Image from scmp.com

As early as 5 years of age, our brains have reached 90% of their potential volume. However, we all know that our brains continue to develop for many years; in fact, our brains continue evolving until death. So why then, do many people worry about cognitive decline with aging, and are their fears misplaced?

While it is evident and typical that specific cognitive functions decline with age, this is not necessarily associated with a cease in brain growth or weakened memory formation. General intelligence is complicated. It can be subdivided into two categories: crystallized and fluid intelligence.

Fluid intelligence allows you to solve problems without experience or knowledge—this type of intelligence peaks early in adulthood and declines later in life. Crystalized intelligence uses experience and prior knowledge to assess future relationships. This type of intelligence increases until approximately 60 years of age and then declines slightly. Therefore, skills like vocabulary, comprehension of new information, and arithmetic improve long after the brain ceases to grow in size and remain relatively stable throughout life. Other crystalized skills, such as conflict resolution and emotional regulation can continue to improve beyond 60 years of age.

The brain is an evolving organ as our lives go on. There might not be a moment in which our brains operate at maximum cognitive function in every specific area. So, next time you lose your keys, remember that just because your brain has stopped growing does not mean that your cognitive function is declining. 

https://azpbs.org/2017/11/early-childhood-brain-development-lifelong-impact/

https://www.nm.org/healthbeat/healthy-tips/ten-surprising-facts-about-your-brain

https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=3051

https://www.simplypsychology.org/fluid-crystallized-intelligence.html
https://www.psychologicalscience.org/observer/the-cognitive-upside-of-aging