. 2022 Jun 30;12:11025. doi: 10.1038/s41598-022-15208-4

Table 6.

Pearson correlations between brain volume and general intelligence g and correlation comparison between sexes; where r is the correlation coefficient; **correlation is significant at the .01 level (2-tailed), *correlation is significant at .05 level (2-tailed), the probability p < .05 is uncorrected; test statistic z for correlation comparison (First transformed the r to Z using the Fisher Z transformations so that they were normally distributed and then applied a Z test where the differences in the Z measured was divided by the standard error. A Z score of greater than ± 1.96 was considered significant), and t statistic for the slope difference.

Correlation between general intelligence g and brain volume	All	Women	Men	Correlation comparison (Women and Men)	Slope comparison (Women and Men)
Mysore Parthenon Cohort Correlation between general intelligence g and brain volume at age 20–22	r = .119 p = .125 N = 166	r = .294 p = .008 N = 80**	r = .152 p = .161 N = 86	z = .94 p = .174	t = 1.088 p = .278
ACONF Correlation between childhood general intelligence g^a and brain volume at age 60–66	r = .160* p = .013 N = 238	r = .378 p < .001 N = 122**	r = .137 p = .141 N = 116	z = 1.98 p = .024	t = 3.634 p < .001
ACONF Correlation between general intelligence g at age 60–66 and brain volume at the same age (60–66)	r = .095 p = .142 N = 238	r = .309 p < .001 N = 122**	r = .098 p = .295 N = 116	z = 1.68 p = .046	t = 1.816 p = .071
UK Biobank Correlation between general intelligence g and brain volume at age 60–66^b	r = .207 p < .001 N = 1969**	r = .232 p < .001 N = 1062**	r = .151* p < .001 N = 907	z = 1.86 p = .032	t = 2.346 p = .019
UK Biobank Correlation between general intelligence g and brain volume at age 45–79	r = .173 p < .001 N = 6659**	r = .189 p < .001 N = 3505**	r = .145 p < .001 N = 3154**	z = 1.84 p = .033	t = 2.560 p = .010

Correlation between general intelligence g and brain volume

All

Women

Men

Correlation comparison (Women and Men)

Slope
comparison
(Women and
Men)

Mysore Parthenon Cohort

Correlation between general intelligence g and brain volume at age 20–22

r = .119

p = .125

N = 166

r = .294**

p = .008

N = 80

r = .152

p = .161

N = 86

z = .94

p = .174

t = 1.088

p = .278

ACONF

Correlation between childhood general intelligence g^a and brain volume at age 60–66

r = .160*

p = .013

N = 238

r = .378**

p < .001

N = 122

r = .137

p = .141

N = 116

z = 1.98

p = .024

t = 3.634

p < .001

ACONF

Correlation between general intelligence g at age 60–66 and brain volume at the same age (60–66)

r = .095

p = .142

N = 238

r = .309**

p < .001

N = 122

r = .098

p = .295

N = 116

z = 1.68

p = .046

t = 1.816

p = .071

UK Biobank

Correlation between general intelligence g and brain volume at age 60–66^b

r = .207**

p < .001

N = 1969

r = .232**

p < .001

N = 1062

r = .151*

p < .001

N = 907

z = 1.86

p = .032

t = 2.346

p = .019

UK Biobank

Correlation between general intelligence g and brain volume at age 45–79

r = .173**

p < .001

N = 6659

r = .189**

p < .001

N = 3505

r = .145**

p < .001

N = 3154

z = 1.84

p = .033

t = 2.560

p = .010

The significant values are shown in bold.

^aChildhood general intelligence g data are not contemporaneous with MRI acquisition as for the rest of data.

^bThe UK Biobank group 60–66 y was retrieved from the UK Biobank data (45–79 y) in order to match the ACONF age group for a better comparison with an increased number of participants.