Interview: Another challenge for Cat to take in her stride

But for Cat Bull that challenge is one of the reasons she chose to study medicine. Cat has suffered from rheumatoid arthritis since she was 14 years old.

"I refuse to let this disease rule my life; I will not let it stop me doing anything."

It is this determination that has meant Cat has nearly completed three years of her five-year medicine degree at the University of Leeds.

"A lot of people, including some people on my course, don't think I will be able to do it, but I am determined to become a doctor."

She showed her commitment to her true vocation in the first week

of term.

At just 20, Cat was told that she needed to have a hip replacement, an operation normally carried out on people four times her age.

"My illness affected my A-levels, so I took a year out to resit, and also worked in a care home. I started to get bad pain in my hip. When the doctor looked at my X-ray, he said that my joint was so bad that I shouldn't have been able to walk at all. When the date came through for the operation, it was the day I was supposed to start at uni.

"I decided not to have the operation, as I knew the first term was important for meeting people and making new friends, but frankly I might as well not have been there as I slept for about 15 hours a day and hardly went out because I was in so much pain," says Cat, now 22.

The hip replacement operation was instead carried out at Christmas and was a complete success.

"Although I missed six or eight weeks of the second term, the pain had gone completely and when I went back to university people said I was a completely different person." She also started on a new trial drug, etanercept, funded by Arthritis Research UK which, she says, has helped her live a normal life.

Her improved health meant this determined young woman was going to make sure she lived life to the full, pushing herself harder

than many people with no chronic illness.

Last year she ran the London Marathon for Arthritis Research UK, and this year has been chosen by the charity to walk the first mile of the marathon with Major Phil Packer.

Arthritis Research UK has been chosen by Major Packer to be one of 26 charities to benefit from his attempts to walk the London Marathon

in 26 hours.

Major Packer, who sustained severe spinal cord injuries in 2008 while serving in Iraq, walked the London Marathon over 14 days

last year, raising over 1.3m for charity.

This year he is attempting to walk the Virgin London Marathon in 26 hours for 26 charities. Major Packer is intent on inspiring young people with a disability, and will walk each mile with a support walker aged 16-25 who will be nominated by each charity involved.

The 26 charities will raise awareness and funds in the 26 days leading up to the marathon, from April 1 to 26, and the last 365 yards of the Virgin London Marathon will see all 26 young people from the charities joining him as he crosses the finish line.

Says Cat: "Unfortunately over the past couple of months the illness has severely affected the joints in my feet and I am often unable to walk unaided at the moment. However I want to prove to myself, and other sufferers, that arthritis does not have to ruin your life or stop achieving your goals, so I will get to the finish line.

"I'm so excited to be walking with Phil; it's perfect because he wants to raise awareness of arthritis in young people. And one of the main struggles I had was people not understanding my condition. So many people said to me: 'Arthritis; at your age?'"

Many people in Cat's position would struggle to cope with the pressure she puts herself under, but she says: "I like to be busy and I make sure that I can do everything people expect me not to be able to.

"People use my illness as an excuse for me not to do things – not doing very

well in exams for example – but I don't.

"My family didn't think I'd be able to do the marathon because when I applied for it I could hardly walk, but although it was hard it was one of the best experiences of my life. When I got over the finishing line I just wanted to do it again."

Today she continues to push herself, managing to fit in training for the marathon with her studies. She plans to take another gap year next year. "I want to travel; and I plan to climb Mount Kilimanjaro for Arthritis Research UK and children's charity Childreach International."

A recent spell in hospital with stomach problems related to the anti-inflammatory drugs she was taking was a set-back, but she remains determined to reach her goal of raising 2,000 for Arthritis Research UK this year. Looking to the future, her years of being treated effectively by medical and health professionals have inspired her choice of career.

Says Cat: "I'd like to be a paediatrician. I've always wanted to work with children, and it was my own experience of illness that made me go into medicine. I had some amazing treatment from physiotherapists and hydrotherapists well as doctors and nurses, and they completely inspired me."

To sponsor Cat Bull, go to www.virginmoneygiving.com/CatBull.

RHEUMTOID ARTHERITIS

It affects more than 350,000 people in the UK. It can affect adults at any age, but most commonly starts between the ages of 40 and 50. About three times as many women as men are affected.

The genes we inherit from our parents may affect the likelihood of developing the disease, but genetic factors alone do not cause rheumatoid arthritis. Even the identical twin of somebody with rheumatoid arthritis, who shares all the same genetic material, only has a one in five chance of developing the disease. And even where members of the same family have rheumatoid arthritis, the severity of the disease can be very different.

There is some evidence that lifestyle factors may affect the risk of developing the disease. For example, rheumatoid arthritis is more common in people who smoke, who eat a lot of red meat or who drink a

lot of caffeine.

Rheumatoid arthritis is less common in people who have a high vitamin C intake.

Inflammation is a normal body defence mechanism. It is there to help fight off viruses and bacteria that cause illness.

In rheumatoid arthritis the body's immune system produces inflammation that attacks the tissues in our joints.

While "normal" inflammation dies down once the "bug" that triggered it has been destroyed, in rheumatoid arthritis the inflammation becomes a long-term (chronic) process. We don't yet know exactly what sets off the inflammation in rheumatoid arthritis.