Buying time: management of mild cognitive impairment and early dementia

Early initiation of Alzheimer's disease (AD) treatment is advantageous because it can potentially keep patients in milder stages of the disease longer than delayed treatment. Early initiation of cholinesterase inhibitor therapy is an effective intervention for mild AD. Therefore, it is critical to identify and monitor patients who are at risk for AD and to initiate treatment once AD is diagnosed. A new diagnostic category, mild cognitive impairment (MCI), has been evolving to identify patients who demonstrate objective memory impairment but have essentially intact function or only limited functional impairment and do not meet diagnostic criteria for dementia. The amnestic subtype of this condition is associated with a high risk of AD - 16% of amnestic MCI patients convert to AD each year compared with 1% to 3% of normal elders. A recent three-year study found that patients with amnestic MCI who were treated with donepezil had a significantly reduced likelihood of progression to dementia in the first 12 months of treatment. The effect of donepezil in delaying onset of dementia was supported by significant differences favoring donepezil in the Mini-mental State Examination, the Clinical Dementia Rating-Sum of the Boxes, the Global Deterioration Scale, and the modified Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-Cog) over the first 18 months of treatment. A previous study evaluated the effects of donepezil on memory and cognition in patients with MCI. Although donepezil had no significant effect on memory as measured by the New York University Paragraph Recall Test, it significantly improved scores on the modified ADAS-Cog. Donepezil therefore shows promise in this patient population and warrants further investigation using extended study durations and refined outcome measures.