What is the difference between a 18 year old brain and a 17 year old brain?

Anonymous
I have seen lots of images and articles comparing 21 year old brains with 17 year old brains and what not, there's clearly differences between the two. And I've seen it done with other ages too but I have yet to see the differences between an 18 year old brain and 17 year old brain. So can someone please tell me what the differences are? like I heard there is a decrease of grey matter?

I'm currently trying to figure out a lot about the brain and started doing research into how it develops.
What is the difference between a 18 year old brain and a 17 year old brain?
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