Deaths due to substance abuse, particularly of alcohol and opioids, rose sharply among older Americans in 2020, the first year of the coronavirus pandemic, as lockdowns disrupted routines and isolation and fear spread, federal health researchers reported on Wednesday.

Alcohol and opioid deaths remained far less common among older people than among those middled-aged and younger, and rates had been rising in all groups for years. But the pronounced uptick — another data point in the long list of pandemic miseries — surprised government researchers.

Deaths from opioids increased among Americans aged 65 and older by 53 percent in 2020 over the previous year, the National Center for Health Statistics found. Alcohol-related deaths, which had already been rising for a decade in this age group, rose by 18 percent.

“The rate of alcohol deaths in older people is much lower than for younger adults, but the change caught our eye,” said Ellen Kramarow, a health statistician at the center and the lead author of the report, which analyzed death certificate data.

Overdose deaths from synthetic opioids account for fewer than 1 percent of deaths in people over 65, Dr. Kramarow noted. “But the shape of the curve jumped out at us,” she said.

Physiological changes that occur with aging leave older adults more vulnerable to the ill effects of alcohol and drugs, as metabolism and excretion of substances slow down, increasing the risk of toxicity. Smaller amounts have bigger effects, researchers have found.

Alcohol and opioids can interact poorly with prescription medications that many older adults take for common conditions like hypertension, diabetes and mood disorders. Misuse can lead to falls and injuries, exacerbate underlying medical conditions and worsen declines in cognition.

Substance abuse by older adults is often missed by health care providers, who rarely refer these patients for treatment. Many facilities that offer rehab services tailor their programs to younger populations. Older patients have different needs and may be uncomfortable receiving treatment with people who are only as old as their children or grandchildren.

Many baby boomers have struggled with addiction since they were young adults. Some fell off the wagon after retirement or during the pandemic, when they suddenly had more free time and little structure and lost access to treatment because of shutdowns and fear of infection.

The death rates indicate a widespread problem with substance abuse among the elderly. Though alcohol and drug use typically subside with age, nearly a million adults aged 65 and older have a substance use disorder, according to government data. Some 3 percent use marijuana, and one in 10 binge-drink, which is defined for men as having five or more drinks on a single occasion, and for women as having four or more.

“This is a hidden population that is often ignored,” said Dr. Frederic Blow, a professor of psychiatry and director of the University of Michigan Addiction Center.

Dr. Blow said that comparatively few older Americans go into treatment. Families and spouses are embarrassed, and health care providers tend to be less aggressive about referring older patients to rehab, he added.

“Younger people go to get care because their family gives them an ultimatum or their employer has identified the problem, whereas the number one way older individuals get to treatment is through the criminal justice system,” often after an arrest for drunken driving, he said.

Lochiel P., a 72-year-old man in Albany, N.Y., who asked that his last name be withheld, started drinking when he was 18 (which was then the legal age) and began smoking marijuana and using psychedelic drugs in college.

He had been in and out of treatment his entire life. But he had been sober for eight years when his retirement triggered a relapse.

“I never smoked marijuana before I went to work or during the workday — only when I went home,” he said. But after retiring, he said, “I smoked marijuana all day long and drank a pint of vodka every day, starting with one half-pint at noon and the second in the evening.”

He was miserable, and his wife was about to leave him, he said, when he was finally ordered into treatment after being stopped for driving under the influence.

He has now been sober for four years and has become a recovery peer advocate at Senior Hope, an outpatient clinic in Albany that caters to people aged 50 and older who are struggling with substance abuse.

The program is the only one of its kind in New York to offer non-intensive treatment outside a hospital to people in that age group, according to Nicole S. MacFarland, Senior Hope’s chief executive officer.

Treatment groups are smaller, which is preferred by older patients, and facilitators make sure to speak loudly and slowly to accommodate those with hearing and cognitive deficits, she said.

The new federal data offer granular insights into who is at highest risk. Men are more likely to suffer alcohol-induced deaths: In 2020, the rates for men aged 65 to 74 were more than three times as high as those among women of the same ages.

Alcohol-related death rates for men aged 75 and older were four times as high as among similarly aged women, according to the new report.

Native American and Alaska Native people aged 65 and over experienced the biggest increase in age-adjusted alcohol-induced death rates in 2020, with the rate climbing almost 50 percent from 2019. The figure was more than twice as high as the rate among older Hispanic Americans.

White Americans had the next highest death rate, with lower figures for Black Americans and the lowest ones for Asian American seniors. Over all, 11,616 Americans aged 65 and older died of alcohol-induced causes in 2020.

About 5,000 older adults died of drug overdoses. But that number represents a tripling of the drug death rate over the past two decades, with faster increases among men in recent years.

Drug overdose death rates for men aged 65 and over are highest among Black men, compared with men from other racial and ethnic backgrounds. Among women, overdose death rates are highest for Black women aged 65 to 74, while white women have the highest death rates among women aged 75 and over.

Aging baby boomers — the Woodstock generation — had more exposure to alcohol and drugs than previous generations, who viewed the use of such substances as a moral weakness and were much less familiar with marijuana, Dr. Blow said.

The fraying of social networks and shutdowns during the first part of the pandemic exacerbated substance abuse, just as access to cannabis and alcohol increased — one could order drinks or cannabis over the phone and have them delivered to one’s home, Dr. Blow said.

“When you add that to feelings of loneliness and isolation, of feeling at the end of the world in some ways, it became an impetus for people to start using more than they ever had in the past,” he said.