Nuns Provide Key Insight on Aging: Oral Health and Dementia

A recent finding of the Nun Study identifies oral disease as a potential risk factor for dementia, with conclusions indicating that a low number of teeth — fewer than ten — may be an accurate predictor of dementia in later life. Furthermore, the study showed that subjects with the fewest number of teeth presented with the most severe incidence of dementia.

Funded by the National Institute on Aging as well as a number of private foundations, the Nun Study is an endeavor of the Sanders-Brown Center on Aging at the University of Kentucky Chandler Medical Center intended to further research on Alzheimer’s disease and other diseases and disorders associated with the aging process. Many, if not most, studies of aging have historically focused on middle-aged, white males, and the Nun Study provides an opportunity to study women exclusively. Limitations in studies on Alzheimer’s patients often include the inability of subjects to recall information about earlier life choices and arrangements. The Nun Study is uniquely able to compensate for this probability with the contents of the convent archives, which provide records about birthplace, family history, as well as autobiographies written in mid-lives. Additionally, the sisters provide a number of built-in control factors: they live very similar lifestyles, including not smoking, drinking very little if at all, and all have similar housing, marital and reproductive statuses, occupations (approximately 85% of the sisters are or were teachers), and have similar access to health care.

The participating nuns are Roman Catholic sisters from the School Sisters of Notre Dame drawn from seven religious provinces across the United States. The 678 participants have all pledged to donate their brains to the study upon their deaths, as post-humus examination of the brain allows the researchers to accurately determine whether Alzheimer’s disease was indicated pathologically. This information is coupled with clinical indicators, such as memory loss, impairment in language, and/or impairment in social functioning to support a positive diagnosis of Alzheimer’s disease. The subjects were all between the ages of 75 and 102 when the study began. Each year, the participants are assessed in terms of cognitive and physical function, and submit to medical exams and blood tests which look at genetic and nutritive factors in aging.

The study identifying a link between oral health and dementia is only the most recent finding to be published out of the Nun Study. Other investigations have provided important information about Alzheimer’s disease and aging. One study provided a definitive neuropathological method to distinguish Alzheimer’s patients from control patients. Another utilized autobiographies gleaned from the convent archives which were written by the subjects at the age of 22. This study showed that a lower measure of linguistic ability demonstrated at this early age was correlated with higher degrees of impairment, cerebral atrophy, and clinical diagnosis of Alzheimer’s disease.

Reference

Stein, P., Desrosiers, M., Donegan, S., Yepes, J., and Kryscio, R. (2007). Tooth loss, dementia and neuropathology in the Nun Study. Journal of the American Dental Association , 138, 1314-1322.

Link to the Nun Study Web site.