What Is Brain Shrinkage? Can The Brain Grow New Neurons?

The problem with brain shrinkage, also known as cerebral atrophy, is that it only measures changes in volume. That isn't very helpful because that doesn't tell us what's dying back. The usual suspect are neurons. If that's the case, it's not a big deal. However, if it's the glial cells that are under attack, that's a major problem because that will adversely affect the whole brain because they have four important functions: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy and remove the carcasses of dead neurons (clean up).

Ageing and the brain

So is this bad thing? Maybe, maybe not.

According to the American Psychological Association, mental decline is neither inevitable nor unavoidable:

Memory Changes in Older Adults

However, there is at least one occasion where the brain recovers from cerebral atrophy - after pregnancy

The Incredible Shrinking Brain

Change in brain size during and after pregnancy: study in healthy women and women with preeclampsia

Note that the studies show a decrease in brain size during pregnancy when compared with after which means that the brain grows back.

This means that the wife of Feodor Vassilyev allegedly went through 27 consecutive incidences of cerebral atrophy and recovery without apparent harm or long term damage. Of course, that would have to be confirmed by further research into the records of the Monastery at Nikolsk which claimed to have recorded each birth.

Most prolific mother ever

However, putting this extreme example to one side, it is known that many women have had multiple pregnancies without mental decline.

I find this very exciting. It means that the brain can recover from cerebral atrophy and that it isn't the death sentence that some have feared.

The problem with the concern about cerebral atrophy is the incorrect notion that brain size matters. We believe that our intelligence is directly related to brain size and that this was the thing that separated us from all of the other animals. It isn't and it doesn't. Human brains vary between 1.3 to 1.5 kg (2.9 to 3.3 lb). A bottlenose dolphin has a slightly larger brain 1.5 to 1.7 kg (3.3 to 3.7 lb). An elephant's brain is about 3 times larger at 5 kg (11 lb) and sperm whales are about 5 times larger at 8 kg (18 lb). To make matters worse, brain sizes a lot smaller than 1.3 kg have been measured in some people suffering from hydrocephaly without an apparent loss of ability.

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