Introduction:
Cardiovascular diseases have been associated with impaired cognitive performances, especially in functions. In contrast, it is clearly established that regular physical activity maintained throughout life protects against age-related cognitive decline.
Purpose:
to assess maximal oxygen uptake (VO2max), cardiac output, and cerebral hemodynamic changes, assessed by Near-Infrared Spectroscopy (NIRS), during a graded maximal exercise tests, and cognitive performance at rest in patients with stable coronary heart disease (CHD) and healthy matched adults.
Methods:
Ten stable CHD patients (67.1±10.5 years) and 9 age-matched controls (62.2± 11.4 years) were included in this pilot study. Measurements included: body composition (bioelectrical impedance), complete blood analysis in a fasting state, cognitive performance using validated neuropsychological tests, graded maximal exercise testing on ergocycle with gas exchange analysis, non-invasive cardiac output measurement (cardiac bioimpedance) and NIRS signals measurement at the left prefrontal brain level (oxyhaemoglobin: O2Hb, deoxyhaemoglobin: HHb ; total haemoglobin: THb, and differential haemoglogin: Hbdiff).
Results:
Several cognitive performance items were lower in the CHD group, especially regarding executive functions (Backward digit span score, p<0.05; trail making test B, p=0.05; Stroop test (inhibition/flexibility), p<0.05). There was no difference between CHD and controls in VO2 max (29.7±8.5 Vs 32±6.3 ml/kg/min) and maximal cardiac output (15.5±3.9 Vs 17±2.6 l/min), whereas cardiac output and cardiac index at the ventilatory threshold were lower in CHD (5.75±1 Vs 7.06±0.6 l/min/m2, p<0.05, and 11.2±2.2 Vs 14.1±2.8 l/min, p<0.01, respectively). There was a significant difference in the kinetics of NIRS signal with higher amplitude for CHD patients vs. controls for O2Hb (p<0.01); THb (p<0.05) and Hbdiff (p<0.05). Significant higher amplitude were also found for O2Hb, THb, Hbdiff (p<0.0001) in younger (62 years) participants. HHb (p<0.0001) and Hbdiff (p<0.01) amplitude was higher for fit (≥120% theoretical VO2max) vs. less fit (<120%) participants.
Discussion:
Compared to age-matched controls, our sample of stable fit CHD patients had a comparable maximal exercise tolerance and cardiac output, with higher NIRS cerebral signals amplitude for O2Hb, THb and Hbdiff. This latter parameter thus does not seem to influence cognitive performance at rest, that was lower in CHD patients, especially in executive functions. However, an important inter-individual variability of cerebral NIRS signal amplitude was observed, with age and fitness appearing as major contributors. We plan to recruit a larger sample of subjects to assess more clearly relationships between exercise, tolerance hemodynamic parameters and cognitive performance.
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