There are two peak periods in the development of the number of neurons in the brain, namely, at the age of 2-5 years and puberty, with a gradual decrease in the number of neurons after the age of greater than 25 years. The first period of neuron number growth is after birth, and the number reaches its peak at the age of 2~5 years. At this time, the weight of the brain is about 1/4 of that of an adult, and the control ability of the cerebral cortex gradually increases, such as the regularity of life and the ability to take care of oneself, the use of language, and the advancement of the ability to listen and read. The 2nd period of growth in the number of neurons is puberty, when the number of neurons increases mainly in higher regions such as the prefrontal lobe, and is completed by about 25 years of age. Generally when the human body is older than 25 years old, the neurons in the brain will gradually decrease as the environment changes, diseases occur, etc. It is important to take care of nutritional supplements, good sleep and proper guidance during this critical period of brain development.