Comparison 3. Group cognitive stimulation versus no cognitive stimulation (number of sessions): post‐treatment.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
3.1 Cognition	27	1637	Std. Mean Difference (IV, Random, 95% CI)	0.43 [0.26, 0.59]
3.1.1 20 or more group sessions of CS during one to twelve months	12	615	Std. Mean Difference (IV, Random, 95% CI)	0.42 [0.16, 0.67]
3.1.2 Less than 20 group sessions of CS during one to twelve months	15	1022	Std. Mean Difference (IV, Random, 95% CI)	0.43 [0.22, 0.65]
3.2 ADAS‐Cog	17	1168	Mean Difference (IV, Random, 95% CI)	2.66 [1.12, 4.20]
3.2.1 20 or more group sessions of CS during one to twelve months	7	418	Mean Difference (IV, Random, 95% CI)	4.18 [‐0.28, 8.64]
3.2.2 Less than 20 group sessions of CS during one to twelve months	10	750	Mean Difference (IV, Random, 95% CI)	2.52 [1.22, 3.83]
3.3 MMSE	21	1325	Mean Difference (IV, Random, 95% CI)	2.16 [1.58, 2.74]
3.3.1 20 or more group sessions of CS during one to twelve months	11	554	Mean Difference (IV, Random, 95% CI)	2.51 [1.20, 3.83]
3.3.2 Less than 20 group sessions of CS during one to twelve months	10	771	Mean Difference (IV, Random, 95% CI)	2.11 [1.51, 2.72]
3.4 Quality of Life: self‐report	13	1058	Mean Difference (IV, Random, 95% CI)	1.97 [0.47, 3.47]
3.4.1 20 or more group sessions of CS during one to twelve months	4	281	Mean Difference (IV, Random, 95% CI)	1.33 [‐1.14, 3.79]
3.4.2 Less than 20 group sessions of CS during one to twelve months	9	777	Mean Difference (IV, Random, 95% CI)	2.24 [0.13, 4.36]