Isometric exercise training for managing vascular risk factors in mild cognitive impairment and Alzheimer's disease

Dr Nicole Catherine Lincoln Hess¹ – BPsych (Hons)., PhD

Professor Neil Andrew Smart¹- BSc (Hons)., M.Med., PhD

¹School of Science and Technology, University of New England, Armidale, NSW 2350, Australia

Presenter: Dr Nicole Catherine Lincoln Hess¹ – BPsych (Hons)., PhD

Abstract

Pathological changes to the cerebral microvasculature precede and/or accompany vascular disorders such as hypertension, neurovascular disorders such as AD, and cognitive decline. Individuals with a history of vascular risk factors (VRF’s) and vascular disease are considered high risk candidates for developing cognitive impairment in later life. Evidence suggests that vascular injury exacerbates the severity of dementia in AD and that the neurodegenerative process is heavily driven by vascular factors.

Data from recent analyses suggests that isometric exercise training (IET) may improve vascular integrity and elicit blood pressure reductions in hypertensives greater than those seen with dynamic aerobic and resistance exercise. Unlike aerobic exercise, the effects of IET on cognitive performance have not been investigated. Supporting a proposition that IET performed by elderly individuals might promote healthy neural functioning and boost cognitive performance are the same principles that support the efficacy of remote ischemic conditioning (RIC) and physiological ischemic training (PIT).

Ischemic conditioning of a healthy limb to stimulate endogenous protective pathways to support and improve the healthy functioning of distant organs such as the kidneys, heart and the brain has been successfully demonstrated through blood restriction techniques such as remote ischemic conditioning (RIC) and physiological ischemic training (PIT).

Originally ischemic conditioning was developed as a cardio protective technique for patients with cardiovascular arterial disease and myocardial ischemia, however, current research demonstrates that similar to the heart, the brain can also be conditioned with ischemia and hypoxia. RIC has been demonstrated to stimulate endogenous neuroprotective pathways and increase cerebral blood flow. Mouse models of vascular cognitive impairment show that when compared to the control cohort, RIC resulted in less inflammation, less β-amyloid deposition, reduced white and grey matter damage, increased cerebral blood flow and improved cognition. Furthermore, RIC has also been implicated in enhancing neuroplasticity.

PIT is a technique whereby skeletal muscle is subjected to intense contraction via isometric contraction or tourniquet in order to stimulate physiological ischemia. In clinical trials, PIT using isometric handgrip exercise performed by patients with coronary artery disease and a coronary artery occlusion significantly increased collateral blood flow in the myocardium. Unlike RIC, the efficacy of PIT to neural applications has not yet been investigated.

1. 
   We aim to raise awareness of the role that blood restriction techniques and therapies play in the enhancement and reparation of the circulatory system, including the cerebral vascular system, and the potential role of these applications in neurodegenerative disease. Attendees will learn of the current state of research in ischemic therapy with a specific focus on isometric exercise training (IET) as a therapeutic treatment for chronic disease.
   
2. 
   Attendees will learn of both the feasibility of IET as a therapeutic intervention for neurodegenerative disease and the current gap in the IET research paradigm to investigate this application.
   
3. 
   There are several different branches of science that can contribute to future research in this direction. The research we present is cross-disciplinary in nature and exploits a marriage between psychology, sports science, human biology and physiology, and neuroscience.
   

4. 
   Isometric exercise is an easy and cost effective therapy making it attainable and viable in all research, clinical and aged care settings.
   
5. 
   Against the backdrop of unprecedented and pervasive global population aging, our presentation contains numerous promising opportunities for future research activities into the understanding, treatment, and prevention of dementia. Furthermore, future studies suggested by our presentation to address identified gaps in the literature can easily be positioned to align with national research priorities for improving the quality of life in our aging population.
   

Dr Hess is an early career researcher having completed a PhD in science and psychology. She was awarded the Chancellors Doctoral Research Medal for this work. Previously, Dr Hess completed a degree in Psychology with honours.