bigger and better than other living things. For example, the human brain is more than three times larger than a chimp’s in relation to the body, which leads to it having a relatively higher energy demand. This means the human brain uses well over 25% of the body’s energy when at rest, compared to 10% for other primates (which do not shrink with age). As we age, just keeping up with the brain’s energy needs becomes difficult and takes its toll on the cellular and molecular levels in the human brain. This includes a decline in the efficiency of the mitochondria, the energy storehouses of living cells, as well as damage from oxidative stress, the result of oxygen-containing molecules that are produced during cell metabolism.
So, as we grow older, our brain slowly and surely shrinks, exposing us to age-related neurodegenerative disorders, such as memory loss, Alzheimer’s disease and dementia. MRI scans shows that the reduction in size is quite dramatic, with some regions shrinking by as much as 25% by the age of 80, showed a study in Proceedings of the National Academy of Sciences.
Even the healthiest of brains show the effects of aging — measured through the build-up of amyloid-beta plaque deposits and loss of neural connections — especially in the frontal lobe and the hippocampus, which are regions linked to learning and memory.
Now it seems even shrinkage has a gender bias, with women’s brains ageing faster than men’s. And this has nothing to do with women living longer. When people age, some genes become more active while others slow down. In the human brain, these changes can be seen through the “transcriptome”, which is a set of RNA molecules that control the activity of genes within a population of cells.
Last week, computational biologists at the University of California, Berkeley, found that the pattern of gene activation and deactivation that occurs with ageing appeared to progress faster in women than in men.
The Berkeley team then compared the expression of more than 13,000 genes in the brain. In one region — the superior frontal gyrus — they found 667 genes that were expressed differently in men and women during ageing. Of those, 98% were skewed towards faster ageing in women, and had previously been linked to overall decline in brain power.
The good news is that this gender-based decline can be reversed. Since the study showed only about half the women showed accelerated age-related changes, the researchers said the cause was environmental rather than purely biological. They blamed it on higher stress, which in the past has shown to induce similar changes to brain transcriptome in monkeys.
We’ve all been told that constantly challenging the brain — by travelling to new countries, learning new skills, doing puzzles and exercising to increase blood supply to the mind, de-stressing — can slow the decline.
Nintendo even has a brain-training bestselling franchise called Brain Age: Train Your Brain in Minutes a Day, which has sold more than 20 million copies worldwide. It’s a brilliant reminder that our brains start slowing down at the cruelly young age of 20, but you can even reverse the ageing by using it. The brain is a machine that works best when used, so exercising it both physically and mentally is the most effective way to keep it sharp and supple as you grow older.