Experts say the case of a U.S. mother accused of poisoning her five-year-old son to death with salt appears be an example of how social media feeds into the psychiatric disorder known as Munchausen by proxy, a condition in which caretakers purposely harm children and then bask in the attention and sympathy.

Lacey Spears has pleaded not guilty in a New York court to charges of depraved murder and manslaughter in the January death of her son, Garnett-Paul Spears, whose sodium levels rose to an extremely dangerous peak with no medical explanation.

As Spears moved around the country — Alabama, Florida and eventually New York — she kept friends updated on her son's frequent hospitalizations with photos and musings on Facebook, Twitter, MySpace and a blog.

"My sweet angel is in the hospital for the 23rd time," she tweeted in 2009. A series of reports on the case by The Journal News, which covers the New York City suburbs, found she kept it up right through her son's death, with 28 posts in the last 11 days of Garnett's life, including, "Garnett the great journeyed onward today at 10:20 a.m."

Marc Feldman, a psychiatrist and forensic consultant in Alabama, who wrote the book Playing Sick, said he believes the internet has contributed to the number of Munchausen by proxy cases. The illness — also known under various alternative names, including  caregiver-fabricated illness in children — is still rare, occurring in about 0.5 to two out of every 100,000 children under age 16, according to studies.

In a case exposed in 2011 in Great Britain, a childless 21-year-old woman joined an internet forum for parents, claiming to have five children and chronicling her nonexistent baby's battle with celiac disease and bacterial meningitis. Doctors at Seattle Children's Hospital found three cases of mothers who falsely blogged that their children were near death and were rewarded with support.

"There are instantly accessible and endlessly supportive groups out there that will pray with you and cry with you if you purport your child to be ill," Feldman said.

Mark Sirkin, director of the mental health counseling program at Mercy College in Dobbs Ferry, N.Y., said that with social media, "you can expand your circle from the people you know to strangers who you've never met; you're just getting that much more attention."

Kids rarely killed

While prosecutors and defence attorneys in the Spears case have yet to mention Munchausen in court papers or hearings, experts say the disorder could play a role because Spears fits the pattern of caregivers who invent, exaggerate or cause a health problem in someone in their care and then seek to portray themselves as a hero.

Spears, who was living in suburban New York when her son died, is accused of administering sodium through a feeding tube he had in his stomach while he was hospitalized. Prosecutors say she did it in the bathroom, where there were no surveillance cameras.

According to court documents, Spears told police she used only "a pinch of salt" for flavor when feeding her son fruits and vegetables through his tube.

Spears said the feeding tube was necessary because Garnett couldn't keep food down. Some friends told The Journal News they saw no sign of that. They were also confused by her claims that Garnett's father was killed in a car accident. A man who says he's the father lives in Alabama.

Her attorney Stephen Riebling said last week that the defence would focus "on the relevant facts, not fiction."

Spears' lawyers won't comment on whether a psychiatric defence is planned.

Munchausen by proxy has been suspected in several court cases over the years. In 1979, a California woman was convicted of murder for slowly poisoning one child; the case was cracked when a second baby came down with similar symptoms. In 2010, a Tennessee woman pleaded guilty but mentally ill to charges she injected saltwater into her infant son's feeding tube. In a 2010 court case in Surrey, B.C., a church pastor testified to his suspicions that a couple he knew were abusing their three children; he told the court he believed the mother was suffering from Munchausen's by proxy.

Most cases rarely end in death because the child "is the goose that lays the golden egg for somebody who's so needy of attention," Sirkin said. "It would defeat the purpose to kill the child." Often when a death occurs, it's because of a miscalculation, Feldman said.

As for treatment, Sirkin said long-term psychotherapy is required.

"It's not like a snake phobia where you can take somebody through some behavioral training and they'll be over it," he said. "This is a personality type that takes years in the making, and I think it probably involves psychotherapeutic treatment that would also take years."