Hello, mental decline is not memory decline. According to the research of Yangshengtang and the speed reading memory experts of Jingyingte, it is normal for people's memory to decline from the age of 20, but their intelligence has not declined. You can eat more foods rich in DHA, such as eggs, meat, fish, etc., and pay attention to giving your brain a moderate rest. In addition, your memory and intelligence will also be improved by activating your brain or using speed reading memory tools to assist your brain activities and playing chess. As the saying goes, the more you use your brain, the smarter you are. If you are satisfied, please accept it. Thank you.