When the loss of brain tissue reaches a certain level, the impact on memory becomes more pronounced. Until then, the brain can compensate to some extent.
Researchers behind the study, published in Nature Communications, explain that the issue is not age alone. What matters is how much structural burden has accumulated in the brain over time.
Only when this burden becomes sufficiently large does memory loss begin to accelerate.
A large data set
The results are based on analyses of more than 10,000 MRI scans and over 13,000 memory tests.
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In total, 3,700 cognitively healthy adults took part in 13 international longitudinal studies, according to researchers from the Hinda and Arthur Marcus Institute for Aging Research.
The extensive data set makes it possible to compare developments across many different individuals over many years.
This strengthens the conclusions and reduces the risk of random variation.
More than one area
The study also shows that memory loss cannot be explained by changes in a single part of the brain.
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The hippocampus is important, but both superficial and deeper brain structures also play a role.
The findings suggest that memory depends on the interaction of the entire brain.
Researchers believe that this knowledge can be used to identify at-risk individuals earlier and to tailor preventive efforts in line with an aging population.
Sources: Science Daily, and Nature Communications.
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