"It's Not Over at Thirty?" When I Gave Up, Brain Research Offered an Unexpected Answer [Experiment Note]

Cambridge University Researchers Analyze Large-Scale Brain MRIs
"Brain Network Efficiency Reaches a Turning Point Around Age 32"

Editor's NoteOne now, or two if you wait. Do you remember the marshmallow experiment that observed children's choices? Sometimes, a simple study can change the way we see life. Let's reinterpret our daily lives through the lens of experimental data.

"Your prefrontal cortex hasn't fully developed yet." This is a phrase you can easily come across when scrolling through TikTok or Instagram. It's a kind of "science meme" (meme·viral internet content) that appears when someone makes an impulsive choice, fails to control their emotions, or feels their life is not yet in order. The prefrontal cortex is the area responsible for higher-order functions such as planning, decision-making, judgment, and emotion regulation.

The background to this meme is the saying, "The brain is fully developed at 25." It often serves as an explanation for the mistakes or immaturity of those under 25. However, after 25, this age becomes a source of pressure-no more excuses. The moment you pass 30, you might feel it's "already too late," making you hesitate to take on new challenges.

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This highlights the gap between biological age and social age. According to a survey conducted last year by the Korean job portal Incruit on the "ideal and maximum age for new university graduates," companies considered the average appropriate age for new hires to be 30.4 for men and 28.2 for women. In other words, one is not considered a full-fledged adult capable of carrying their weight until at least the late twenties. Nevertheless, society already starts treating people as "fully grown adults" from around the mid-twenties. The resulting burden naturally falls on the individual.

"The Brain Remains Adolescent Until Age 32"

Recent neuroscience research points out that the notion of the brain being fully developed at 25 is overly simplistic. In a large-scale brain imaging analysis recently published by researchers at the Medical Research Council (MRC) Cognition and Brain Sciences Unit at the University of Cambridge, approximately 4,200 brain MRIs from infants to people in their 90s were analyzed. This study did not focus on changes in the size of specific brain regions, but rather examined how efficiently different areas were connected. The results showed that the efficiency of brain networks reaches an inflection point around the age of 32.

In particular, between the ages of 9 and 32, the brain's network is actively being reorganized. The researchers referred to this period as the "adolescent period of the brain." Here, adolescence does not mean biological immaturity, but rather a time when structural changes are especially concentrated.

During this period, two network characteristics of the brain are adjusted simultaneously. One is "segregation," the tendency for regions performing similar functions to cluster closely together and become specialized. The other is "integration," in which connections between different networks are strengthened, allowing information to be exchanged more efficiently.

According to the study, both of these characteristics are adjusted in the teens and twenties. Areas with similar functions become more tightly connected, while connections between distant regions also become more refined.

The indicator that particularly drew attention in the research was "small worldness." This concept refers to network efficiency-how quickly information can be transmitted via the shortest possible paths. This indicator increases until the early thirties, then shifts direction. In other words, the period around age 32 is a turning point. Put simply, if the teens and twenties are a time for expanding connections, the thirties are a period for refining those connections.

The researchers also revealed that the human brain experiences several structural turning points throughout life: roughly at ages 9, 32, 66, and 83. Age 32 marks the transition into early adulthood; until age 66, the brain is relatively stable, and from then until 83 marks the boundary of early aging. This suggests that brain changes do not simply stop in the twenties, but continue throughout life, shifting direction at key points.

Neuroplasticity... The Brain Never Stops

While the range of changes in the brain may decrease with age, it never becomes completely fixed. The concept of neuroplasticity shows that the brain retains the ability to form new connections throughout life via growth and reorganization.

High-intensity aerobic exercise, learning foreign languages, and activities like chess that stimulate the brain can help strengthen neural connections. On the other hand, chronic stress can hinder these changes.

Ultimately, if your twenties are a time for expanding connections, your thirties are closer to a period for refining them. Even after that, further turning points continue to arise.

It takes time for concrete to fully set. Likewise, the brain is not an organ that becomes complete at a single moment. Judging one's potential based solely on age may be premature. The new semester is approaching. Perhaps the thing that needs to change most is our attitude.

This content was produced with the assistance of AI translation services.