Bipolar disorder is a serious medical illness that causes shifts in a person's mood, energy and ability to function, according to the National Institute of Mental Health. In schizophrenia, patients can become delusional or paranoid and become self-destructive.
Doctors prescribe a variety of drugs to treat both illnesses, but medications are only effective when used continuously over the long term.
Cyndi Caron, president and founder of LostNMissing, the nonprofit organization that helped to find Rogers, said the number of missing adults with psychiatric disorders may be much higher than government statistics, and they are less likely to be found alive.
"Of the 40 to 50 children who are runaways or abductions, only two or three are located deceased," Caron said. "But for missing adults, the numbers are staggering --75 percent who are located are deceased when they are found."
Some kill themselves, others are found murdered, but for many an altered mental state causes their demise.
Eric James, 33, went off his bipolar medications and just walked in to the ocean at Rye Beach, N.H., where authorities found his body four weeks after he went missing.
Cynthia Young of Hannibal, Mo., said police have no leads on the whereabouts of her daughter, Christina Whittaker, who is bipolar and has anxiety and panic attacks.
Whittaker, who is 21, was last seen Nov. 13, 2009, leaving a local bar late at night after erratic behavior led to an argument with the bartender.
Since Whittaker's disappearance, her 10-month-old daughter cries every day, too young to understand.
"I honestly don't know if she took off on her own or if the wrong person got a hold of her," said Young, 47. "She's very childlike and had never been away from home."
Young fears that if her daughter is alive, she could be in danger because she has gone "cold turkey" off all the medications she has taken since she was 18.
But she also knows that Whittaker was frustrated with the side effects of those drugs and often took them incorrectly or not at all.
That, says Young, could have actually caused Whittaker's "mood swings" and ultimately her disappearance.
Jarrett Lee Burton disappeared April 4, 2007, near his home in Bethlehem, Penn., after going off his medications for bipolar disorder and attention deficit disorder.
"Something is not right about that night," said his sister, Janell Bennett, of Washington, D.C.
Burton, a star student who was a junior usher at the inauguration of President John F. Kennedy, had his first breakdown while a student at Kenyon College.
"He had early signs and would slip back and forth," she said. "But he started acting weird after that. He was on all different types of meds."
A laboratory microbiologist, Burton had quit his meds, which he claims "weren't working anymore," and precipitated behavioral outbursts, according to his sister.
He had a "horrific fight" with his girlfriend and broke a window in the house, she said, storming into the rain dressed only in a ripped shirt and pants.
Bennett, who looks like Burton's "fraternal twin," said she is convinced he has wandered off and is too ashamed to return to his family.
"We were six years apart, but we had this weird connection," she said. "I get a glow in my chest that says he is alive getting medical help.
"He has a golden tongue, is very intelligent and if he is on medication, I am convinced he has found a way to change his identity."