身心锻炼想象改善高龄老人执行功能的脑成像追踪研究

The oldest old is the most rapidly growing age group in China. Aging is associated with deterioration in brain anatomical structures and cognitive functions, which affects life expectancy and well-being of the oldest old. Despite the inevitable age-related decline, the aging brain maintains its plasticity, which is the capacity to modify the structure or function of the nervous system in response to environmental stimulation, impairment, or dysfunction. Improving cognitive function in the oldest old has become an attractive research topic in psychology in recent years. Earlier research suggests that physical exercise, such as strength training and aerobic exercise, can prevent cognitive dysfunction and promote executive function in healthy adults. However, such physical training is intimidating and unsafe for many oldest-old individuals. For this reason, it is imperative to identify/develop a training regimen that is suitable for frail older people to improve their executive function. Accumulating evidence in recent years has shown that motor imagery training (MIT) without overt body movement can also accelerate learning and improve memory. Human brain imaging using hemodynamic markers (PET and fMRI) and extracerebral magnetic and electric field studies (MEG and EEG) have shown that motor imagery activates many of the same neocortical areas as those involved in planning and execution of motor movements (e.g., medial supplemental motor area, premotor cortex, dorsolateral prefrontal cortex, and posterior parietal cortex). Furthermore, older adults aged 60 years and over benefited more from MIT than did adults ranging from 21 to 59 years old. Although the effect of MIT on memory and learning is recognized in healthy young populations, little is known regarding its application to improving executive function in frail oldest-old individuals and its underlying physiological mechanisms. Preliminary data from our laboratory show that older adults who underwent 8 weeks of Baduanjin mind-body (BMB) exercise can significantly improve their response inhibition, which is one of the core executive functions (EFs). These above-mentioned findings lead to our hypothesis that there are positive effects of BMB motor imagery on the executive functions, i.e. inhibition, updating and shifting. Executive function improvement depends primarily on the level of brain effective connectivity during motor-imagery and execution, not the exercise intensity per se. We will test this fundamental hypothesis in the oldest-old population firstly by investigating the effects of BMB motor imagery on inhibition, updating and shifting function using both behavioral and near-infrared spectroscopy (NIRS) approaches, and then by establishing the magnitude and time course of BMB motor imagery-associated changes in the fMRI-based brain connectivity. In particular, we determine how the optimal proportions of real execution and motor imagery can lead to similar (or even better) performance of executive function rather than physical practice alone. These findings may be important and useful to make a safe and potentially effective training protocol for preserving execution function with aging-related cognitive decline.

高龄老人是老年人口中的脆弱群体，其执行功能衰退更为严重，但是大脑可塑性依然存在。常规的锻炼方法因其安全隐患不适合高龄老人参加，需要寻找替代性方法。八段锦作为一种身心锻炼方法，其动作简单易学，适合高龄老人想象训练。课题组前期研究显示，八段锦锻炼对执行功能有积极影响；另有研究表明，运动想象训练也可增强老年人的执行功能，因此我们假设：八段锦锻炼想象能够改善高龄老人的执行功能。本项目首先从行为层面和神经活动层面，考察八段锦身心锻炼想象对高龄老人执行功能3个子成份的影响。在此基础上，比较不同干预模式对于改善高龄老人执行功能效果。然后追踪身心锻炼想象干预效果的时间累积效应及其与高龄老人脑区连接模式的关联；最后进一步分析身心锻炼想象干预停止后，其认知效益的消退进程。研究结果将有助于理解身心锻炼想象训练改善高龄老年人执行功能的脑神经机制，同时为设计适合高龄老年人参加的认知训练方法提供启示。

当前，我国人口老龄化现象已成为困扰全社会的重要问题。高龄老人是老年人口中的脆弱群体，其执行功能衰退更为严重，但是大脑可塑性依然存在。常规的锻炼方法因其安全隐患不适合高龄老人参加，需要寻找替代性方法。八段锦作为一种身心锻炼方法，其动作简单易学，适合高龄老人想象训练。已有研究显示，八段锦锻炼对执行功能有积极影响；另有研究表明，运动想象训练也可增强老年人的执行功能，因此我们假设：身心锻炼想象能够改善高龄老人的执行功能。. 本项目首先从行为层面和神经活动层面，考察身心锻炼想象对高龄老人执行功能不同成份的影响。研究发现,身心锻炼想象有助于增强被试的抑制控制能力、改善其工作记忆，提高大脑相关脑区的激活。在此基础上，研究者比较了不同干预模式对于改善高龄老人执行功能效果。发现想象的身心锻炼和实际执行的身心锻炼均有助于改善被试的执行功能，而且两者有着类似的神经活动模式。此外，研究还进一步发现，较之于一次性的干预，长期运动干预对老年人的认知和脑功能的改善效果的优于一次性的干预效果。研究结果将有助于理解身心锻炼想象训练改善高龄老年人执行功能的脑神经机制，同时为设计适合高龄老年人参加的认知训练方法提供启示。