A gradual breakdown of communication between different parts of the brain helps to explain why mental functions decline in old age, even in people who do not suffer from a disease such as Alzheimer's.

Researchers at Harvard University used magnetic resonance imaging to monitor the “crosstalk” that passes through the white matter connecting different regions of the brain. Their findings are published in the journal Neuron.

The scientists studied 93 people aged from 18 to 93 as they undertook a battery of tests to measure their cognitive abilities. They found much less crosstalk in the brains of older subjects and the different regions of the brain became increasingly “out of sync” with increasing age. Subjects with more communication between brain regions tended to do better in the cognitive tests.

Jessica Andrews-Hanna, the study leader, said that, although some deterioration in intra-brain communication was a normal consequence of ageing, there were some exceptions. “It may explain why some people are just as sharp in their 90s as they are in their 40s,” she said. “We all age differently.”

随年龄增长，大脑各部分之间的沟通联系逐渐减少。这一发现有助于解释为什么老年人即便没有患上阿尔茨海默病(Alzheimer's, 即老年性痴呆)，各项智力功能也会有所衰退。

哈佛大学(Harvard University)的研究人员使用磁共振成像技术，来监控通过脑白质的“相互交流”。这些脑白质联系着大脑的不同部分。他们的研究成果发表在专业杂志《神经元》(Neuron)上。

这些科学家对93位年龄在18到93岁的研究对象进行了成套测验，以测量他们的认知能力。他们发现，较为年长者大脑中的相互交流较少，而且随着年龄的增加，大脑的不同部分变得越来越“不协调”。在大脑不同区域之间有着更多交流的对象，往往在认知力测试中表现得更好。

研究负责人杰西卡•安德鲁斯•哈纳(Jessica Andrews-Hanna)表示，虽然大脑内部交流通常随着年龄增长出现衰退，但也有一些例外。“这可能会揭示为什么有些人在90多岁时还像40多岁时一样思维敏捷，”她表示。“我们都会以不同的方式变老。”

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