Maine-Syracuse Longitudinal Study investigators publish three new studies with implications for blood pressure measurement and control of diabetes mellitus.
University of Maine investigators in the Laboratory of Epidemiology, Cardiovascular Disease, Aging and Neuropsychology, Graduate School of Biomedical Science and Engineering (GSBSE), published three new studies on blood pressure and diabetes. The laboratory employs data from the Maine-Syracuse Longitudinal Study (MSLS), a 35-year study of relations between cardiovascular disease and cognitive function (https://umaine.edu/psychology/faculty/merrill-f-elias/msls-description/).
1. Torres RV, Elias, MF, Crichton GE, Dore G, Davey A, Systolic orthostatic hypotension is related to lowered cognitive function: findings from the Maine-Syracuse Study. Journal of Clinical Hypertension. 2017; doi: 10.111/jch.13095.
In some individuals, standing causes a shift in blood volume that can lead to postural hypertension (abnormal rise in blood pressure) or postural hypotension (abnormal fall in blood pressure) when the body’s control mechanisms (autoregulation) are not functioning properly. Both conditions have been associated with poor health outcomes, including reduced cognitive function. However, few studies have used more than one or two cognitive tests, have employed community-dwelling individuals and have blinded the participants and the investigators to the orthostatic testing procedure during data collection. Led by Rachael Torres (University of Delaware), the MSLS study team examined relations between postural hypertension, postural hypotension and cognitive function for six major cognitive domains with adjustment for demographics and cardiovascular risk factors.
In a sample of 961 community-dwelling individuals, orthostatic hypertension was not related to any of the cognitive measures. However, participants who exhibited postural hypotension due to an abnormal reduction in systolic blood pressure had lower Global composite, Verbal Memory and Scanning and Tracking domain scores compared with those who had normal systolic blood pressure change. From a practical standpoint, orthostatic hypotension is not always symptomatic and can go undetected in the absence of proper blood pressure assessment. The American Heart Association recommends assessment of recumbent followed by standing blood pressure, although it is common for assessment to be restricted to sitting blood pressure values. Considering the poor health outcomes associated with orthostatic hypotension, it is important that this practice is changed.
2. Dore GA, Elias MF, Crichton GE, Robbins MA. Age modifies the relation between intra-individual measurement to measurement variation in blood pressure and cognitive functioning: the Maine-Syracuse Study. Journal of Hypertension. 2017; doi: 10.1097/HJH.0000000000001510.
In many studies, intra-individual variation in BP at a single occasion or over time has been a stronger predictor of lowered cognitive functioning than chronically elevated blood pressure. But few, if any, studies have examined the important role of age in the adverse impact of higher variability in blood pressure on cognitive functioning. Led by Gregory Dore (National Institute on Aging), MSLS investigators examined the role of age in the adverse influence of higher variability in blood pressure on cognitive functioning in 980 men and women (mean age=62 years, SD= 12.8). This community-based sample was free of dementia, acute stroke and serious kidney disease. Intra-individual blood pressure variability at a single measurement occasion was a stronger predictor of lowered cognitive ability than chronically elevated blood pressure. Systolic blood pressure variability was associated with lower levels of performance in the domains of Verbal Memory, Visual-Spatial Memory and Organization, Scanning and Tracking and Abstract Reasoning with statistical adjustment for demographics and cardiovascular risk factors. However, associations between variability in systolic blood pressure and lowered cognitive test performance increased in magnitude with advancing age. Persons over 60 years of age were clearly more vulnerable to lowered cognitive performance in relation to higher blood pressure variability than adult participants less than 60 years of age. In order to recognize variability in blood pressure, office visits should include more than the standard one to two blood pressure measurements. The team has advance arguments for multiple blood pressure assessments at each office visit (at least 5) in previous editorials in Hypertension and the American Journal of Hypertension.
3. Elias MF, Crichton GE, Dearborn PJ, Robbins MA, Abhayaratna WP. Associations between type 2 diabetes mellitus and arterial stiffness: a prospective analysis based on the Maine-Syracuse Study. Pulse. 2017;5:88-98.
The MSLS study team and other investigators have reported that lowering of cognitive performance in persons free from dementia and acute stroke history is observed in the presence of diabetes mellitus. Led by Merrill (Pete) Elias (University of Maine), this investigation was designed to see if diabetes recognized (diagnosed) 5 years earlier in adult life is associated with increased arterial stiffness at follow-up. Pulse wave velocity is the gold standard, non-invasive method of measuring stiffness in the arteries. Results of this investigation indicated that all treated but uncontrolled Type II diabetic individuals (n= 52) had three-fold greater risk for increased arterial stiffness than those with no diabetes (n=456). Further, participants with uncontrolled diabetes over a 4- to 5-year period (n=34) had nine-fold greater risk than non-diabetic participants. This was true despite control for demographic variables, cardiovascular risk factors and cardiovascular events such as stroke and heart attack. Early recognition and treatment of diabetes is important for a healthy heart and healthy brain. Further studies are underway to see if arterial stiffness is a mediator (intermediate variable) in the relation between diabetes and lower cognitive performance.
Professors Merrill F. Elias and Michael A. Robbins are at the University of Maine, Department of Psychology and GSBSE. Walter P Abhayaratna is a professor of Cardiovascular Medicine at the University of Australia. Georgina E. Crichton is at the University of South Australia. Rachel V. Torres and Adam Davey are at the University of Delaware. Gregory A. Dore is a postdoctoral fellow at the National Institute on Aging, Baltimore. Rachael Torres and Gregory Dore both received degrees in psychology from the University of Maine; Rachel Torres received a BA in 2015 and Dore a PhD in 2013. Peter Dearborn is a PhD candidate in psychology at the University of Maine and a GSBSE student affiliate. MSLS data collection was supported by the National Heart, Lung and Blood Institute and the National Institute on Aging (NIH) and manuscript preparation was supported by various national grants awarded to co-investigators.