Aubrey Huff of the San Francisco Giants was placed on the 15-day disabled list due to anxiety.

He's gotten some treatment and will continue to get treatment, Giants manager Bruce Bochy told the San Francisco Chronicle of Huff, who was a key component of San Francisco's 2010 World Series championship team but who has struggled of late.

Huff has had to deal with difficult situations since an early age. When he was 7 years old, his father was murdered.

His play has been on a decline and he played second base for the first time in his career Saturday against the New York Mets.

A longtime first baseman, Huff forgot to cover second base during a double-play situation and took a lot of heat over his mental blunder.

Dr. Redford Williams, director of Duke University's Behavioral Medicine Treatment Center, said anxiety and panic attacks can be caused by the types of experiences Huff has had to endure.

A very stressful life event can trigger a post-traumatic stress reaction, which could, in persons at high risk due, e.g., to adverse childhood conditions [such as Huff's father's murder], progress to post-traumatic stress disorder, he wrote to ABC News in an e-mail.

Huff is not the first Major League Baseball player to be sidelined by anxiety. Click through the slideshow to see other players who had to deal with the disorder.