人到四十 全職工作竟然會影響大腦?

Don't do an IQ test after a full week's work if you are 40 years or older. You could be disappointed.

如果你已經40歲了或者更大，那麼工作一整週之後不要做智商測試，因爲結果可能會令你大失所望。

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.

根據澳大利亞墨爾本應用經濟和社會研究所於二月份發表的一項研究表明，如果你已年過40，每週工作超過25個小時可能會損害你的智力。

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.

該研究團隊對6000餘名40歲以上的上班族進行了閱讀、記憶力測試，企圖搞清楚每週的工作時間是如何影響人的認知能力的。

"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."

東京慶應大學的經濟學教授、主要研究員科林·麥肯齊表示："工作能夠刺激大腦活動並幫助老年工作者維持認知功能。但與此同時，過長的工作時間會造成疲勞，帶來身體（和/或）心理壓力，這就會潛在地損害了認知功能。"

But why is age 40 the turning point for the mind?

但爲何40歲是大腦的轉折點呢？

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.

根據麥肯齊教授的說法，我們的"可變智力"，即處理信息的水平，在20歲左右就開始衰退。而"固化智力"，即與技巧、知識和經驗有關的能力，在30歲後便開始衰退。麥肯齊教授表示，到40歲的時候，大部分人的記憶測試、圖像認知以及大腦靈活性都表現的更差。

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.

麥肯齊教授的研究表明，雖然當前經濟發展可能會迫使我們比前幾代人工作更長時間，但從生物學和情感上來說，當我們年過40，我們的大腦可能就不適應朝九晚五、每週五天的的壓力和重複的工作了。