Department of Physiology, University of Otago, Dunedin, New Zealand.
Exp Gerontol. 2012 Aug;47(8):541-51. doi: 10.1016/j.exger.2011.12.002. Epub 2012 Jan 2.
Regular exercise improves the age-related decline in cerebral blood flow (CBF) and is associated with improved cognitive function; however, less is known about the direct relationship between CBF and cognitive function. We examined the influence of healthy aging on the capability of acute exercise to improve cognition, and whether exercise-induced improvements in cognition are related to CBF and cortical hemodynamics. Middle cerebral artery blood flow velocity (MCAv; Doppler) and cortical hemodynamics (NIRS) were measured in 13 young (24±5 y) and 9 older (62±3 y) participants at rest and during cycling at 30% and 70% of heart rate range (HRR). Cognitive performance was assessed using a computer-adapted Stroop task (i.e., test of executive function cognition) at rest and during exercise. Average response times on the Stroop task were slower for the older compared to younger group for both simple and difficult tasks (P<0.01). Independent of age, difficult-task response times improved during exercise (P<0.01), with the improvement greater at 70% HRR exercise (P=0.04 vs. 30% HRR). Higher MCAv was correlated with faster response times for simple and difficult tasks at rest (R(2)=0.47 and R(2)=0.47, respectively), but this relation uncoupled progressively during exercise. Exercise-induced increases in MCAv were similar and unaltered during cognitive tasks for both age groups. In contrast, prefrontal cortical hemodynamic NIRS measures [oxyhemoglobin (O(2)Hb) and total hemoglobin (tHb)] were differentially affected by exercise intensity, age and cognitive task; e.g., there were smaller increases in [O(2)Hb] and [tHb] in the older group between exercise intensities (P<0.05). These data indicate that: 1) Regardless of age, cognitive (executive) function is improved while exercising; 2) while MCAv is strongly related to cognition at rest, this relation becomes uncoupled during exercise, and 3) there is dissociation between global CBF and regional cortical oxygenation and NIRS blood volume markers during exercise and engagement of prefrontal cognition.
定期运动可改善与年龄相关的大脑血液流量（CBF）下降，并与认知功能改善相关；然而，关于 CBF 与认知功能之间的直接关系知之甚少。我们研究了健康衰老对急性运动改善认知能力的影响，以及运动引起的认知改善是否与 CBF 和皮质血液动力学有关。在 13 名年轻（24±5 岁）和 9 名老年（62±3 岁）参与者中，在休息时和在以 30%和 70%心率范围（HRR）进行自行车运动时，测量大脑中动脉血流速度（MCAv；多普勒）和皮质血液动力学（NIRS）。使用计算机适应的 Stroop 任务（即执行功能认知测试）在休息和运动时评估认知表现。对于简单和困难任务，老年人的平均反应时间均慢于年轻人（P<0.01）。与年龄无关，在运动过程中，困难任务的反应时间会改善（P<0.01），在 70%HRR 运动时改善更大（P=0.04 比 30%HRR）。MCAv 越高，在休息时简单和困难任务的反应时间就越快（R(2)=0.47 和 R(2)=0.47），但在运动过程中，这种关系逐渐失去耦合。对于两个年龄组，MCAv 的运动诱导增加在认知任务期间是相似且不变的。相比之下，前额皮质血液动力学 NIRS 测量值[氧合血红蛋白（O(2)Hb）和总血红蛋白（tHb）]受到运动强度、年龄和认知任务的不同影响；例如，在运动强度之间，老年组的[O(2)Hb]和[tHb]增加较小（P<0.05）。这些数据表明：1）无论年龄大小，运动时认知（执行）功能都会提高；2）虽然 MCAv 在休息时与认知密切相关，但这种关系在运动时会失去耦合，3）在运动和参与前额叶认知时，全局 CBF 与局部皮质氧合和 NIRS 血液量标记之间存在分离。
