Table 2

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

Cognitive domain	Hedges’ g	95% CI	K	N	Q	p (Q)	I² (%)	Fail-safe N	Tolerance level
Visuoconstructive functions	0.84	0.36 to 1.31	6	202	15.42	0.009	68	154	40
Recalculation w/o outlier	0.63	0.36 to 0.90	5	183	4.43	0.35	10	NA	NA
Psychomotor speed	0.64	0.43 to 0.85	16	613	34.90	0.003	57	3493	90
Recalculation w/o outlier	0.69	0.49 to 0.89	15	561	25.69	0.03	46	NA	NA
Neuropsychological tests
TMT, part A	0.50	0.23 to 0.76	8	332	9.34	0.23	25	NA	NA
Stroop, part 1 and 2	0.62	0.24 to 1.00	6	234	19.44	0.002	74	NA	NA
SDMT	0.73	0.45 to 1.01	6	236	4.67	0.46	0	NA	NA
Fluency	0.58	0.50 to 0.67	25	1217	21.24	0.62	0	39 612	135
Recalculation w/o motor bias	0.56	0.43 to 0.70	12	761	12.97	0.30	15	NA	NA
Neuropsychological tests
Letter fluency	0.68	0.55 to 0.82	23	1120	28.11	0.17	22	NA	NA
Category fluency	0.55	0.41 to 0.68	15	849	6.41	0.96	0	NA	NA
Language	0.57	0.41 to 0.72	19	810	31.46	0.03	43	6897	105
Recalculation w/o motor bias	0.56	0.40 to 0.72	18	776	31.25	0.02	46	NA	NA
Neuropsychological tests
Naming test	0.60	0.42 to 0.78	16	694	19.21	0.20	22	NA	NA
Social cognition	0.55	0.34 to 0.76	6	252	9.24	0.10	46	358	40
MMSE	0.52	0.37 to 0.68	17	956	18.87	0.28	15	4537	95
Executive functions	0.49	0.36 to 0.62	31	1587	117.16	<0.001	74	18 687	165
Recalculation w/o motor bias	0.41	0.27 to 0.55	22	1201	70.90	<0.001	69	NA	NA
Neuropsychological tests
WCST	0.50	0.28 to 0.72	17	698	90.25	<0.001	82	NA	NA
Stroop, part 3	0.75	0.30 to 1.20	14	813	117.44	<0.001	89	NA	NA
TMT, part B	0.89	0.36 to 1.42	10	457	99.37	<0.001	91	NA	NA
Brixton	0.18	−0.27 to 0.63	5	463	18.37	0.001	78	NA	NA
Delayed verbal memory	0.47	0.27 to 0.68	16	640	33.81	0.004	56	1900	90
Recalculation w/o outlier	0.52	0.32 to 0.72	15	586	25.14	0.03	44	NA	NA
Neuropsychological tests
AVLT	0.47	0.21 to 0.74	11	460	23.05	0.01	57	NA	NA
Immediate verbal memory	0.46	0.33 to 0.59	19	755	22.39	0.21	20	6916	110
Neuropsychological tests
AVLT	0.58	0.33 to 0.82	9	358	12.16	0.14	34	NA	NA
Attention	0.42	0.33 to 0.52	14	1086	14.50	0.34	10	5582	80
Neuropsychological tests
Digit span	0.33	0.20 to 0.46	11	653	9.07	0.53	0	NA	NA
Verbal IQ	0.28	0.11 to 0.46	10	485	5.69	0.77	0	470	60
Visual memory	0.21	0.07 to 0.35	17	593	14.79	0.54	0	881	95
Recalculation w/o motor bias	0.23	0.08 to 0.38	14	463	12.63	0.48	0	NA	NA
Visuoperceptive functions	0.17	−0.04 to 0.39	9	404	15.96	0.04	50	NA	NA

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.