Abstract：
Prior studies have identified variable effects of healthy aging on neurovascular coupling (NVC). Carbon dioxide (CO2) affects both cerebral blood velocity (CBv) and NVC, but the effects of age on NVC under different CO2 conditions are unknown. Therefore, we investigated the effects of aging on NVC in different CO2 states in healthy controls during cognitive paradigms. 78 healthy participants (18-78 years) underwent continuous recordings of CBv by bilateral insonation of middle (MCA) and posterior (PCA) cerebral arteries (transcranial Doppler), blood pressure, end-tidal CO2, and heart rate during poikilocapnia, hypercapnia (5% CO2 inhalation) and hypocapnia (paced hyperventilation). Neuroactivation via visuospatial (VS) and attention tasks (AT) augmented CBv. Peak percentage change in MCAv/PCAv, were compared between CO2 conditions and age groups (< 30, 31-60, and >60 years). For the VS task, in normocapnia, younger adults had a lower NVC response compared to older adults (mean difference (MD): -7.92% (standard deviation (SD): 2.37), p=0.004), but comparable between younger and middle-aged groups. In hypercapnia, both younger (MD: -4.75% (SD: 1.56), p=0.009) and middle (MD: -4.58% (SD: 1.69), p=0.023) age groups had lower NVC responses compared to older adults. Finally, in hypocapnia, both older (MD: 5.92% (SD: 2.21), p=0.025) and middle (MD: 5.44% (SD: 2.27), p=0.049) age groups had greater NVC responses, compared to younger adults. In conclusion, the middle-aged adults demonstrated a variable NVC response, comparable to younger adults under hypercapnia, and older adults under hypocapnia. This may owe to a more cognitively favourable profile while under hypercapnic conditions, compared to hypocapnia.
摘要：
先前的研究已经确定了健康衰老对神经血管偶联（NVC）的可变影响。二氧化碳（CO2）影响脑血流速度（CBv）和NVC，但不同CO2条件下年龄对NVC的影响尚不清楚。因此,我们调查了认知范式中健康对照者不同CO2状态下衰老对NVC的影响.78名健康参与者（18-78岁）通过双侧中（MCA）和后（PCA）脑动脉（经颅多普勒）的超声连续记录CBv，血压,潮气末二氧化碳和poikilocapnia期间的心率，高碳酸血症（5％CO2吸入）和低碳酸血症（节奏过度换气）。通过视觉空间（VS）和注意力任务（AT）增强CBv的神经激活。MCAv/PCAv的峰值百分比变化，在CO2条件和年龄组(<30、31-60和>60岁)之间进行比较。对于VS任务，在正常碳酸血症中，与老年人相比，年轻人的NVC反应较低（平均差异（MD）：-7.92％（标准偏差（SD）：2.37），p=0.004),但在年轻和中年群体之间相当。在高碳酸血症中，均较年轻（MD：-4.75%（SD：1.56），p=0.009)和中等(MD:-4.58%(SD:1.69)，p=0.023）年龄组的NVC反应低于老年人。最后,在低碳酸血症中，两者都较老(MD:5.92%(SD:2.21)，p=0.025)和中间(MD:5.44%(SD:2.27)，p=0.049)年龄组有更大的NVC反应，与年轻人相比。总之,中年人表现出可变的NVC反应，与高碳酸血症下的年轻成年人相当，和老年人低碳酸血症。这可能归因于在高碳酸血症条件下更有利的认知特征，与低碳酸血症相比。
