Our cognitive function is constantly changing, but the underlying structural reasons have been complex. Now, scientists have used MRI data from roughly 3,800 individuals to reveal that the brain's white matter wiring—the connections that facilitate information exchange—undergoes four major structural turning points at the ages of 9, 32, 66, and 83.
Understanding the Shifts:
These turning points mark shifts in the efficiency of the white matter tracts:
- Birth to Age 9: Connections become longer and less efficient, prioritizing the development of a broad range of connections vital for early learning.
- Ages 9 to 32: Efficiency flips; connections become shorter and faster, potentially driven by hormonal changes and supporting the improvement of cognitive skills like planning.
- Age 32 to 66: The longest phase, where efficiency gradually declines again, perhaps due to general wear and tear or major adult lifestyle changes.
- Age 66 onward: Efficiency drops further, with the brain relying more on central "hubs" to maintain communication in later life (83-90), coinciding with increased risk for dementia.
Researchers highlight that understanding these normal phases is critical for future medical applications. According to the team, knowing the typical structural progression will help pinpoint what "deviates" in neurodegenerative and mental health conditions, potentially leading to new treatments.
A Note on the Data: The study cohort was primarily white and sourced from UK and US brain imaging projects, meaning further research is needed to determine if these turning points apply equally to more ethnically and geographically diverse populations.
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