Study	Reason for exclusion
Cheng 2008	It was not placebo controlled. Comparator interventions were conventional therapy
Ding 2009	It was not placebo controlled. Comparator interventions were nimodipine
Jiang 2009	It was not placebo controlled. Comparator interventions were conventional therapy
Lin 2008	It was a cross‐over trial
Ma 1998	It was not a randomised controlled trial
Wang 2005	It was not placebo‐controlled. Comparator interventions were conventional therapy
Xue 2005	The participants did not have mild cognitive impairment