Yokukansan
Yokukansan is a standard recipe or prescription from traditional Chinese medicine used widely in Eastern Asian countries including China, Taiwan, North and South Koreas and Japan. There are some classical text books describing YKS for example 『保嬰金鏡録』, 『保嬰撮要』 by 薛鎧 and others. But only 薛己 described it as "愚製" in his book, so that 薛己 is probably the originator of this recipe. Yokukansan contains an exactly measured mixture of dried herbs, 3g of Atractylodes macrocephala macrocephala Koidz. in China or 4 g of Atractylodes lanceae rhizoma in Japan, 4 g of Poria, 3 g of Cnidii rhizoma, 3 g of Angelicae radix, 2 g of Bupleuri radix, 1.5 g of Glycyrrhizae radix, and 3 g of Uncariae uncis cum ramulus.
薛鎧, the father of 薛己 explained this recipe in his text book 保嬰撮要 thus:
"This recipe improves convulsion, fever, gnash, unsettled state of mind, and terror caused by enervation. Also, it is effective for vomiting, feeling of fullness, appetite loss and dysnystaxis caused by stress".
The name of the text book 保嬰撮要 means "The essence of Pediatrics", so 薛鎧 and his son 薛己 may have used YKS mainly for children.
In 2005, the efficacy of YKS for behavioral and psychological symptoms of dementia such as hallucination, delusion, easy to anger and so on in demented patients was reported in randomized controlled study, and meta-analysis showed the same result. Moreover, YKS is also effective for visual hallucination in Lewy body disease. Therefore, YKS Is widely applied to BPSD and DLB treatment in Japan. The sale of YKS by Tsumura company was 5903000000 Japanese yen in 2017. It is the runners up in all traditional herbal medicines for medical use in Japan.
Though 227 medical papers are hit in PubMed on 27 March 2021, the whole mechanisms of YKS efficacy are still not perfectly clear. At least, there are many reports suggesting that it may have effect on serotonin receptors and glutamate transporters. Further mechanisms will be reported in the future.