Cognitive functional status of age-confirmed centenarians in a population-based study.

The New England Centenarian Study is a population-based study of all centenarians in 8 towns near Boston, MA. Age was confirmed for 43 centenarians all alive on a designated date. To determine prevalence of dementia in centenarians, the authors analyzed neuropsychological, medical, and functional status data for 34 (79%) of the centenarians. Definition of dementia was based on the Consortium to Establish a Registry for Alzheimer's Disease criteria, and a Clinical Dementia Rating (CDR) score was formulated for each participant. Seven (21%) had no dementia (CDR score 0), and an additional 4 (12%) were assigned a CDR score of 0.5, uncertain or deferred diagnosis. The remaining 22 (64%) had at least some degree of dementia. The authors calculated Barthel Index scores to determine ability to perform activities of daily living. There was a statistically significant correlation between CDR scores and Barthel Index scores (r = -0.73). Correlation was strongest for those with no or severe dementia, with the greatest range of function measured among those with moderate dementia.