Dementia is a severe deterioration or loss of intellectual faculties that may be accompanied by emotional disturbances and personality changes. The development of dementia is a common concern of older Americans due to fears of disability, loss of independence, and the subsequent burden on caregivers. Cognitive impairment is a condition that is not as severe as dementia, but still contributes to a decrease in quality of life and an increase in health care costs.

Until recently, there were no population-based estimates of the number of people in the United States affected by cognitive impairment, which increases the risk of progression to dementia. In a recent issue of the Annals of Internal Medicine, investigators reported that, in 2002, an estimated 5.4 million people in the United States aged 71 years or older had cognitive impairment without dementia. This is far more than the estimated 3.4 million individuals in the same age group who were diagnosed with dementia.

Of the individuals studied who had cognitive impairment without dementia, the annual death rate was 8% and the rate of progression to the threshold of dementia was 12%. There were many causes for cognitive impairment, including pre-Alzheimer's states, stroke, and other chronic medical conditions. The authors of the study suggested that focusing on prevention strategies, such as stroke prevention and reduction of cardiovascular risk factors, might reduce the prevalence of cognitive impairment without dementia and benefit public health in our aging society.