Tooth loss may predict the development of dementia late in life, according to new research. Scientists from the University of Kentucky College of Medicine and College of Dentistry, Lexington, USA, studied data from 144 participants in the Nun Study, a study of ageing and Alzheimer's disease among Catholic sisters of the School Sisters of Notre Dame.

The researchers used dental records and results of annual cognitive examinations to study participants from the order's Milwaukee province who were 75 to 98 years old. The authors found that of the participants who did not have dementia at the first examination, those with few teeth (zero to nine) had an increased risk of developing dementia during the study compared with those who had ten or more teeth.

They proposed several possible reasons for the association between tooth loss and dementia: not only periodontal disease but also early-life nutritional deficiencies, infections or chronic diseases that may result simultaneously in tooth loss and damage to the brain. The study was published in the Journal of the American Dental Association (2007; 138: 1314–1322).