英语听力文摘《记忆与糖》

以前常听说心情与糖的关系，据说甜味会让人快乐。那么，记忆与糖呢?这二者可存在什么关系?

　　Memory and Sugar

　Sugar On The Brain

It’s long been understood that there is a connection between memory problems and diabetes, a disorder characterized by excessively high blood sugar. Sugar provides the body with fuel for various processes, including memory processing. In fact, glucose carried in the blood stream supplies the brain with 90 percent of the energy it requires to function properly.

In order to fuel those processes glucose has to get from the blood to the tissues, where it can be broken down and put to work. High blood sugar levels, such as in diabetes, are an indicator that a body is experiencing difficulty moving sugar from the blood to the tissues.

However, some non-diabetics have a less severe form of high blood sugar, a condition called impaired glucose tolerance. And it is this condition that seems to be the cause of memory problems in a significant number of non-diabetic elderly people who experience memory difficulties.

　Sweet Nothings

Subjects were given glucose intravenously, and then researchers measured how quickly glucose moved from the blood to the tissues. Next the subjects were tested for overall cognitive functioning and the ability to recall short paragraphs. The results? Subjects who scored lowest on memory recall tests also showed impaired glucose tolerance.

In addition, brain scans demonstrated that these same subjects each had a significantly smaller hippocampus, a brain area important to learning and memory. The researchers hypothesize that impaired glucose tolerance may over time cause damage and atrophy to the hippocampus.

What can a body do to prevent this? A healthy diet and exercise can help maintain good glucose tolerance, perhaps preventing gradual memory decline.

记忆与糖

　大脑中的糖

健忘与糖尿病有关，这个人们早就知道。糖尿病是一种以血液中含糖量过高为特征的`疾病。糖为身体的各项功能提供能量，其中就包括记忆功能。事实上，血液中的葡萄糖为脑部功能正常运作提供了90%的能量。

为了给这些功能提供能量，葡萄糖必需从血液进入到身体组织中，在那里葡萄糖得到分解并发挥效用。血液中含糖量太高，比如糖尿病就是这样，表明身体在将糖从血液运输到身体组织时发生困难。

然而，一些非糖尿病患者，他们体内含糖量高的病症较轻微，这种病叫做葡萄糖耐受性受损。而广大记忆产生障碍的老年非糖尿病患者会发生记忆衰退就是由该病导致。

　"无用武之地"的糖

研究人员向实验对象进行静脉注射，然后测量葡萄糖从血液运输到身体组织中有多快。接下来，研究人员测验实验对象总体认知功能及记忆短句的能力。结果如何?在记忆环节得分最低的实验对象，同时也表现出葡萄糖耐受性受损的症状。

此外，大脑扫描表明患有该病的此类实验对象，大脑中对学习记忆非常重要的部位──海马体，很明显体积较小。研究人员猜测葡萄糖耐受性衰退可能长期对海马体造成伤害使其萎缩。

那么我们该如何预防此类疾病呢?健康的饮食和进行锻炼有助于保持良好的葡萄糖耐受性，这也许可以防止记忆衰退。