Table 2

Pooled weighted effect sizes and heterogeneity statistics of all cognitive domains and frequently used neuropsychological tests

Cognitive domainHedges’ g95% CIKNQp (Q)I2 (%)Fail-safe NTolerance level
Visuoconstructive functions0.840.36 to 1.31620215.420.0096815440
 Recalculation w/o outlier0.630.36 to 0.9051834.430.3510NANA
Psychomotor speed0.640.43 to 0.851661334.900.00357349390
 Recalculation w/o outlier0.690.49 to 0.891556125.690.0346NANA
 Neuropsychological tests
  TMT, part A0.500.23 to 0.7683329.340.2325NANA
  Stroop, part 1 and 20.620.24 to 1.00623419.440.00274NANA
  SDMT0.730.45 to 1.0162364.670.460NANA
Fluency0.580.50 to 0.6725121721.240.62039 612135
 Recalculation w/o motor bias0.560.43 to 0.701276112.970.3015NANA
 Neuropsychological tests
  Letter fluency0.680.55 to 0.8223112028.110.1722NANA
  Category fluency0.550.41 to 0.68158496.410.960NANA
Language0.570.41 to 0.721981031.460.03436897105
 Recalculation w/o motor bias0.560.40 to 0.721877631.250.0246NANA
 Neuropsychological tests
  Naming test0.600.42 to 0.781669419.210.2022NANA
Social cognition0.550.34 to 0.7662529.240.104635840
MMSE0.520.37 to 0.681795618.870.2815453795
Executive functions0.490.36 to 0.62311587117.16<0.0017418 687165
 Recalculation w/o motor bias0.410.27 to 0.5522120170.90<0.00169NANA
 Neuropsychological tests
  WCST0.500.28 to 0.721769890.25<0.00182NANA
  Stroop, part 30.750.30 to 1.2014813117.44<0.00189NANA
  TMT, part B0.890.36 to 1.421045799.37<0.00191NANA
  Brixton0.18−0.27 to 0.63546318.370.00178NANA
Delayed verbal memory0.470.27 to 0.681664033.810.00456190090
 Recalculation w/o outlier0.520.32 to 0.721558625.140.0344NANA
 Neuropsychological tests
  AVLT0.470.21 to 0.741146023.050.0157NANA
Immediate verbal memory0.460.33 to 0.591975522.390.21206916110
 Neuropsychological tests
  AVLT0.580.33 to 0.82935812.160.1434NANA
Attention0.420.33 to 0.5214108614.500.3410558280
 Neuropsychological tests
  Digit span0.330.20 to 0.46116539.070.530NANA
Verbal IQ0.280.11 to 0.46104855.690.77047060
Visual memory0.210.07 to 0.351759314.790.54088195
 Recalculation w/o motor bias0.230.08 to 0.381446312.630.480NANA
Visuoperceptive functions0.17−0.04 to 0.39940415.960.0450NANA
  • Hedges’ g: effect size; 95% CI: 95% CI of effect size; K: number of studies; N: number of participants; Q: heterogeneity between studies within cognitive domain; p (Q): p value for heterogeneity; I2: percentage of heterogeneity caused by study differences (Q—degrees of freedom/Q×100%); Fail-safe N: number of non-significant studies needed to obtain a non-significant effect size (p=0.05), not calculated for visuoperceptive functions, because this domain showed no significant effect size; Tolerance level: estimated number of existing unpublished studies (5k+10); Recalculation w/o motor bias: effect size after exclusion of tests with possible bias due to motor impairment, w/o: without; Recalculation w/o outlier: effect size after exclusion of the main outlier in domains with substantial heterogeneity, w/o: without. For executive functions, no outlier could be identified. NA: not applicable. Effect sizes of neuropsychological tests that were administered in ≥5 studies were also calculated. TMT: trail making test; Stroop, part 1 and 2: Word-reading and colour-naming of the Stroop test; SDMT: symbol digit modalities test; WCST: Wisconsin card sorting test; Stroop, part 3: Colour word interference of the Stroop test; Brixton: Brixton spatial anticipation test; AVLT: auditory verbal learning test. MMSE, mini mental state examination.