Allergies may put you more at risk of Parkinson's disease

Aug 9 2006

According to researchers people who suffer from allergic rhinitis may be more at risk for Parkinson's disease later in life.

Scientists at the Mayo Clinic say that risk may be as great as three times that of someone who does not have the condition.

Allergic rhinitis is an inflammation of the nasal passages which is caused by the immune system over-reacting to substances in the air and causes runny noses and streaming eyes.

The most common form is hayfever which is triggered by pollen but the reaction can also be caused by dust and animal hair; sufferers have permanent cold-like symptoms.

James Bower, M.D., Mayo Clinic neurologist who led the study says however there is little allergy sufferers can do to alter their risk of developing it.

As previous studies have suggested that people who take nonsteroidal anti-inflammatory drugs, such as ibuprofen, are less likely to develop Parkinson's disease, the research team were prompted to examine the links between diseases characterized by inflammation and Parkinson's.

In order to determine if those who developed Parkinson's disease had more inflammatory diseases, over a 20-year period they studied 196 people who developed Parkinson's disease, matched with people of similar age and gender who did not develop the disease.

The researchers say they found that those with allergic rhinitis were 2.9 times more likely to develop Parkinson's.

They did not find a similar association between inflammatory diseases such as lupus, rheumatoid arthritis, pernicious anemia or vitiligo and Parkinson's disease.

They also did not find the same association with Parkinson's disease in patients with asthma that they discovered in those with allergic rhinitis.

Dr. Bower says although the study did not examine patients' types of allergies or when they developed allergies they believe it is possible that a tendency toward inflammation is the key link between the diseases.

Dr. Bower says people with allergic rhinitis mount an immune response with their allergies, so they may be more likely to mount an immune response in the brain as well, which could produce inflammation, which may release certain chemicals in the brain and inadvertently kill brain cells.

Dr. Bower says the study does not prove that allergies cause Parkinson's disease, but it does point to an association between the two diseases.

Dr. Bower and colleagues hope that the clues in the study may give scientists a strong hint about inflammation's role in Parkinson's and lead to the development of medications to block the inflammation.

The researchers advise sufferers to continue with their normal medicines to try to prevent their allergic symptoms.

About a third of Britons will develop an allergy at some point in their lives and around 12 million get hayfever.

Parkinson's is a complex disease which affects nerve cells (neurons) in the part of the brain that controls muscle movement.

People with Parkinson's disease often experience trembling, muscle rigidity, difficulty walking, and problems with balance and coordination.

These symptoms generally develop after age 50, although the disease also affects a small percentage of younger people.

The normal lifetime risk to develop Parkinson's disease for men and women combined is 1.7 percent.

The study is published in the journal Neurology.