保持大脑活力：30岁后延缓认知衰退的科学策略
Big Think
2026-04-30
身体与大脑的互动：认知衰退的生理基础与应对之道
你身体的活动会影响你的大脑，而你大脑的思考方式同样会作用于你身体的生理机能。这种联系是双向的。自古以来，人们就认识到经验能够改变大脑，尤其是在大脑被确认为意识、思想和体验的载体之后。为了生长和保持可塑性，大脑必须发生变化。
随着年龄增长，记忆力往往会下降，因为我们的大脑，就像身体的其他部分一样，会逐渐衰老，其功能不再像年轻时那样持续。为了让大脑在年长时保持健康和良好运作，你可以采取的一种方法是保持一种精神上积极投入的生活方式。
每一次你活动身体，你都在为大脑提供我称之为“神经化学物质的美妙泡沫浴”。这些神经化学物质（Neurochemicals: 身体内用于神经信号传递的化学物质，如多巴胺、血清素等）包括多巴胺（Dopamine: 调节情绪、动机和奖励的神经递质）、血清素（Serotonin: 影响情绪、睡眠和食欲的神经递质）、去甲肾上腺素（Noradrenaline: 参与警觉性和反应的神经递质）和内啡肽（Endorphins: 产生愉悦感和减轻疼痛的神经递质）。
好消息是，你无需成为马拉松选手也能获得这些益处，因为即使是十分钟的步行也能立即带来缓解焦虑和抑郁水平的好处。运动带来的长寿效应，是当下每个人都需要关注的。
随着衰老，会出现不同类型的认知和记忆丧失。某些类型的记忆丧失，例如忘记车钥匙放在哪里，是衰老过程的正常部分。事实上，记忆力在30岁左右达到顶峰，然后随着时间逐渐衰退。如果你忘记了眼镜放在哪里，那是正常的记忆丧失。但如果你忘记了你戴眼镜这件事，那就是痴呆症了。
目前尚不完全清楚这背后的具体生理机制。但一些有力的候选解释包括大脑形成新连接的能力减弱，或者神经细胞之间连接权重的调节能力下降，这些连接权重被称为突触权重（Synaptic Weights: 神经元之间连接的强度）。这些因素可能解释了为什么随着年龄增长，大脑在某些方面似乎变得不那么具有可塑性。
通过检查已故且被诊断患有阿尔茨海默病的人的大脑，我们可以看到斑块（Plaques: 蛋白质异常聚集物）和缠结（Tangles: 神经纤维缠绕的异常结构）的存在，它们似乎是细胞死亡的原因，或者是细胞死亡后的残余物。
为了保持大脑的活力和健康，你可以做的最重要的事情之一就是改善流向大脑的血流量（Blood Flow: 血液在血管中循环输送氧气和营养的过程）。
另一个被提出的主要机制是分泌一种名为脑源性神经营养因子（Brain-Derived Neurotrophic Factor, BDNF: 一种促进神经元生长、存活和可塑性的蛋白质）的信号分子。这种在脑内产生的因子能够促进神经元的生长，并已被证明能改善树突（Dendrites: 神经元的接收信号部分）的可塑性。
因此，运动通过触发BDNF的分泌，可能导致大脑可塑性的增强和脑功能的改善。当我们面临挑战时，我们能做得更多，这一点人尽皆知。而在没有挑战的情况下，我们可能无法充分发挥潜力。当前的目标是设法将这些认知衰退推迟几年，因为随着我们寿命的延长，这几年变得尤为重要。
最大的问题并非出在长期记忆上，而是短期记忆。我们可以清晰地记得高中时的初吻，却可能记不起午餐吃了什么。由于大脑的萎缩，脑细胞的效率开始降低并随着时间死亡。脑细胞之间的连接减少，神经化学递质似乎也出现问题。所有这些生理变化都会导致我们随着年龄增长而出现记忆问题。
记忆基本上是以大脑中的微小神经化学信号包的形式存储的。因此，它们可以被改变，而我们的记忆也可能经常欺骗我们。
然而，通过相对简单的策略和技巧，提高我们的记忆能力是完全可能的。我经常建议人们寻找自己个人偏好的事物。这些事物应该是对精神有挑战性但又不过于困难的。关键在于训练而非过度劳累大脑。无论是填字游戏、学习语言，还是演奏乐器，尝试不同的事物并找到适合自己且令人愉悦的方式至关重要。
之所以每个人都有希望，是因为大脑可塑性（Brain Plasticity: 大脑根据环境和经验改变其结构和功能的能力）这一原理。大脑可塑性意味着大脑拥有非凡的能力，能够根据你所处的环境（包括物理环境）来改变或调整其连接方式。你是否经常散步？你是否跑步？你是否保持身体活跃？这些都会带来我所说的积极大脑可塑性。
一个久坐不动的大脑与跑步者的大脑有何不同？跑步者的大脑在每次跑步后，多巴胺和血清素水平都会升高，从而提升整体情绪状态。我在实验室进行的研究表明，坚持三个月动感单车课程的人，其整体情绪状态要高于三个月内玩视频填字游戏的人。运动组的人大脑中流动的生长因子也更多。我喜欢将其比作一个装满生长因子的喷壶，遍布海马体。正在发生的是：它们在生长，生成崭新的海马体细胞，并使前额叶皮层功能更好。
但再次强调，一切都随着大脑可塑性而流动。即使你一生都久坐不动，只需十分钟的步行，你就可以开始朝着我所说的“更大、更强壮、更饱满、更快乐的大脑”迈进。我们发现了同样的益处：更好的情绪、降低的焦虑和抑郁水平，以及更好的专注力。
身体活动是你能够为你的身体乃至大脑所做的最具变革性的事情。
以下是该逻辑块对应的英文原文归档：
Original English
[TRANSCRIPT_START]
What you do with your body affects your brain.
