheimer’s Association report said. “The lack of personal protective equipment (PPE), lack of transparent communication about the extent of COVID-19 outbreaks within and across facilities, work-related strain due to COVID-19 management protocols, and increases and abrupt changes in workload have all contributed to a nearly untenable work situation for various types of staff in residential long-term care,” it said.

“Whether these staff are receiving meaningful support to successfully manage their feelings of emotional strain, bereavement (due to the high proportion of resident deaths concentrated in residential long-term care due to COVID-19) or other adverse consequences is unknown,” the report said, adding that experts warn that without significant changes, “residential long-term care settings such as nursing homes will again be susceptible to future pandemics or similar crises.”

Other research into dementia and covid-19 includes an international study initially funded by the Alzheimer’s Association that will follow approximately 40,000 survivors of the disease in as many as 40 countries to understand the long-term effects on their brains and nervous systems as they age.

Decades of evidence from other respiratory viruses, along with observations of patients in recent months, suggest that such infections may increase a person’s risk for Alzheimer’s, Parkinson’s disease and other brain disorders.

By the end of 2020, between 1 and 2 percent of the world population had developed covid-19 with symptoms, and perhaps as many as 5 percent more had had asymptomatic infections, according to a lead researcher in that study. It is unknown how many more will be infected, but if even a fraction of survivors have increased cognitive difficulties, the effects could have devastating social and economic repercussions.