From blood pressure to physical disability: the role of cognition.

We examined the hypothesis that lowered cognitive performance plays a role in the relation between elevated blood pressure and physical disability in performing basic physical tasks. A community-based sample (N=1025) free from stroke and dementia (mean age: 61.1 years; SD: 13.0 years; 59.8% women) was used. Using path analysis, systolic and diastolic blood pressures (predictor variable) measured over multiple longitudinal examinations were averaged and related to multiple measures of cognition (intermediate variable) and physical ability (PA; outcome variable) measured at wave 6 of the Maine-Syracuse Study. PA was indexed by time required to execute standing, walking, and turning tests. A best-fit path model including blood pressure and multiple demographic and cardiovascular disease covariates was used. Paths from systolic blood pressure to global performance, verbal memory, and abstract reasoning (Similarities test) were significant (P<0.05), as were paths from diastolic blood pressure to global performance, executive functioning, visual spatial organization/memory, verbal memory, working memory, and abstract reasoning. Regardless of the blood pressure predictor, lower cognitive performance (intermediate variable) was related to lower PA (outcome) in the path from blood pressure to PA. The direct path from blood pressure to PA was significant only for systolic blood pressure. Cognitive performance mediates between blood pressure and PA. As compared with systolic blood pressure, more domains of cognitive functioning intervene between diastolic blood pressure and PA.