And what you think with your brain
also has an effect
on the physiology of your body.
It works both ways.
People have known that experience
can change the brain
ever since it became known that the brain
was the seat of consciousness,
thought and experience.
The brain must undergo change
to grow and to be plastic.
Memory tends to decrease with age
because our brains,
like the rest of our body
tends to age and
function does not continue
the way it does when we're young.
One of the things that you can do to
keep your brain happy
and functioning well as you get older
is to have a mentally engaged lifestyle.
Every single time you move your body
you are giving your brain
what I like to call a wonderful bubble
bath of neurochemicals.
Those neurochemicals include dopamine
serotonin
noradrenaline
endorphins.
Here's the good news: You don't have to
be a marathon runner to get this,
because even ten minutes of walking
will start to give you immediate
benefits in terms of decreasing anxiety
levels, decreasing depression levels.
The longevity that comes with exercise,
that's what everybody needs right now.
So there’s different kinds of cognitive
and memory loss that occur with aging.
Certain kinds of memory loss, such
as forgetting where your car keys are
are part of the normal process
of getting older.
And in fact, memory peaks surprisingly early at the age of 30
and then declines gradually with time.
If you forget where your glasses are,
that's normal memory loss.
If you forget the fact that you wear
glasses, that's dementia.
It's not well understood
exactly what physically underlies this.
Although plausible candidates
are loss of the brain's ability
to form new connections
or to easily modulate the weight
of the connections between nerve cells,
those are called synaptic weights.
And so those would be candidates
for why the brain seems to be less plastic
in certain ways as we get older.
You can look in the brains of people
who, after death, are diagnosed
as having Alzheimer's disease,
and they have plaques and tangles
that appear to be either
the causes of cell death
or perhaps the residue,
the aftermath of cell death.
One of the best things you can do
to keep your brain alive
and healthy is simply improving
blood flow to the brain.
Another major mechanism
that's been suggested is the secretion
of a signaling molecule
called brain derived neurotrophic factor.
It's a factor that's made in the brain
that causes neurons to grow.
And that factor has been demonstrated
to improve plasticity in dendrites.
The idea that exercise, by triggering
the secretion of BDNF,
this neurotrophic factor, may lead to
increased plasticity
and improved brain function.
When challenged, we can do more.
And everyone knows this.
And in the absence of challenges
we don't necessarily reach our full potential.
And the current goal
is to try to find ways to stave off
those cognitive losses
by even a few years,
because as we live longer,
having a few years becomes very important.
The biggest problems are not so much
with long-term memories,
but really the short-term memories.
So we can remember
our first kiss when we were in high school
but we may not remember what we had for lunch.
And because we have shrinking of the brain
brain cells actually start to function less efficiently
and do die over time.
The connections between the brain cells diminish
and the neurochemical transmitters
seem to have problems.
So all of those kinds
of physiological changes contribute
to problems with memory as we age.
And what happens is
that memory is basically stored
in little neurochemical packets
in the brain.
So they can be changed and our memories
can deceive us very often.
It's actually possible
to improve our memory ability
with relatively simple strategies
and techniques.
I often recommend that people find things
that they prefer personally.
Things that are mentally challenging
but not too difficult.
So the point is to train but
not strain the brain.
Whether it's crossword puzzles, learning
languages, playing musical instruments.
It's important to try out different things
and do what works for
you and what's enjoyable.
Here’s why there's hope for everybody
and that is the principle of brain plasticity.
Brain plasticity is this idea
that the brain has an
extraordinary capacity
to change or modify
its wiring based on the environment
that you put the brain in,
including the physical environment.
Are you walking a lot?
Are you running?
Are you keeping yourself physically active?
These result in what I call
positive brain plasticity.
What is the difference between a sedentary
brain and an active brain of a runner?
Well, the runner's brain has higher levels
of dopamine and serotonin
boosted every single time
that runner goes for a run.
It elevates general mood state.
Studies that I did in my lab
showed that people
that went to three months of spin class
had overall higher mood states
than people for three months
who played video Scrabble.
Those people in the exercise group
also have much more growth factors
going through their brain.
I like to think of it like a watering
can of growth factors
all up and down your hippocampi.
What's happening?
They’re growing, popping shiny new hippocampal cells
and they're making their prefrontal cortex
work better.
But again, everything is fluid with brain plasticity.
Even if you've been sedentary
all your life, you can start moving
towards what I like to call
bigger, fatter, fluffier and happier brain
with just ten minutes of walking.
We found the same kind of benefits.
Better mood, decreased anxiety, depression
levels and better focus.
Physical activity is the
most transformative thing
that you could do, not only for your body
but for your brain as well.
[TRANSCRIPT_END]