By DR. LAURIE HANDWERKER, ABC News Medical Unit

Ritalin, a drug most often used for attention deficit disorders in the very young, may hold promise for a very different set of patients - the predominantly old group of patients who suffer with Alzheimer's.

Apathy - simply put, a lack of interest or motivation - is an under-recognized problem in patients suffering from Alzheimer's disease. Over 70 percent of patients with Alzheimer's suffer from apathy as the illness progresses over the course of five years.

"Often hidden as depression, apathy can significantly impair a person's ability to interact with their loved ones," says Dr. Jacobo Mintzer of the Medical University of South Carolina, lead author of a new clinical trial whose results were presented today at the Alzheimer's Association International Conference in Vancouver, Canada.

The international multi-center study, funded by the National Institute on Aging, looks at using the stimulant medication methylphenidate, commonly known as Ritalin, to treat symptoms of apathy in some patients with Alzheimer's disease.

"No one knows exactly what causes apathy," says Mintzer. "Some data suggests that it is correlated to a decrease in the transmission of dopamine [a chemical] in the brain." The drug Ritalin, which is inexpensive and currently on the market to treat patients with attention deficit disorders (ADD) and narcolepsy, is a compound that enhances the activity of dopamine in the brain.

The trial included 60 patients who had been diagnosed with Alzheimer's disease without depression, and randomized the patients to have treatment with Ritalin or a placebo. Over the six weeks of treatment, the patients receiving Ritalin had significant improvements on their clinical testing for apathy. The side effects were minimal, and included weight loss, anxiety, and headaches.

"While there has been increasing attention on early detection and prediction of Alzheimer's disease, the fact remains that treatment of symptoms, both behavioral and cognitive, is a considerable challenge," says Dr. Alan Lerner, professor of neurology at Case Western Reserve University. "Apathy is one of the most common behavioral problems and is a major cause of caregiver distress and morbidity in Alzheimer's Disease. This study of methylphenidate begins to make significant advances in this direction."

Mintzer stresses that although Ritalin is not a treatment for Alzheimer's Disease, it has promise for the future as an aid for symptom improvement. Larger studies with more patients will be needed to determine the long-term effects before Ritalin can be used as a standard treatment for these patients.

"We don't think we will cure patients, but it will have a positive impact in quality of life of patients and their caregivers," he says.