Brain atrophy has the following conditions: 1) normal brain atrophy in the elderly; 2) brain atrophy after damage, such as trauma or surgery; 3) brain atrophy caused by brain hemorrhage and disorders in the blood supply system of the brain. The effect of hyperbaric oxygen therapy for normal senile brain atrophy is not too ideal, because it is the law of life, old age, sickness and death, and it is not very realistic to reverse it forcibly. However, hyperbaric oxygen therapy can reduce some of the symptoms associated with brain atrophy, such as memory loss and mental decline. Through hyperbaric oxygen therapy, blood circulation can be improved and brain function can be promoted, just like normal people usually inhale oxygen, which is good for the body. Therefore, hyperbaric oxygen therapy has some effect on patients with brain atrophy, but the effect is limited. It is not possible to do hyperbaric oxygen therapy after the brain does not shrink or even grow again is not realistic.