The Association between IGF-1 Polymorphisms, IGF-1 Serum Levels, and Cognitive Functions in Healthy Adults: The Amsterdam Growth and Health Longitudinal Study

Table 1

Sample characteristics.

	Homozygotic; 192/192; 𝑁=109	Heterozygotic; 192/x; 𝑁=138	Noncarrier; x/x; 𝑁=31	𝑃^∗
Sociodemographics
Age, mean years (SD)	42.4 (0.8)	42.3 (0.7)	42.4 (0.9)	0.76
% female	56.0	50.7	51.6	0.71
BMI, mean kilograms/meters^2 (SD)	24.5 (3.7)	24.8 (3.8)	24.6 (2.7)	0.78
Alleles
176, 𝑁	0	1	1	—
186, 𝑁	0	0	0	—
188, 𝑁	0	9	7	—
190, 𝑁	0	16	12	—
192, 𝑁	218	138	0	—
194, 𝑁	0	84	25	—
196, 𝑁	0	22	14	—
198, 𝑁	0	6	3	—
IGF-1, mean nml/liter (SD)	22.6 (5.4)	24.4 (5.5)	25.1 (5.4)	0.01

∗Based on 𝜒² and ANOVA statistics for dichotomous or categorical and continuous measures, respectively.
SD: standard deviation, BMI: body mass index, PAL: paired associates learning, SWM: spatial working memory, GIT: Groninger intelligentietest test, and NLV: Nederlandse Leestest voor Volwassenen.