The text reported a total of 24 RCTs (n=2,229). Three studies reported on adults with mild cognitive impairment. Study details in the appendix detailed 25 trials, one of which did not report overall n. For most trials allocation concealment was judged to be unclear.
Healthy older adults performances were significantly improved compared with no contact controls on the three outcomes: paired associate learning (2.71, 95% CI 1.65 to 3.78; three RCTs), immediate verbal recall (0.16, 95% CI 0.06 to 0.26; 23 RCTs) and delayed verbal recall (0.88, 95% CI 0.26 to 1.51; 13 RCTs). Substantial statistical heterogeneity was present for immediate recall (I2=52%) and delayed recall (I2=48%). There were no significant differences in face-name immediate recall (four RCTs), face-name delayed recall (three RCTs), visuospatial memory (three RCTs) or short-term memory (six RCTs).
Healthy adults who received active control versus memory training improved significantly in face-name immediate recall (0.93, 95% CI 0.41 to 1.44; 10 RCTs) and performed less well on visuospatial memory (-0.94, 95% CI -1.66 to -0.22; three RCTs). Statistical heterogeneity was present for immediate recall (I2=45%) and visuo-spatial memory (I2=82%). There were no significant differences in face-name delayed recall (three RCTs), short-term memory (six RCTs), paired associates (four RCTs), immediate recall (19 RCTs) and delayed recall (10 RCTs).
Adults with mild cognitive impairment who received memory training displayed significant improvements in immediate recall versus no contact controls (1.73, 95% CI 0.10 to 3.37; five RCTs) with no heterogeneity, but not for delayed recall (four RCTs). Drug therapy produced significantly better results than memory training for immediate recall (-2.36, 95% CI -11.52 to 6.79; two RCTs) with substantial heterogeneity (I2=72%).