Don't do an IQ test after a full week's work if you are 40 years or older. You could be disappointed.
如果你已经40岁了或者更大，那么工作一整周之后不要做智商测试，因为结果可能会令你大失所望。
If you're over 40, working more than 25 hours of work a week could be impairing your intelligence, according to a study released in February by researchers for the Melbourne Institute of Applied Economic and Social Research in Australia.
根据澳大利亚墨尔本应用经济和社会研究所于二月份发表的一项研究表明，如果你已年过40，每周工作超过25个小时可能会损害你的智力。
The team conducted reading and memory tests in more than 6,000 workers aged over 40, to see how the number of hours worked each week affects a person's cognitive ability.
该研究团队对6000余名40岁以上的上班族进行了阅读、记忆力测试，企图搞清楚每周的工作时间是如何影响人的认知能力的。

"Work can stimulate brain activity and can help maintain cognitive functions for elderly workers." said lead researcher Colin McKenzie, a professor of economics at Keio University in Tokyo. "But at the same time, excessively long working hours can cause fatigue and physical and/or psychological stress, which potentially damage cognitive functioning."
东京庆应大学的经济学教授、主要研究员科林·麦肯齐表示："工作能够刺激大脑活动并帮助老年工作者维持认知功能。但与此同时，过长的工作时间会造成疲劳，带来身体（和/或）心理压力，这就会潜在地损害了认知功能。"
But why is age 40 the turning point for the mind?
但为何40岁是大脑的转折点呢？
According to McKenzie, our "fluid intelligence", which is how well we process information, starts declining around the age of 20 and "crystallised intelligence", or the ability to use skills, knowledge and experience starts decreasing after 30 years of age. McKenzie said that by age 40, most people perform less well at memory tests, pattern recognition and mental agility exercises.
根据麦肯齐教授的说法，我们的"可变智力"，即处理信息的水平，在20岁左右就开始衰退。而"固化智力"，即与技巧、知识和经验有关的能力，在30岁后便开始衰退。麦肯齐教授表示，到40岁的时候，大部分人的记忆测试、图像认知以及大脑灵活性都表现的更差。
McKenzie's findings suggest that although economics may now be forcing us to work much longer than in previous generations, biologically and emotionally our minds may not be designed for the stress and repetition of working nine-to-five, five days a week when we are over 40.
麦肯齐教授的研究表明，虽然当前经济发展可能会迫使我们比前几代人工作更长时间，但从生物学和情感上来说，当我们年过40，我们的大脑可能就不适应朝九晚五、每周五天的的压力和重复的工作了。