Sen. John Fetterman, D-Pa., is receiving treatment for clinical depression at Walter Reed hospital, his office announced Thursday. His chief of staff said Fetterman checked himself in Wednesday night.

"While John has experienced depression off and on throughout his life, it only became severe in recent weeks," chief of staff Adam Jentleson said in a statement.

Fetterman was evaluated Monday by a doctor, who on Wednesday recommended inpatient care, according to the statement. He is receiving treatment "on a voluntary basis."

The Pennsylvania Democrat defeated Dr. Mehmet Oz in a closely watched Senate race in November, securing a key Democratic pickup in the chamber.

Fetterman has had recent health complications

Fetterman had a stroke in May of last year, which sidelined him from the midterm campaign for two months, and soon after he had a pacemaker and defibrillator implanted to treat an irregular heart rhythm.

He continues to face issues related to auditory processing. Fetterman is accompanied by aides around the Capitol who use a mobile device that translates voice to text using closed captioning.

Fetterman was hospitalized again last week after feeling light-headed at a Democratic Senate retreat. But after testing and observation, doctors ruled out the possibility of another stroke.

His wife, Gisele Barreto Fetterman, posted on Twitter Thursday asking for privacy during this "difficult time for our family."

"After what he's been through in the past year, there's probably no one who wanted to talk about his own health less than John," she said. "I'm so proud of him for asking for help and getting the care he needs."

Fellow lawmakers offer words of support

It is generally rare for sitting officials to acknowledge receiving treatment for mental health conditions. One relatively recent example, though, is Sen. Tina Smith, D-Minn., who shared her experience with depression in her 30s in a 2019 floor speech in support of legislation to expand mental health care access.

Jason Kander, an Army veteran who served in Afghanistan, dropped out of the 2018 Kansas City mayor's race due to his struggles with PTSD and depression.

Many of Fetterman's colleagues from both parties posted their reactions on social media, applauding his openness.

"Back in 2010, I was hospitalized for depression. I would not be alive, let alone in Congress, were it not for mental health care," Rep. Ritchie Torres, D-N.Y., said on Twitter. "Millions of Americans are rooting for you, Senator."

Sen. Ted Cruz, R-Texas, also posted on Twitter, saying, "Heidi & I are lifting John up in prayer." The senator's wife Heidi Cruz has spoken about her past battles with depression, and their teenage daughter has acknowledged experiencing mental health issues.

"Mental illness is real & serious, and I hope that [Fetterman] gets the care he needs," Cruz continued. "Regardless of which side of the political aisle you're on, please respect his family's request for privacy."

Depression is a common condition

Depression is one of the most common mental health disorders in the United States. According to the National Institute of Mental Health, more than 8% of U.S. adults had at least one major depressive episode in 2020.

Symptoms include persistent feelings of sadness, emptiness, hopelessness, an inability to focus, and recurring thoughts of death or suicide. But it's a treatable condition, says Dr. Rebecca Brendel, president of the American Psychiatric Association.

"There are multiple different kinds of treatments that range from medications that include psychotherapy and can also include other changes to behavior and focus on wellness and nutrition," she said.

People with symptoms should seek help, she said, and a good place to do that is with a trusted health care provider like a primary care physician.

If you or someone you know is in an emotional crisis, dial the National Suicide & Crisis Lifeline by dialing or texting 9-8-8.

NPR political correspondent Susan Davis and congressional correspondent Deirdre Walsh contributed to this report.