Is There a Multiplicative Adverse Effect of Cardiovascular and Kidney Disease on Neuropsychological Measures?

Abstract

Increasing age is accompanied by increased incidence and comorbidity of various chronic diseases. Many of these conditions, such as cardiovascular and kidney disease, can lead to declines in cognitive functioning. A simple additive effect may be commonly assumed. We here evaluate the hypothesis that such effects may be multiplicative/interactive rather than simply additive, resulting in disproportionate decrements in performance on tests of different cognitive functions. Participants were the 1,782 Canadians aged 65 years and older who completed the clinical assessment of the national Canadian Study of Health and Aging and who were without dementia. Participants were categorized as having either kidney disease, cardiovascular disease, neither, or both. Scores on a measure of verbal fluency showed the predicted interaction effects, but not in the predicted pattern of worst performance in the group with both disorders. Reasons for the relative lack of observed main effects of disease and multiplicative interactions, such as the exclusion of people with dementia and nature of the sample from the community, are discussed.

Key words:

• Canada
• cardiovascular disease
• cognitive impairment
• kidney disease
• older adults

ACKNOWLEDGMENTS

An earlier version of this article was presented in May 2010 at the 10th Global Conference of the International Federation on Ageing, Melbourne, Australia.

Notes

¹Analyses with number of medications used and number of illnesses as additional covariates were also conducted. These gave broadly similar results that are available on request from the first author.