Differences in cognitive functioning and haemodynamic outcomes between individuals with chronic spinal cord injury and non-injured controls: Hypotensive underpinnings

This study: (1) compared haemodynamic and cerebrovascular responses to an orthostatic challenge between individuals with a chronic (>1-year) cervical or upper-thoracic spinal cord injury (SCI) and non-injured controls, and examined whether these responses were associated with cognitive performance, and (2) explored whether habitual free-living blood pressure (BP) disturbances were associated with lower cognitive functioning. Thirteen individuals with SCI and 13 age- and sex-matched non-injured controls were recruited. Participants completed a motor-free neurocognitive test battery assessing working memory, attention/concentration/psychomotor speed, verbal fluency, and executive function. Laboratory assessments included a 20-min head-up tilt test with beat-by-beat cardiovascular and cerebrovascular monitoring, followed by 24-h ambulatory BP monitoring to capture free-living BP instability. After controlling for numerous confounders of cognition (i.e., age, education, weight, waist circumference, physical activity, depression, and traumatic brain injury), individuals with SCI performed worse in the executive function domain relative to the non-injured controls. Individuals with SCI exhibited lower resting BP and a greater degree of orthostatic hypotension, along with more hypotensive events in the 24-h free-living period, compared to the non-injured controls. These laboratory and free-living haemodynamic observations resulted in significant, moderate-to-large associations with performance in multiple neurocognitive assessments. Collectively, these exploratory findings indicate that both transient (i.e., orthostatic stress) and resting hypotension are linked with lower cognitive functioning following SCI, with comparable associations between laboratory and free-living environments. Given that the cumulative burden of systemic hypotension likely contributes to this cognitive impairment, future research should identify interventions capable of stabilising autonomic cardiovascular function to mitigate long-term neurocognitive decline.