MRI Analysis of 4,216 Individuals
Five Distinct Phases of Brain Development and Aging
Early Aging Begins at 66, Late Aging at 83
A study has found that the human brain undergoes five distinct stages of development and aging throughout life, with inflection points occurring on average at the ages of 9, 32, 66, and 83.
The Wall Street Journal (WSJ) reported on the 23rd (local time), citing a paper published in the journal Nature Communications by a research team from the University of Cambridge.
The research team, led by Alexa Mosley, a researcher at the University of Cambridge who served as both the first and corresponding author, analyzed brain MRI data from 4,216 individuals aged 0 to 90. They published a paper titled "Topological Turning Points in the Human Lifespan." The team observed the brain's white matter (bundles of nerve fibers in the central nervous system, such as the brain and spinal cord) and constructed an "average brain" for each year of age, analyzing how the connectivity of the average brain changes with age.
The results showed that the brain's connectivity patterns undergo distinct changes at the average ages of 9, 32, 66, and 83. First, from birth to age 9 is the "childhood development period" of the brain. During this stage, the brain grows rapidly in size, but connections that are unused or inefficient-among the many that are excessively formed in a newborn's brain-are "pruned" away.
The "adolescence" stage of the brain begins around age 9 and continues until about age 32. During this period, the efficiency of brain connections increases, and the ability to transmit information between brain regions improves. From age 32 to 66 is considered the "stabilization period," during which brain regions tend to become more isolated from one another, and the structure of brain connectivity becomes more fixed.
From age 66 to 83, the brain enters the "early aging" stage. Some regions of the brain become more tightly bound together, forming "modules," but the connections between these modules begin to deteriorate, and white matter degeneration also begins. As a result, cognitive abilities may decline. In the "late aging" stage, which begins around age 83, connections between different regions of the brain weaken further. Instead of using the entire brain comprehensively when making decisions, there is a pronounced tendency to rely only on a small number of frequently used pathways.
The research team explained that this study could help clarify why brain-related diseases tend to emerge at certain ages and what efforts are needed for healthy aging. For example, most autism diagnoses are made in childhood, and about three-quarters of mental illnesses develop in the early twenties. In addition, Alzheimer's disease is known to manifest primarily during the early aging stage.
However, experts emphasized that the timing of these brain changes varies greatly among individuals, and the ages presented in the paper are only averages, not absolute standards.
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