Centre for Human Psychopharmacology, Swinburne University, Hawthorn Victoria, Australia.
Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia.
PLoS One. 2018 May 22;13(5):e0197055. doi: 10.1371/journal.pone.0197055. eCollection 2018.
Understanding how vascular and metabolic factors impact on cognitive function is essential to develop efficient therapies to prevent and treat cognitive losses in older age. Cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and venous oxygenation (Yv) comprise key physiologic processes that maintain optimum functioning of neural activity. Changes to these parameters across the lifespan may precede neurodegeneration and contribute to age-related cognitive decline. This study examined differences in blood flow and metabolism between 31 healthy younger (<50 years) and 29 healthy older (>50 years) adults; and investigated whether these parameters contribute to cognitive performance.
Participants underwent a cognitive assessment and MRI scan. Grey matter CMRO2 was calculated from measures of CBF (phase contrast MRI), arterial and venous oxygenation (TRUST MRI) to assess group differences in physiological function and the contribution of these parameters to cognition.
Performance on memory (p<0.001) and attention tasks (p<0.001) and total CBF were reduced (p<0.05), and Yv trended toward a decrease (p = .06) in the older group, while grey matter CBF and CMRO2 did not differ between the age groups. Attention was negatively associated with CBF when adjusted (p<0.05) in the older adults, but not in the younger group. There was no such relationship with memory. Neither cognitive measure was associated with oxygen metabolism or venous oxygenation in either age group.
Findings indicated an age-related imbalance between oxygen delivery, consumption and demand, evidenced by a decreased supply of oxygen with unchanged metabolism resulting in increased oxygen extraction. CBF predicted attention when the age-effect was controlled, suggesting a task- specific CBF- cognition relationship.
了解血管和代谢因素如何影响认知功能对于开发有效的治疗方法来预防和治疗老年认知损失至关重要。脑氧代谢率（CMRO2）、脑血流量（CBF）和静脉氧合（Yv）构成了维持神经活动最佳功能的关键生理过程。这些参数在整个生命周期中的变化可能先于神经退行性变并导致与年龄相关的认知下降。本研究检查了 31 名健康年轻（<50 岁）和 29 名健康年长（>50 岁）成年人之间的血流和代谢差异；并调查了这些参数是否对认知表现有贡献。
参与者接受了认知评估和 MRI 扫描。从 CBF（相衬 MRI）、动脉和静脉氧合（TRUST MRI）的测量中计算灰质 CMRO2，以评估生理功能的组间差异以及这些参数对认知的贡献。
记忆（p<0.001）和注意力任务（p<0.001）的表现以及总 CBF 降低（p<0.05），Yv 呈下降趋势（p =.06），而灰质 CBF 和 CMRO2 在年龄组之间没有差异。注意力与 CBF 呈负相关，当在老年人中进行调整（p<0.05）时，但在年轻组中则没有。在任何年龄组中，记忆与氧代谢或静脉氧合均无关联。
研究结果表明，与氧气输送、消耗和需求之间存在与年龄相关的不平衡，这表现为氧气供应减少而代谢不变导致氧气提取增加。当控制年龄效应时，CBF 预测了注意力，这表明存在特定于任务的 CBF-认知关系。
