中年人过胖，大脑年龄恐老化10岁

肥胖的中年人脑内白质明显减少

　　2016年8月4日，英国剑桥大学和美国耶鲁大学发表在《老化神经生物学》的研究指出，中年过胖的人大脑内的白质会减少，和正常体重的中年人相比，肥胖的中年人脑内白质组织明显减少。白质控制神经元共享的信号，协调大脑间的运作。

　　负责这项研究的剑桥大学科学家说：随年龄增长，我们的脑容量会逐步减少，胖人的相应进程会比体重正常的人快，我们不知道个中原因，只能猜想是不是肥胖会加速大脑萎缩。

　　随着白质的减少，一位年约40岁过胖的中年人，大脑年龄约老10岁。而这10岁的差距还会一直保持下去，实际年龄50岁时大脑年龄已60岁。

　　该研究对527位年龄20～87岁剑桥居民的脑部影像进行研究，发现人脑内白质大幅减少仅出现在中年人身上。

　　不过，研究还发现过重或纤瘦的受试者，其智力以及认知能力无显著差异。

　　科学家表示随着年纪增长，大脑自然会缩小，但肥胖或过重的人显示出白质明显减少，让科学家怀疑身体肥胖是否会导致大脑变异，或是因白质减少导致身体过重，两者间的因果关系还有待进一步研究。

　　解答这个问题非常重要，因为地球上的居民正迅速地变老变胖，防止大脑衰老或成为未来数十年的主要医学任务。

Neurobiol Aging. 2016 Jul 27. [Epub ahead of print]

Obesity associated with increased brain-age from mid-life.

Lisa Ronan, Aaron F. Alexander-Bloch, Konrad Wagstyl, Sadaf Farooqi, Carol Brayne, Lorraine K. Tyler, Cam-CAN, Paul C. Fletcher.

Brain Mapping Unit, Department of Psychiatry, University of Cambridge, UK; Yale School of Medicine, Yale University, USA; Institute of Metabolic Sciences, Department of Clinical Biochemistry, Cambridge, UK; Institute of Public Health, University of Cambridge, Cambridge, UK; Cambridge Center for Ageing and Neuroscience (Cam-CAN) and MRC Cognition and Brain Sciences Unit, Cambridge, UK.

Common mechanisms in aging and obesity are hypothesized to increase susceptibility to neurodegeneration, however direct evidence in support of this hypothesis is lacking. We therefore performed a cross-sectional analysis of MRI-based brain structure on a population-based cohort of healthy adults. Study participants were originally part of the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) and included 527 individuals aged 20 - 87 years. Cortical reconstruction techniques were used to generate measures of whole brain cerebral white matter volume, cortical thickness and surface area. Results indicated that cerebral white matter volume in overweight and obese individuals was associated with a greater degree of atrophy, with maximal effects in middle-age corresponding to an estimated increase of brain-age of 10 years. There were no similar BMI-related changes in cortical parameters. This study suggests that at a population level, obesity may increase the risk of neurodegeneration.

Keywords: obesity; white matter volume; structural MRI; population-based

DOI: 10.1016/j.neurobiolaging.2016.07.010