Researchers say for the first time, a drug seems to slightly delay the progress from memory impairment to Alzheimer's disease.
Previous studies have shown that without treatment, about 10 percent to 15 percent of patients with mild cognitive impairment will progress to Alzheimer's disease each year. However, not every patient with the condition will progress to Alzheimer's.
Researchers compared vitamin E, the Alzheimer's treatment drug donepezil (Aricept), and a placebo for delay or prevention of progression from mild cognitive impairment to Alzheimer's disease. They found vitamin E had no effect, but for a brief time, donepezil reduced the risk of progressing to Alzheimer's when compared to patients who took a placebo.
The average delay in progression was about six months. Even though patients on donepezil progressed to Alzheimer's at a slower rate than those on vitamin E or a placebo, the reduction in risk was short term. By the end of the study, all three treatment groups had the same risk of progression to Alzheimer's disease.
Researchers say they are optimistic that they have now begun to make progress toward delaying the development of Alzheimer's disease and the cognitive decline that accompanies it .However researchers say they are unsure why donepezil's effects dropped off over time. They speculate that either the drug's effect wore off after 18 months or that the drug exerts a modest effect, and then the disease process outweighs the chemical effect of the drug.