The number of American adults seeking mental health treatment has increased since the start of the COVID-19 pandemic, and younger adults appear to be struggling the most, according to new federal data.

Nearly one in four Americans — 23% — ages 18 to 44 reported in a survey they had received mental health treatment in the previous 12 months, according to a study published Wednesday by the National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention.

That number climbed from 18.5% in 2019. In fact, in 2019, before the pandemic, 18- to 44-year-olds were the least likely adult group to seek mental health treatment but last year were the most likely, according to the survey.

Mental health treatment is on the rise among adults overall — up from 19.2% in 2019 to 21.6% in 2021. However, the differences were statistically insignificant for other age groups — slightly higher for 45-64 and slightly lower for 65 and older.

The report defines mental health treatment as having taken medication for mental health, receiving counseling or therapy, or both. 

Women 18-44 were more likely to receive treatment, rising from 23.8% in 2019 to 28.6% in 2021. Men in that age group also saw an increase — 17.8% in 2021, up from 13.1% two years earlier.

Thirty percent of non-Hispanic White adults 18-44 say they sought care, up from 23.8% in 2019. The number for non-Hispanic Asian adults in that age group receiving treatment, meanwhile, nearly doubled, going from 6% to 10.8%. 

The CDC report did not suggest reasons for the increases. But there has been much research linking worsening mental health to the COVID-19 pandemic, which has killed more than a million Americans, left countless others who were infected in fear about their short- and long-term health, closed businesses and schools for a time, led to millions of job losses and forced people into isolation.

In March, the World Health Organization reported that in the first year of the pandemic, global prevalence of anxiety and depression increased by 25%. 

“This is a wake-up call to all countries to pay more attention to mental health and do a better job of supporting their populations’ mental health,” said WHO Director-General Dr. Tedros Adhanom Ghebreyesus.

A separate CDC survey released in March also found that more than a third of high school students in the United States said they experienced poor mental health during the pandemic.

And more findings are constantly coming to light. For instance, in the past couple of weeks, the journal Lancet Psychiatry published a large study that, in the six months after being infected by COVID-19, people are at an increased risk of mental health and neurological conditions, including seizures, dementia, psychotic disorders and brain fog.

Another study published in the journal Psychological Trauma: Theory, Research, Practice, and Policy, researchers found that about two-thirds of surveyed participants experienced a distorted perception of time — that it was either speeding up or slowing down — even six months after the pandemic began. The researchers say people who lost their sense of time could be at an increased risk for mental health challenges.

As for why young adults are seeing sharper increases in mental health treatment, Calliope Holingue, a psychiatric epidemiologist, told CNN that the they entered the pandemic “at a very vulnerable life stage.”

“It's the stage at which disorders such as anxiety disorders and depression are at one of their highest levels across the life course," she said. "So there is this sort of natural vulnerability there, at the same time that the pandemic is happening."