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.

The cognitive test battery will consists of the tests listed below, administered in the order given.

1. Digit Span
2. California Verbal Learning Test
3. Symbol Digit Modalities Test
4. Letter Number Sequencing
5. California Verbal Learning Test Delay
6. Paced Auditory Serial Addition Test
7. D-KEFS Verbal Fluency
8. D-KEFS Color-Word
9. WASI Vocabulary
10. WASI Matrix Reasoning

Eligibility Criteria:
Inclusion Criteria:

SCI

* Between the ages of 25 and 49 years old
* Duration of injury must be between 5 and 10 years
* AIS grade of A or B
* Non-ambulatory (wheelchair dependent)
* At least 20/60 minimum acuity in worst eye on the Snell Eye Exam
* A score ≥24 on the Montreal Cognitive Assessment
* English literate
* Able to provide informed consent

Age-matched non-SCI

* Between the ages of 25 and 49 years old
* At least 20/60 minimum acuity in worst eye on the Snell Eye Exam
* A score ≥24 on the Montreal Cognitive Assessment
* English literate
* Able to provide informed consent

Older non-SCI

* Between the ages of 55 and 65 years old
* At least 20/60 minimum acuity in worst eye on the Snell Eye Exam
* A score ≥24 on the Montreal Cognitive Assessment
* English literate
* Able to provide informed consent

Exclusion Criteria:

* Acute illness or infection
* Documented history of:
* Controlled or uncontrolled hypertension or Diabetes mellitus
* Recent illicit drug abuse (from medical chart, within the past 6-months)
* Epilepsy or seizures
* Neurodegenerative disease including Alzheimer's disease, Parkinson's disease, Dementia, Stroke, Multiple sclerosis
* Severe TBI (identified by TBI screening tool)
* Any significant history of psychiatric disease/disorders:
* Post-traumatic stress disorder
* schizophrenia
* Bipolar disease
* Substance abuse or dependence within the past 6 months

MRI has additional exclusion:

* Subject has been informed that it is medically unsafe to receive a regular MRI as part of my medical care
* Pregnant
* Right handed
* Prone to claustrophobia
* Metal in body including:
* metal fragments or pieces in subject's eye or any other part of body
* brain stimulators
* pacemakers, or other implanted electrical devices or pumps
* aneurysm clips
* metallic prostheses (including metal pins and rods, heart valves)
* internal hearing aids
* permanent eyeliner
* shrapnel fragments
* piercing that cannot be taken out