Ronald C. Petersen, M.D., Ph.D., is director of the Alzheimer's Disease Research Center at the Mayo Clinic in Rochester, Minn.
Q My father has just been diagnosed with mild cognitive impairment. Will this eventually turn into Alzheimer's disease?
DR. RONALD PETERSEN ADVISES:
A Your father has been diagnosed with mild cognitive impairment (MCI) — a condition that indicates he is more forgetful than we would expect as part of normal aging, but that does not otherwise meet the clinical criteria for dementia or Alzheimer's disease.
Despite significant forgetfulness, people with MCI retain their cognitive skills, such as reading, writing, calculating and problem-solving. And they are still quite functional in most of their daily living activities. But because they do not meet the criteria for dementia, they are in this intermediate zone characterizing MCI.
People with MCI develop Alzheimer's disease more quickly than the general population — at an annual rate of 10 percent to 15 percent, compared to only 1 percent to 2 percent for people without an MCI diagnosis. Within four or five years, half the people with MCI will have developed Alzheimer's; nevertheless, it's likely that most of the rest of them will also develop the disease at some point in the future.
There currently are no approved treatments for MCI, but several clinical trials have recently been completed. The most promising results came from a large trial studying donepezil (Aricept) and high-dose vitamin E. This study found that donepezil reduced the risk of developing Alzheimer's for up to 12 months in participants with MCI compared to those on placebo. However, by the end of the three-year study, there was no difference among people taking donepezil, vitamin E or placebo.
Mild cognitive impairment is an area of active investigation, so we hope therapies will be developed in the near future.