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No impact of surgery on cognitive function: a longitudinal study of middle-aged Danish twins
Unni Dokkedal1, Mette Wod1, Mikael Thinggaard2
1The Unit of Epidemiology, Biostatistics and Biodemography, Danish Twin Registry, Danish Aging Research Center, Department of Public Health, University of Southern Denmark, Odense C, Denmark.
Purpose:
To examine the association between exposure to surgery and 10-year change in cognitive functioning.
Methods:
Among 2351 middle-aged twins, a 10-year change in composite cognitive scores derived from five cognitive tests was compared between 903 (38%) twins exposed to surgery classified as major, minor, knee and hip replacement, and other, and a reference group of 1448 (62%) twins without surgery, using linear regression models adjusted for socioeconomic factors. Genetic and shared environmental confounding was addressed in intrapair analyses of 48 monozygotic and 74 dizygotic same-sexed twin pairs.
Results:
In individual-level analyses, twins with major surgery (mean difference, -0.37; 95% CI, -0.76 to 0.02) or knee and hip replacement surgery (mean difference, -0.54; 95% CI, -1.30 to 0.22) had a tendency of a negligibly higher rate of decline in cognitive score than the reference group. In the intrapair analyses, the surgery-exposed twin had a higher rate of cognitive decline than the co-twin in 55% (95% CI, 45% to 63%) of the pairs. The mean difference in cognitive decline within pairs was -0.21 (95% CI, -0.81 to 0.39).
Conclusions:
No significant associations were found between exposure to surgery and change in cognitive score either in individual-level or in intrapair analyses.
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