Aging isn’t only a downhill journey. While some of our mental faculties almost always decline over time, other cognitive abilities can stay the same, or even improve, scientists have discovered. The overall balance of these losses and gains means that for most people, the ideal time to tackle leadership roles is in their mid-50s, according to Darlene Howard, a psychologist emerita at Georgetown University.

In healthy individuals, some parts of the brain shrink starting in our 20s. This shrinkage, which is not a loss of neurons but rather changes in size and connections among neurons, leads to differences in cognitive functions. In most cases, these changes are so gradual, it’s easy to adapt to them over time. On average, older adults tend to lose capabilities like mental speed, which can affect reaction times or the ability to connect different types of information, compared to younger individuals. Learning new material can become more difficult (but not impossible), and it may become harder to recall specific words or remain focused on a specific task in the presence of distractions. The brain has some flexibility, though. In 2009, Denise Park, a psychologist at the University of Texas at Dallas, and Patricia Reuter-Lorenz at the University of Michigan gave this flexibility a name: STAC, or the Scaffolding Theory of Aging and Cognition. The theory states that as the brain perceives challenges to cognition, it can find new ways to work around them. An older person may use more regions of their brain to accomplish a task than a younger individual, but both people could do the job equally well.

In some cases this adaptation may actually be beneficial. Older adults can have better vocabularies, because, although recalling words may be harder, they’ve had time to learn more of them, Howard said. They can also be better at solving interpersonal or abstract problems. Temporal discounting, or valuing the future just as much if not more than the present, tends to also get better with age, as does the ability to regulate emotions and cope with negative feelings, Howard explained at a forum at the National Press Foundation earlier this month.

At what point are the cognitive gains associated with aging at their maximum, while losses are at a minimum? Probably mid-50s, Howard said, when asked about the ideal age for a U.S. president. However, there’s so much variability in the way that individual’s brains may change over time, it’s not a perfect predictor of ideal leadership skills.

Words to Learn 相关词汇

【荣誉退休的】róngyù tuìxiū de emerita retired or honorably discharged from active professional duty, but retaining the title of one’s office or position

【认知的】rènzhī de cognitive of, relating to, being, or involving conscious intellectual activity

变老不意味着什么都在走下坡路。科学家发现，尽管我们的一部分大脑功能随着年龄增长而衰退，其他认知能力则会保持不变甚至会变强。乔治城大学的心理学家荣誉退休教授达琳●霍华德指出，综合平衡这些得失的结果显示，多数人的领导能力在55岁左右达到高峰。

健康人的大脑会从20多岁开始部分萎缩。这种萎缩不是丧失神经元，而是神经元的大小和联系发生改变，导致认知能力的差异。在大多数情况下，这些改变都是逐渐发生的，随着时间流逝人们可以轻松适应这些改变。平均而言，年长的成年人和年轻人相比，大脑反应速度会变慢，将不同类型信息联系到一起的能力也会减退。学习新知识会变得更困难（但也不是不可能），而且更难以回忆起特定词汇，或在受干扰的情况下集中注意力处理特定任务。

不过，大脑也会灵活应对这些改变。2009年，美国达拉斯市的德克萨斯大学的心理学家丹尼斯●帕克和密歇根大学的帕特丽夏●路透●洛伦兹给这种灵活性起了一个名字：变老与认知的脚手架理论（缩写为STAC）。这一理论指出，大脑会察觉到认知的挑战，因此会找到绕过挑战的新工作方式。年纪更大的人在执行任务时可能会比年轻人运用更多的大脑区域，但两者能同样出色地完成工作。

在某些情况下，大脑的这种应变实际上可能是有益的。霍华德说，年长的人词汇量更大，尽管更难以回忆起词汇，但他们过去所学的词汇更多。而且，他们更善于解决人际问题或抽象问题。霍华德在本月初的国家新闻基金会的一个论坛上解释说，随着年龄增长，时间贴现或更重视未来回报的能力也会提高，与此同时，调节情绪和应对负面情绪的能力也会改善。

那么，伴随年龄而来的认知红利最大化而认知能力衰退最小化的平衡点是几岁呢？很可能是55岁，被问及美国总统最理想年龄时霍华德回答道。但是，个体的大脑随着时间会发生各种改变，所以不能用55岁来界定最佳领导力。(Chinadaily.com.cn)