Background:This study explored the feasible efficacy and safety of the Spore Powder of Ganoderma Lucidum (SPGL) for treating patients with Alzheimer disease (AD).Methods:Forty-two eligible patients with AD were recruited. These patients were randomly allocated to an intervention group and a control group equally. The patients in the intervention group underwent SPGL, whereas the subjects in the control received placebo. All patients were treated for a total of 6 weeks. The primary outcome was measured by Alzheimer's disease Assessment Scale-Cognitive (ADAS-cog). The secondary outcomes were measured by the World Health Organization Quality of Life questionnaire (WHOQOL-BREF) and Neuropsychiatric Index (NPI). The adverse events were also recorded during the treatment period.Results:At the end of the treatment, GLSP did not show more encouraging outcomes in symptoms improvement, measured by the ADAS-cog (P = .31), and NPI (P = .79); and quality of life enhancement, measured by the WHOQOL-BREF (physical, P = .62; psychological, P = .69; social relationships, P = .75; environment, P = .82; overall quality of life, P = .74), compared with the control group. In addition, all adverse events were mild, and no significant differences were found between 2 groups.Conclusion:The results of this study did not find the promising efficacy of SPGL for the treatment of AD after 6-week treatment. It may be because of the relative short-term of intervention. Future clinical trials with larger sample size and longer treatment period are urgently needed.