Table 2.

Meta-analysis of RCTs with galantamine and memantine in schizophrenia: efficacy signal

Studies	Positive symptoms	Cognitive symptoms	Negative symptoms
Koola et al. [41], Galantamine 6 studies (n = 226)	Effect size Hedges' g = −0.076 (improved) not significant	Effect size Hedges' g = 0.233, p < 0.001 5 studies: effect size = 0.269	Effect size Hedges' g = −0.107 (improved) not significant
Kishi et al. [42], 2017 Memantine 8 studies (n = 448)	SMD = 0.46, p = 0.07	MD = 3.07, p < 0.0001	SMD = 0.96, p = 0.006
Zheng et al. [43], 2018 Memantine 8 studies (n = 452)	SMD = 0.12 not significant	Weighted MD = 3.09, p < 0.00001	SMD = 0.63, p = 0.009

MD, mean difference; SMD, standardized mean difference. If we combine the meta-analysis findings of galantamine and memantine (let alone synergy), we are likely to get a clinically significant efficacy signal with an effect size of at least 0.8 for positive, cognitive, and negative symptoms.