Alzheimer's drug may work for other type of dementia

From 15% to 25% of dementia cases in the elderly involve Lewy bodies--spherical deposits that form in brain cells. The deposits are markers of Parkinson's disease, but they also can develop in people without the illness.

Symptoms of Lewy-body dementia include depression, attention deficits, hallucinations and mental impairment that comes and goes. These people also can have Parkinson's disease-like symptoms, such as a shuffling gait, a flexed posture and relatively rarely, tremors.

Based on previous research showing that people with this form of dementia experience impairments in a brain messaging system called the cholinergic system, a team of researchers led by Dr. Ian McKeith, of the University of Newcastle upon Tyne, UK, decided to test a type of Alzheimer's drug that targets this system.

In a study of 120 people with dementia with Lewy bodies, patients treated with the cholinesterase inhibitor rivastigmine (Exelon) experienced greater relief of symptoms than those who received a placebo, which did not contain any medication.

After 20 weeks of treatment, symptoms had improved at least 30% in about 63% of patients taking rivastigmine, compared with 30% of those in the placebo group, the researchers report in the December 16th issue of The Lancet. The treatment group was not only less anxious and apathetic than the placebo group, but also experienced fewer hallucinations and delusions.

The benefits of the drug wore off once patients stopped taking it, however.

The results of the study suggest that cholinesterase inhibitors like rivastigmine may be more effective than a class of drugs called neuroleptics currently used to treat hallucination and behavioural problems, McKeith's team concludes.

Dr. Jeffrey L. Cummings, of the University of California at Los Angeles, notes in an accompanying editorial that patients with Lewy-body dementia are "exceptionally sensitive" to neuroleptics, which may profoundly worsen their Parkinson's disease-like symptoms.

"Thus for them rivastigmine looks like a step forward," he writes. But patients taking the drug should be carefully monitored, according to Cummings, since the drug is known to cause weight loss and gastrointestinal side effects.

In the study, nausea, vomiting and anorexia were all more common among patients taking rivastigmine than among those taking the placebo.

Several of the researchers involved with the study are employed by Novartis Pharmaceuticals, the maker of rivastigmine.