When I was at school my biology teacher said that the human brain stopped growing in the teenage years, and after that brain cells simply died off. Live long enough and your head would be empty! I did not believe him, and we now know that this sort of thought is nonsense:
https://www.naturalnews.com/2019-10-23-your-brain-doesnt-stop-growing-in-your-90s.html
“Some experts believe that the brain stops producing new brain cells after childhood — but that’s not the case, according to a new study published in the journal Nature Medicine. This study suggests that the brain continues to grow even in your 90s. Researchers from Spain reached this conclusion after looking at the brain tissues donated by 13 individuals who died at the ages of 43 to 87. All donors were neurologically healthy before their deaths. The researchers detected these brain cells by sending antibodies to find the proteins, which are oval for older neurons and longer for younger ones. The researchers found that healthy brains contained new brain cells, which were born in the dentate gyrus, a part of the hippocampus. The hippocampus is a region in the brain that plays a key role in emotion, learning, memory, and mood. However, the number dropped steadily with age. Around the ages of 40 to 70, the number of new brain cells spotted in the dentate gyrus declined from about 40,000 to 30,000 per cubic millimeter (mm3). The number also dropped with the cognitive decline that comes with old age. This indicated that in middle age, nearly 300 fewer neurons per mm3 are made in the dentate gyrus with every advancing year. These findings suggested that even though people lose brain cells in old age, they may still be able to produce new ones to replace them, opening the possibility of creating new memories using new brain cells. After they studied healthy brain tissue, the researchers examined the brains of people who were diagnosed with Alzheimer’s disease before death. The brain tissues were from 45 patients aged 52 to 97. All had new brain cells in the dentate gyrus, including a 97-year-old patient – the oldest person found to still produce new brain cells.”
See, you really are only as old as you think you are, so make sure that you can still think!