Salivary sIgA and cortisol: markers for functional dependence in older adults

Elderly persons with health problems and physical limitations have reduced independence. Since poor functional ability is a known risk factor for disease among older populations, including oral disease, this study was undertaken to assess whether salivary defense factors and the stress hormone cortisol are significant markers for functional dependence. Oral examinations; salivary and microbial analyses; and interviews using the Activities of Daily Living (ADD index, the Mini Nutritional Assessment (MNA) and the Perceived Life Stress Questionnaire (PLSQ) were conducted for 123 dentate subjects. Of the subjects, 80 lived independently in the community or in apartments at the Baycrest Centre for Geriatric Care in Toronto, Canada, and 43 resided in the Baycrest nursing home or the Baycrest Hospital. Whole saliva samples were assayed for total secretory immunoglobulin A (sIgA), sIgA1, sIgA2, total protein and cortisol using ELISA. Dependent residents in the nursing home/hospital scored significantly lower in the nutritional assessment, had higher mean PLSQ scores, increased total protein and cortisol concentrations, and reduced salivary flow rates in comparison to ambulatory residents in the community/apartments. In multivariable logistic regression, factors associated with functional dependence were: being male, perceiving income as inadequate, having low salivary flow rate and drinking less than 5 cups of water per day. These results indicate that salivary flow and cortisol may be useful markers of functional dependence; however, the ability of these markers to predict functional decline cannot be confirmed until longitudinal studies are conducted.