The amount of the brain at the age of 20s is about 1200 cc for a man and about 1000 cc for a woman. But nerve cells start to decrease from 20s and the decrease is accelerated at the age of 50, causing shrinkage of the brain and deterioration of the memory. The brain of 70s shrinks by about 180 cc compared to the brain of 20s. in the case of dementia, the brain can shrink by 350 cc (a bottle of beer).
But there are people whose memory declines and people whose memory doesn’t decline. What kind of people’s memory doesn’t decline even if their brain shrinks?
7 people whose age are between 60 and 70 were selected randomly and the shrinkage of their brain were checked. The ratio of the shrinkage was 7.3 % to 9.3 %. Then their memory was checked. The brain ages of 3 people out of 7 people were younger than their ages.
The secret that their memory has not declined is related to seahorses in the head. The seahorses in the head are the hippocampus. The hippocampus retains information coming into the brain temporarily and sends important information required to be retained to the cerebral cortex. (Fig. 1)
It is difficult to make the brain bigger because a lot of nerve cells in the brain die with age. But according to the recent research, it turns out that it is possible to enlarge and increase the nerve cells in the hippocampus.
Substance that makes the hippocampus bigger and stops forgetfulness – BDNF
BDNF stands for Brain-derived neurotrophic factor and is a kind of protein. BDNF is something like feed to activate the nerve cells of the hippocampus. BDNF is expected to make the hippocampus bigger, improve memory and prevent dementia.
In an experiment, BDNF was administered to live nerve cells in the brain and they were cultivated for 3 days. Before the administration of BDNF, they were immature nerve cells (Fig. 2). 1st day they started to move actively and make something like threads. 3rd day they were connected each other and formed network (Fig. 3). Immature nerve cells were activated and formed network to exchange information for 3 days.
How to make BDNF in a daily life
The secretion of BDNF is more in young people and is less in older people. But the method to increase declined BDNF is receiving attention around the world.
The method is makes BDNF using muscles.
It is said that exercises increase BDNF in the hippocampus and the muscles also secretes BDNF and the secreted BDNF is transported to the brain through the blood.
What kind of exercise effectively increases BDNF?
It was found out that aerobic exercise such walking makes the muscles in all the body produce BDNF and increases BDNF by 10 %. The increased BDNF possibly enlarges the hippocampus.
How much walking is necessary to increase BDNF?
2 women whose memory was more than their age checked their BDNF in the blood and tried walking for a week. Their BDNF increased by more than 10 %. If you are concerned about forgetfulness, it is necessary to continue walking for 1 year.