Impact of Age on Cardiovascular, Cerebrovascular and Cognitive Health in Spinal Cord Injury

As the spinal cord injured population ages, these individuals are being exposed to an increased prevalence of age-associated diseases, which coupled with the secondary complications of the injury may contribute to the reduced life expectancies. Decentralized autonomic regulation in persons with SCI results in a multitude of cardiovascular changes, which may contribute to accelerated aging. Adverse cardiovascular changes may have deleterious effects on cerebral blood flow dynamics and an increase in cerebral vascular resistance index in individuals with SCI during cognitive testing. Deficits in memory and processing speed in individuals with SCI may relate to cardiovascular and cerebrovascular dysfunction. Identifying the associations between healthy aging versus premature or accelerated aging in organ system function in the SCI population is an important first step towards prevention and amelioration of these changes. Therefore the study objectives are to compare, among individuals with SCI, age-matched non-SCI and older non-SCI individuals arterial stiffness and cerebral vascular resistance index; memory, processing speed, and executive function; and volume of white matter hyperintensities. 60 individuals with SCI, 30 age-matched non-SCI controls, and 20 older non-SCI controls will be recruited for this study. All potential subjects will undergo a two-part screening process which consists of an initial screening via telephone and a detailed, in-person screening. Eligible subjects will be invited to participate in a 4 hour laboratory visit during which their arterial stiffness, blood pressure, heart rate, respiration rate and, blood flow to the brain will be monitored at rest and during a comprehensive series of cognitive tests. A subset of the participants will be asked to take part in an MRI brain imaging session: 40 persons with SCI, 10 age-matched non-SCI and 10 older non-SCI. Eligible subjects will be asked to participate in a 1 hour MRI/functional magnetic resonance imaging(fMRI) session.

We hypothesize that arterial stiffness and cerebral vascular resistance index will be increased in the SCI group compared to the age-matched non-SCI but will be comparable to the older non-SCI groups. In addition, we hypothesize that the prevalence of mild to moderate cognitive impairments in memory, processing speed, and executive function will be increased in the SCI individuals compared to the age-matched non-SCI but will be comparable to the older non-SCI individuals.