Is it true that the average 70-year-old’s brain is the same size as a 3-year-old’s brain?
If so, does “size” in this context refer to the brain’s volume or to the number of neurons? What causes this shrinkage to occur? What measures can be taken to protect against this?
Thanks.
A child’s brain grows as they do, and gray matter volume does decline in later years. However, I find it hard to believe just based on the size of my 3 year old daughter’s head. I’d have to see some sort of scientific study where they shake a 70 year old’s head to see if it rattles.
I’m not exactly certain, but I recall reading it in one of the “science” magazines I flip through at the local bookstore some months ago (Scientific American, Discovery, New Scientist, or something like that).
As I recall, the 70-year-old brain size quote was pulled from the article and highlighted in big, bold letters. This was right around the time of the election, so the political impications were rather obvious: a vote for McCain is equivalent to a vote for your toddler.
What does brain size matter, anyway? I thought phrenology was out of fashion. It’s what you do with your neurons, and not how big your brain is, that counts.
There’s a great degree of variability in brain size with aging, that keeps up even when people reach the age of 100. So many older folks have brain sizes the same as normal young adults. From Clinical Neurology of Aging
First of all, don’t underestimate the size of a 3-year-old’s brain. Children’s heads are disproportionately large, compared to their bodies. And as adults age, their bodies (not their heads, AFAIK) tend to shrink. So there may be some truth to the OP. Not that head size, or even brain size, has to do with anything though.
I remember reading a 1970’s edition of the Guinness Book of Records where the largest normal human brain and the smallest normal, adult human brain ever recorded both belonged to 19th century Russian novelists (can’t recall the names). Apparently measuring brain size post-mortem was a common occurence in the literary circles of Zsaric Russia.