Since her conviction in the murder of British roommate Meredith Kercher in 2007, Knox has said that she longs to go home and daydreams of catching up on Harry Potter movies and lying in the grass of her Seattle back yard.
After spending four years in a cramped cell in an Italian prison, Knox appeared elated but emotional as an appeals court in Perugia overturned her 26-year sentence.
But her pale face and thinning hair reveal the toll prison life has taken on the young woman psychologically. Even before her fate was sealed, cameras showed her nervous breathing and a face buried in hands, ready for the heaving tears that would follow.
"She still has had a horrific experience and her sense of trust in police and in people is gone," said Ann Rosen Spector, a clinical psychologist from Philadelphia. "Some people may still believe she did it and will treat her differently. Her name is well known.
"It will take time to get back to normal," said Spector, who specializes in depression, stress and anxiety issues. "She lost four years of her life."
Knox was found guilty of slandering Perugia police for claiming during her trial that the police abused her and cuffed her on the back of her head.
In the past months, the carefree college student has seemed increasingly more fragile and less naive. Her parents, Edda Mellas and Curt Knox, have told ABC that she has broken out in hives and is having trouble sleeping and eating.
Her father told CNN recently that, "We'll take her home and find out what kind of trauma she's experienced in prison -- even if she wants to talk."
Knox arrived in Italy in 2007, a 20-year-old college student eager to learn another culture, thousands of miles from her Seattle home. But only months into the first semester, her apartment roommate, Kercher, was brutally murdered.
Knox and her then-Italian boyfriend Raffaele Sollecito were arrested for the murder, and a jury in Perugia, Italy, eventually found them guilty. Sollecito's conviction was also overturned.
The American press has been sympathetic to the kooky, free-spirited Knox, who is now fluent in Italian. But local accounts have been searing, calling her an "angel face with icy eyes"
"This is really traumatic for her," said Judy Kuriansky, an adjunct professor of clinical psychology at Columbia University's Teachers College. "She is going to be just as wrecked as Casey Anthony -- the trial and the lurid details -- the accused sex play and throat slashing and a drug-filled orgy. This will continue to follow her forever."
"There is no way she will have a normal life," said Kuriansky. "No matter where she goes, they will think of her as Foxy Knoxy."
Knox has also faced harsh judgment from her murdered roommate's family. John Kercher contended the trial was fair and was critical of the way the press has given Knox "celebrity" status.
"I lost a friend in the most brutal inexplicable way," Knox said in her statement to the jury. "My trust, my full trust in the police has been betrayed. I had to face absolutely unjust charges, accusations and I'm paying with my life for something that I did not commit."
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Even if Knox decides to eventually finish college, she will have challenges, according to Spector. "She was on a very clear path and she has gotten off that path."
"She will have some catching up to do, not to mention post-traumatic stress," said Spector. "She will have dreams, waking up back in prison again. She will have low trust issues. It will be a long time before she is secure in her own skin."
Prison itself changes a person, according to George Everly Jr., associate professor of psychology at Johns Hopkins Bloomberg School of Public Health.
"Personalities change after enduring stress," he said. "You take someone's freedom away, restrict their activities and what they do. Captivity, in short, is very stressful and there is the possibility that it will have a long-term adverse effect -- not just psychological, but physical health, as well."
Everly said if 100 people are exposed to trauma, only about half of them will develop post-traumatic stress. "Part of the answer is how a person perceives it," said Everly. "If she is truly innocent or believes herself to be innocent, then it is devastating."
Knox's parents said they had hoped her life could return to some normalcy, after celebrating all the missed birthdays and holidays. They have alternated paying her visits in prison, but for the appeals trial, the whole family descended on the small town in Umbria.
"Four years ago I was four years younger, but fundamentally I was younger because I had never suffered before four years ago," Knox told the jury. "Because of four years ago, I didn't know what tragedy was. It was something I would watch on television. That didn't belong to me."
"I want to go home," she said. "I want to go back to my life. I don't want to be punished. I don't want my future to be taken away from me for something I didn't do. Because I am innocent. Just like he is innocent. We deserve freedom. We didn't do anything not to deserve freedom."
Like Knox, Italian student Raffaele Sollecito, now 27, was convicted in 2008 on sexual assault and murder and given a 25-year sentence.
He testified before an appeals court that the when he met Knox, she was "beautiful, happy, vivacious and sweet." He said their short time together was "a beautiful time in my life. Idyllic."
"We were free from everything," he said in court, as Knox's mother and sister burst into tears. "Our only wish was to spend the night cuddling in tenderness. This was our wish."
Knox's family has confirmed that their daughter has broken out in hives and is have difficulty sleeping and eating in prison.
"You don't ever get over it," he said of the prison experience.
"I don't know her personally -- her strengths and weaknesses, being in a strange land in a strange country, even though she is conversational in Italian, but she could experience extreme isolation and it could have an impact on her morale and she could be really traumatized by it," said Kazdin. "Trauma doesn't always come from an acute activity like war or rape."
"The stress of isolation can have an enduring impact on people's immune systems, particularly warding off bacteria and fighting off inflammation and is implicated in a wide range of diseases," he said. "She is at risk."
Normally, when people are under stress, it subsides and life goes back to normal. "But when it carries on, the changes are real," said Kazdin. "Young children who are stressed all the time have more disease and die younger. This is not tiny stuff. Will she suffer that?"
"Youth gives her body resilience, but she has less experience in coping skills," he said. "The mental and physical go together. You can get depression, trauma, stress and illness in the normal process of enduring stress and isolation."