Memory Impairment, Dementia, and Alzheimer's Disease in Classical and Contemporary Traditional Chinese Medicine

Objectives: To identify and analyze records of the treatment of dementia and memory disorders in the classical Chinese medical literature that were consistent with the signs and symptoms of Alzheimer's disease (AD), with the aim of determining which traditional medicines have histories of use for these disorders. Methods: Encyclopedia of Traditional Chinese Medicine ( Zhong Hua Yi Dian ), a database of more than 1000 classical and premodern Chinese medical books, was systematically searched. Search terms were identified from dictionaries, medical nomenclatures, guidelines, and specialist clinical manuals on aging, neurology, or brain disorders. Inclusion and exclusion criteria were used to identify citations of conditions whose signs and symptoms were consistent with the clinical features of AD. Passages of text identified by these terms were copied to Microsoft Excel spreadsheets, together with the identity of the source book and all relevant information on the disorder and the intervention. Each distinct passage of text was considered a citation. The frequencies of the traditional formulas used as interventions and their constituent ingredients were calculated. Results: The selection criteria identified 1498 citations of dementia and memory impairments derived from 277 different books written from circa 363 to 1945 AD. In 91 of these citations, memory impairment was associated with aging and was broadly consistent with the clinical features of AD. Although the interventions varied in name, Poria cocos , Polygala tenuifolia , Rehmannia glutinosa , Panax ginseng, and Acorus species consistently appeared as ingredients in multiple formulas for memory impairment in the context of aging. Conclusions: Memory impairment in older age was a recognized condition in the classical literature. Many of the traditional medicines frequently used as ingredients in classical formulas for memory impairment consistent with clinical features of AD remain in contemporary use, and experimental studies suggest biological activities relevant to AD.