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A human baby's brain at birth averages 369 cm 3 and increases, during the first year of life, to about 961 cm 3, after which the growth rate declines. Brain volume peaks at the teenage years, [34] and after the age of 40 it begins declining at 5% per decade, speeding up around 70. [35]
The cerebral blood volume value of gray matter is about 3.5 +/- 0.4 ml/100g, and the white matter is about 1.7 +/- 0.4 ml/100g. The gray matter is nearly twice that of white matter. [3] In both white and gray matter, cerebral blood volume decreases by about 0.50% per year with increasing age. [4]
The brain volume decreases roughly 5% per decade after forty. It is currently unclear why brain volume decreases with age. However, a few causes may include cell death, decreased cell volume, and changes in synaptic structure.
Brain volume continues to decrease as we age—including the frontal lobe and hippocampus, the areas responsible for cognitive functions—with the rate of shrinkage increasing by around age 60.
A follow-up one year later showed there to have been a marked volumetric decline in those with Alzheimer's and a much smaller decline (averaging 0.5%) in the healthy group. [6] These findings corroborate those of Coffey, who in 1992 indicated that the frontal lobe decreases in volume approximately 0.5–1% per year. [7]
Certain genes influence the volume of key brain regions, which, in turn, could play a role in the development of Parkinson's disease and ADHD, a new study suggests. Parkinson’s, ADHD tied to ...
Structural changes continue during adulthood as brain shrinkage commences after the age of 35, at a rate of 0.2% per year. [4] The rate of decline is accelerated when individuals reach 70 years old. [5] By the age of 90, the human brain will have experienced a 15% loss of its initial peak weight. [6]
Despite the reduced brain matter, the man lived a relatively normal life; he was a married civil servant with two kids. He also scored an IQ of 75 which is considered low but not disabled.