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Article
May 1992

Decline in Cognitive Performance in Aging Twins: Heritability and Biobehavioral Predictors From the National Heart, Lung, and Blood Institute Twin Study

Author Affiliations

From the Health Sciences Program, SRI International, Menlo Park, Calif (Drs Swan and Carmelli), the Department of Psychiatry and Behavioral Sciences, UCLA School of Medicine (Dr LaRue), the Department of Medical Genetics, Indiana University School of Medicine, Indianapolis (Dr Reed), and the Division of Epidemiology, National Heart, Lung, and Blood Institute, Bethesda, Md (Mr Fabsitz).

Arch Neurol. 1992;49(5):476-481. doi:10.1001/archneur.1992.00530290058012
Abstract

• The present study examined the contribution of genetic factors to Digit Symbol performance and its decline in 23 monozygotic twin pairs (mean age at examination 1, 57.1 years) and 21 dizygotic twin pairs (mean age at examination 1, 56.3 years). These men were assessed twice during a 5-year interval as part of the National Heart, Lung, and Blood Institute Twin Study. The prevalence of decline (a change, >1 SD) during the 5-year interval was 35% and 39% for monozygotic and dizygotic twins, respectively. The pairwise concordance for decline was 45% in monozygotic and 8% in dizygotic twin pairs, suggesting a possible role for genetic factors in the decline in Digit Symbol performance in this sample. A comparison of baseline biologic and behavioral characteristics within monozygotic twin pairs discordant for decline in Digit Symbol performance revealed that decliners had higher initial systolic blood pressures, lower serum cholesterol levels, and lower heart rates than nondecliners.

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