DEAR DR. DONOHUE: What causes Parkinson’s disease? Would someone under a lot of stress be more likely to become afflicted with it?

What are the best options for treatment? How long do most people live after being diagnosed with it? – R.J.

ANSWER: Parkinson’s disease has many causes, but in truth, most Parkinson’s patients cannot be given a definite cause for their illness. In some people, particularly those who develop it at a young age, genes are a major factor. Repeated head trauma, such as a boxer might suffer, is another cause. Carbon monoxide poisoning has been cited as a cause. Stress? I don’t know. I have never seen it listed as a cause, but stress can make the body vulnerable to many disorders.

Even when the cause is unknown, what happens to the brains of people with Parkinson’s is known. Their brains become depleted of an important brain chemical, dopamine, and of the cells that produce that chemical. All Parkinson’s symptoms are attributed to the dopamine shortage. Those symptoms are trembling hands when they are resting, a shuffling walk consisting of small steps, a slowness of all movement, the tendency to fall and a rigidity of muscles.

The best treatment is the one that works for an individual patient. Sinemet is a favored medicine. It supplies the missing dopamine messenger to the brain. Tasmar and Comtan are also popular. They prevent the degradation of what little dopamine there is, and, in time, that increases the brain’s supply of it. Requip and Mirapex are two medicines that have an action that mimics the action of dopamine.

For most Parkinson’s patients the disease progresses slowly. It can take 15 or more years before patients have significant disability. Most patients have a normal life span.

DEAR DR. DONOHUE: Is there really a connection between cholesterol and heart disease? Recently my wife and I had electron-beam tomography to detect plaque buildup in coronary arteries. My results showed significant buildup, but my cholesterol is only 184 mg/dL (4.7 mmol/L). My wife’s arteries are free of buildup, but her cholesterol is above 300 (7.8). What gives? – E.G.

ANSWER: Some background information for readers is needed. A normal cholesterol reading is 200 mg/dL (5.2 mmol/L) or lower. Electron-beam tomography is a new and special kind of scan that takes such sharp pictures that a buildup of calcium and plaque on heart artery walls can be seen.

I understand your sense of injustice. How could you, with a lower-than-normal cholesterol, have buildup on the walls of your heart’s arteries? The reason lies in a little-appreciated fact that there are forces other than cholesterol responsible for clogging arteries.

Do not take that to mean that cholesterol is not an important factor. It definitely is, and it has been proven to be so time and again. Who knows what might have happened to you if your cholesterol had been higher? You might have had a heart attack, because there are, without a doubt, other contributing causes of plaque buildup, and you must have some of those.

It is sobering to note that a large percentage of people who have had a heart attack also have had normal cholesterol readings.

For the story on heart artery disease, readers can order the pamphlet on that topic by writing to: Dr. Donohue – No. 101, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6.50 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I am a 35-year-old mother of two who has been on birth control pills for about 17 years. Someone made a comment to me that taking the pill causes cancer. Does it? – Anon.

ANSWER: If birth control pills cause cancer – breast cancer in particular – we would have seen headlines screaming that information. We don’t, because most studies show no relation between cancer and pill use.

DEAR DR. DONOHUE: I am trying to cope with cellulitis. I have begun taking an antibiotic, but it does not seem to be working. Should I ask for a change of medicine? How did I get this? – A.S.

ANSWER: Cellulitis is an infection of skin cells and of the tissues beneath the skin cells. The cause is usually a strep or staph germ.

Once the germ gains entry into the skin, it spreads rapidly. The skin turns red and feels warm. It also hurts.

People get this infection when a minute scratch of the skin allows the germ to penetrate the usual skin barriers that protect us from infections. Athlete’s foot is another way that germs can enter skin cells. The ragged skin of athlete’s foot provides an open door for germ invasion.

How long have you been taking the medicine? If it’s only been a day or so, you will not see much improvement. If, by the third day, the infection is not calming down, let the doctor know. Or if the infection appears to be spreading after beginning antibiotic therapy, let the doctor know — even sooner.

You chose a good word to describe a battle with this infection — “coping.” There is not a whole lot a person can do to hasten healing, other than take the prescribed antibiotic.

Cellulitis is not cellulite. Cellulite is skin dimpling over fat deposits.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.