DEAR DR. DONOHUE: My 9-year-old grandson has attention-deficit disorder. He takes Ritalin. I am fearful that it might damage his brain or set him up for drug addiction later in life. Is Ritalin a harmful drug? How does it work? – L.A.

ANSWER: Attention-deficit hyperactivity disorder – ADHD – is something that was not diagnosed when we were children. It existed then but was not recognized as being a treatable condition. Now there are criteria that establish its diagnosis, and now there are treatments that help many children contend with it successfully. Input from parents, teachers, doctors and mental health experts is needed before a diagnosis is made and before treatment is begun. The label should not be given to children without the consensus of all these people in order to prevent overdiagnosis and unnecessary treatment.

Children with ADHD find it impossible to sit quietly for more than a few minutes. Their concentration is fleeting. Rarely are they able to complete assigned tasks. They are not learning-impaired, but their grades often do not reflect their true intellectual ability because their impulsiveness and constant turmoil make it difficult for them to excel in school.

Ritalin is the most frequently prescribed drug for ADHD. It keeps norepinephrine, a messenger brain chemical, adequately supplied to brain cells and to regions of the brain that must be activated to keep attention focused on the task at hand. Response to Ritalin is extraordinary. Close to 75 percent of ADHD children respond favorably to it. A new drug, Strattera, is available for children who do not benefit from Ritalin.

Ritalin doesn’t harm the brain, and there is no evidence yet that Strattera does. They do not predispose treated children to drug addiction in later life. In fact, ADHD children who take Ritalin have lower rates of addiction than ADHD children who go untreated.

DEAR DR. DONOHUE: Please do me a favor. Repeat your recipe for relieving constipation. I tried it for a week and got good results. Unfortunately I have misplaced the directions. I suspect others must be in the same boat. – A.T.

ANSWER: I’ll give directions again, but then I have to let the recipe rest. Another mention would be overkill.

The mixture consists of 2 cups of Miller’s bran (the kind found in health food stores), 2 cups of applesauce and 1 cup of prune juice, sweetened or unsweetened. Refrigerate the concoction and take 2 or 3 tablespoons twice a day. Feel free to add anything you want — nuts, fruits or your favorite spices — but don’t omit the three basic ingredients. I am not the author of this recipe. If I knew who was, I’d give that person full honors.

Constipation is a problem that afflicts a sizable number of people. Readers who would like more information on the subject and its treatment can order a copy of the pamphlet on that topic by writing: Dr. Donohue – No. 504, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: When I sit, I have a most uncomfortable feeling at the base of my spine. My doctor says it is my coccyx. What is that? He has me sitting in a tub of warm water twice a day and has me taking Aleve. Neither works. What else can be done? – T.M.

ANSWER: Four small, fused bones at the very tail of the spine make up the coccyx (KOK-six). Its function is puzzling. However, it can become a source of pain. Slipping and falling on the coccyx is one way to get it to act up. Most often, however, it begins to hurt without a known cause.

Get a 3-inch-wide belt and cinch it around yourself under your clothes at midbuttock level. Wear it as much as feasible, including at night. It creates a natural cushion for the coccyx and relaxes the pull of ligaments on it. If the pain hasn’t gone by three months, see an orthopedic doctor. This diagnosis needs to be confirmed.

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.