"You can't separate the mind and body as much as we used to think," says neurologist Dr Alex Lehn. "The mind can make you sick."
He's speaking with s Jenny Brockie, as this week's delves into the world of health anxiety and the power of the human brain to convince us we're sick - and even produce symptoms.
In two scenarios, the mind appears to have a strong hold over how our bodies function: health anxiety, and neurological disorders that create physical changes.
Jean Flynn is of the first category, also known as (IAD): an form of hypochondria associated with general health anxiety, which sees a person become persistently focused on their physical health, accompanied by an unrealistic fear of developing severe disease. Those who suffer from it often have mild, or no symptoms, but believe changes in the body are the sign of something more sinister.
For Jean, an itchy feeling had her convinced she had liver disease; pins and needles and numbness made her certain she had multiple sclerosis; other symptoms were omens of a brain tumour, or a prolapsed uterus.
She is however, in otherwise perfect physical health. Yet the constancy of her anxiety - thinking about it "Oh, every three and a half minutes, all day, all the time" - can exacerbate her symptoms.
She often doesn't quite believe the results of her tests when they come back - another characteristic of the disorder.
Further Reading
Is hypochondria still a relevant diagnosis?
Stephanie Huynh knows Jean's feelings all too well.
She also suffers from IAD, and has found herself sure a bruised nail is the sign of melanoma of the nail; a mole she hadn't noticed before a warning sign of skin cancer; an upset stomach an incontestable symptom of bowel cancer.
Like Jean, she finds the anxiety to be crippling. In one instance, she remembers driving to the doctor without any doubt she had a serious illness.
"As I got in I was almost in tears," she says. "I sat there and I was shaking and I couldn't breathe and then I said okay, I'm letting you know that I do feel very, very anxious, this is what I think I have."
I was shaking and I couldn't breathe and then I said okay, I'm letting you know that I do feel very, very anxious, this is what I think I have.
Dr Louise Stone, who also joins the program, says it's important for GPs to recognise IAD as a serious and debilitating disorder.
"It is anxiety and it is really distressing and it invades your life and takes over things. I often say to people you know, it's like a phobia [of illness]."
She says treatment can be difficult in the age of , where the desire for reassurance can be easily satisfied.
"I think when you have health anxiety you're seeking reassurance all the time and part of learning to live with it is learning to tolerate the fact that you can't always be reassured, and you have to live with that uncertainty," she says. "And that's the really hard part, I think, of living in our culture. Particularly with Dr Google around every corner where you can look anything up and find anything."
Jean now asks her husband to search symptoms for her. Occasionally, he edits out the worst details.
"The hard thing for us as doctor is if we over investigate we run the risk of harm," says Stone. "You know, every test that we do runs the risk of making another diagnosis the patient doesn't have ... So if we over investigate there's a problem and if we miss something there's a problem. So it's quite difficult to walk that quite narrow line."
"The best friend for GPs is time and what we often do is use time ... to see how this evolves and wait and watch and see what happens." 
For Miranda Licence, the evolution of her symptoms was not so gradual.
Stephanie Huynh, on Insight Source: Insight
One Sunday afternoon, after heading out for a jog, she returned home and, exhausted, laid down for a nap. When she awoke, she could no longer use her legs.
"It wasn't like I was paralysed, but I didn't know how to move,” she says. "I guess the best way to describe it is like you've had far too much to drink and you're kind of staggering all over the place and you are really off balance."
Even more perplexing was the fact that while she could not walk forwards, she could walk backwards. She could also run.
Miranda falls into the second category of people whose minds exhibit a strong power over their bodies. With no medical reason as to why she couldn't remember how to walk, she was diagnosed with (FND), or Conversion Disorder: a condition where bodily symptoms are thought to be caused by problems in the nervous system but no physical neurological cause can be found.
Neurologist Dr Alex Lehn describes FND as "a group of disorders and the hallmark feature [is that] these are genuine, real disorders with genuine real symptoms ... but no organic cause can be found for them."
"So people have MRI scans and blood tests and lumbar punctures and all those tests come back normal because in these patients their brain hardware is normal," he says. "Just their brain software is not working properly."
In these patients their brain hardware is normal, just their brain software is not working properly.
For others, the power of the mind is more mysterious. Paul Bonner, who also has a form of FND, experienced seizures from 2012 with no medical explanation. When he was diagnosed with epilepsy, a seemingly attributable cause was a relief.
But with medication, the seizures did not stop and it was only before a radical brain surgery that doctors realised the cause was psychological; a traumatic event in Paul's childhood, when he was sexually assaulted.
Paul says it was as if his brain was a computer, where the working memory was full and an overload, or inability ot process that particular memory, had caused it to reboot.
Psychiatrist Dr Andrew Court agrees that one theory around FND " ... is to be so overwhelmed by the anxiety and stress that you kind of disconnect and disassociate from it and kind of cause a neurological symptom."
Court "definitely" believes that we can think ourselves sick; particularly when existing vulnerabilities - trauma, experiences of depression and anxiety - make us susceptible to neurological changes.
Lehn agrees, and adds that while the power of the human brain might be causing these symptoms, it does not make them any less real.
"What I can tell [patients], is that these are real genuine disorders," he says. "This is not just in your head ... this is not something you're making up and these things are treatable.
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