Stress in middle age can make your brain shrink and make your memory worse, scientists have discovered.

科学家发现，中年压力会让人的大脑萎缩和记忆力变差。

The brain-reducing effects of stress, identified in people in their 40s free from dementia, were found to be triggered by cortisol.

压力令大脑萎缩这一影响是由皮质醇引发的。科学家在没有罹患痴呆症的40多岁人群中发现了这一影响。

The high levels of the stress hormone¹ may be an early warning sign someone may end up with dementia, the research suggests.

研究结果表明，压力荷尔蒙的高含量可能是一个早期预警信号，表明某人可能会患上痴呆症。

Stress also made people’s thinking skills worse, the Harvard Medical School study, published in the journal Neurology, found.

哈佛大学医学院的这项研究结果发现，压力还造成人们的思维技能变差。这项结果发表在美国《神经学》周刊上。

For the research, scientists led by Dr Justin Echouffo-Tcheugui studied 2,231 people with an average age of 49 and free of dementia.

在这项研究中，以贾斯廷·埃舒福-楚吉博士为首的科学家对2231名平均年龄为49岁、没有痴呆症的人进行了研究。

He said: ’Our research detected memory loss and brain shrinkage in middle-aged² people before symptoms started to show.

埃舒福-楚吉说：“我们的研究结果发现，在症状开始显现前，中年人出现了记忆力丧失和脑萎缩的情况。”

So it’s important for people to find ways to reduce stress, such as getting enough sleep, engaging in moderate exercise, incorporating relaxation³ techniques into their daily lives, or asking their doctor about their cortisol levels and taking a cortisol-reducing medication if needed.’

他说：“因此，人们找到减轻压力的方法很重要，比如获得充分睡眠，适度锻炼，把放松技术融入日常生活，或者向医生询问自己的皮质醇水平，如有必要，服用降低皮质醇水平的药物。”

He added: ’It’s important for physicians to counsel all people with higher cortisol levels.’

他还说：“重要的是，医生要向所有皮质醇水平较高的人提供咨询。”

At the start of the study, each participant did tests on their memory and thinking skills. Then eight years later they repeated the exercises.

在研究开始时，每位参与者都接受了记忆和思维能力的测试。8年后，他们再次接受了测试。

A subset of the group, 2,018 people, also had an MRI brain scan to measure the volume of their brain.

这群人中的2018人还接受了脑核磁共振扫描，以测量他们的脑容量。

Once the results were adjusted for age, sex, smoking and body mass, researchers found lower scores on tests of memory and thinking in people with higher levels of cortisol than those with average levels.

研究人员在根据年龄、性别、吸烟情况和体重进行调整后发现，皮质醇水平较高的人在记忆力和思维能力测试中的分数低于皮质醇处于平均水平的人。

In addition, people with higher cortisol levels had a smaller brain volume, with those with high cortisol having brains that were 88.5 per cent of the total cranial volume.

此外，皮质醇水平较高的人脑容量较小，其脑容量占颅容量的88.5%。

This was compared to 88.7 per cent of total cranial volume for people with normal levels of the hormone.

相比之下，皮质醇水平正常的人，其脑容量占颅容量的88.7%。

No links were found between low levels of cortisol and brain size.

研究人员没有发现皮质醇水平低与脑容量之间存在关联。

Cortisol, produced by the adrenal glands⁴, helps the body respond to stress.

肾上腺分泌的皮质醇能帮助身体应对压力。

It can also help reduce inflammation, control blood sugar and blood pressure, regulate metabolism⁵ and help with immune response.

它还能帮助减轻炎症、控制血糖和血压、调节新陈代谢以及帮助应对免疫反应。

High cortisol levels can be caused by stress, medical conditions or medications.

皮质醇水平高可能是由压力、疾病或药物造成的。

Dr Echouffo-Tcheugui said: ’Cortisol affects many different functions so it is important to fully investigate how high levels of the hormone may affect the brain.’

埃舒福-楚吉博士说：“皮质醇会影响很多不同的功能，因此全面研究皮质醇水平高对大脑的可能影响非常重要。”