Limitations
Our review has several limitations. First, this research was limited to
the published and web-accessible literature. Second, our literature
review includes articles in English and Chinese, it is possible that
articles in other languages could supplement the evidence. Finally, the
researchers set up keyword searches, so different researchers may use
different sets of search terms, leading to different articles being
analyzed. However, considering the relatively large number of studies on
AD, it is unlikely that the results will differ significantly.