Elevated cardiorespiratory fitness and reduced aortic stiffness confer improved cerebral perfusion and memory

Background: Memory is becoming increasingly recognised as one of the most important determinants of overall health status and quality of life, particularly in the geriatric population. Declines in memory with advancing age have been attributed to numerous factors, including an increase in aortic stiffness1, which can be ameliorated with regular exercise training2. Exercise-induced reductions in aortic stiffness have been associated with improved cerebral perfusion and neuropsychological outcome in middle-aged adults3. However, the extent by which a reduction in aortic stiffness impacts cerebral perfusion and memory in older adults has yet to be investigated. 
Methods: Twelve trained (66 ± 4 years; 77 ± 11 kg; ≥150 minutes of aerobic exercise per week) and 12 untrained (67 ± 5 years; 90 ± 8 kg; no formal exercise outside of daily living) healthy aged males from the local community, were recruited into the study based on their incidental physical activity levels. Carotid-to-femoral pulse-wave velocity (cfPWV; applanation tonometry) was used to assess aortic stiffness, in accordance with recommended clinical guidelines4. Middle cerebral artery velocity (MCAv; transcranial Doppler) was recorded continuously during 5 minutes of seated rest to assess cerebral perfusion. Memory was assessed using the free (A1-A5) and cued (A6) recall components of the Rey Auditory Verbal Learning Test (RAVLT), as well as the Repetition of Digits Forwards and Backwards tests. Maximal oxygen consumption (VO_2MAX) was assessed via an incremental exercise test to volitional exhaustion (semi-recumbent cycling) and online expiratory gas exchange. Following confirmation of distribution of normality (Shapiro-W-Wilk Tests), data were analysed using independent sample t-tests. 
Results: By design, the trained participants had a higher VO_2MAX (38 ± 6 vs. 22 ± 3 ml.kg-1.min-1; P < 0.05) and subsequently a lower cfPWV (Figure 1; P < 0.05). Collectively, this translated into improved cerebral perfusion and better memory when assessed using the cued recall component of RAVLT (Table 1; P < 0.05). 
Conclusion: Our findings provide evidence of a link between reduced aortic stiffness, improved cerebral perfusion and ultimately the preservation of memory in older adults. This highlights the importance of maintaining good vascular health as a means of preserving memory with advancing age.