Table 5.

The results of stratified meta-analysis

Subgroups	Acquisition memory				Retention memory
	Studies	Participants	Effect size, 95 % CI		Studies	Participants	Effect size , 95 % CI
Gensenosides
Rb	2	56	−2.21 [−2.90, −1.53]	P < 0.00001
Rg1	13	290	−2.86 [−3.83, −1.90]		9	200	3.52 [1.95, 5.09]	P = 0.01
Rg2	3	72	−1.31 [−1.82, −0.79]		4	88	1.40 [−0.84, 1.97]
Rg3	3	36	−2.56 [−4.42, −0.71]
Rg5	3	72	−0.46 [−0.96, 0.04]
Dose
1–9 mg	9	216	−1.287 [−1.92, −0.62]	P = 0.009	7	172	1.17 [0.42, 1.93]	P = 0.002
10 mg	9	206	−2.54 [−3.49, −1.59]		3	60	6.54 [1.97, 11.1]
20 mg	5	92	−2.90 [−4.51, −1.28]		3	56	4.30 [2.22, 6.37]
30 mg	1	12	−4.81 [−7.41, 2.20]
Animal species
Mouse	6	136	−1.21 [−1.87, −0.55]	P = 0.008	4	96	1.35 [0.34,2.35]	P = 0.002
Rat	18	390	−2.52 [−3.24, −1.80]		9	192	3.52 [2.02,5.01]
Gender
Male	11	258	−2.65 [−3.66, −1.63]	P = 0.0008	5	256	3.22 [1.66, 6.26]	P = 0.003
Female	5	84	−3.42 [−4.84, −2.00]		5	84	3.78 [1.38, 6.10]
Mixed	3	72	−1.31 [−1.82, −0.79]		3	73	1.22 [0.70, 1.73]
Unclear	5	112	−0.86 [−1.46, −0.26]
Anesthetic agent
Pentobarbital	4	52	−2.22 [−3.40, −1.05]	P = 0.06	1	16	2.53 [1.13, 3.94]	P = 0.87
Chloral hydrate	14	322	−2.66 [−3.52, −1.80]		12	272	2.68 [1.63, 3.72]
Ether	2	40	−1.58 [−2.32, −0.85]
Unclear	4	112	−0.95 [−1.96, 0.06]
Drug delivery
ip	17	366	−2.23 [−2.87, −1.58]	P = 0.68	9	200	1.61 [0.73, 2.49]	P = 0.002
0r	7	160	−1.95 [−3.09, −0.81]		4	88	4.50 [2.92, 6.08]
Study quality
4	2	50	−4.05 [−8.02, −0.08]	P < 0.00001	1	20	2.36 [1.16, 3.56]	P < 0.001
5	3	72	−1.31 [−1.82, −0.79]		6	132	1.22 [2.92, 6.08]
6	11	260	−1.90 [−2.63, −1.17]		4	88	4.50 [2.92, 6.08]
7	2	60	−0.36 [−0.87, 0.15]		6	124	0.52 [0.00, 1.03]
8	6	84	−3.66 [−5.20, −2.13]		3	48	5.98 [−0.63, 12.59]