In this meta-analysis, compared with the control group, APP ratio, ADAM10, ADAM10/actin, Na + -K + -ATPase in platelets of AD group significantly decreased; HMW tau/LMW tau, adenosine A2 receptor, MAO-B, NO and ONOO− productions significantly increased; BACE-1, PSEN-1, 5-HT, Ca2+, DPH, TMA-DPH had no significant difference. The gene discussed is PSEN1; the disease is Alzheimer disease.