title: The Association between IGF-1 Polymorphisms, IGF-1 Serum Levels, and Cognitive Functions in Healthy Adults: The Amsterdam Growth and Health Longitudinal Study.
abstract: Several studies have demonstrated an association between polymorphisms in the insulin-like growth factor-1 (IGF-1) gene and IGF-1 serum levels. IGF-1 levels have been associated with cognitive functioning in older persons and growth hormone deficient patients. The present study investigates whether IGF-1 polymorphisms, IGF-1 levels, and cognition are interconnected in healthy adults. Data of 277 participants (mean age: 42.4 years) of the Amsterdam Growth and Health Longitudinal Study on IGF-1 promoter polymorphisms, IGF-1 serum level, spatial working memory (SWM), paired associate learning (PAL), and IQ tests were analyzed. (M)ANOVAs were applied to confirm the associations between IGF-1 polymorphisms and IGF-1 levels and between IGF-1 levels and cognition. Three groups were distinguished based on specific IGF-1 polymorphism alleles: a homozygote 192 bp/192 bp genotype, a heterozygote 192 bp/x genotype, and a noncarrier x/x genotype. Although different IGF-1 levels were found for the three genotypes, performance on all cognitive tasks and IQ measures was similar. Despite the associations between IGF-1 polymorphisms and IGF-1 levels, no association was found between cognition and IGF-1 levels. It seems that IGF-1 does not play a role in the cognitive performance of healthy middle-aged adults. Possible, IGF-1 fulfills a more developmental and protective role in cognition which becomes apparent during childhood, old-age, or disease.
authors.affiliation: Department of Clinical Neuropsychology, VU University, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands ; Department of Epidemiology and Biostatistics, The EMGO Institute for Health and Care Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
authors.forename: Carmilla M M
authors.initials: CM
authors.lastname: Licht
authors.affiliation: Department of Internal Medicine, Endocrine Section, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
authors.forename: Lise C
authors.initials: LC
authors.lastname: van Turenhout
authors.affiliation: Department of Clinical Neuropsychology, VU University, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
authors.forename: Jan Berend
authors.initials: JB
authors.lastname: Deijen
authors.affiliation: Work and Employment Division, Netherlands Organization for Applied Scientific Research (TNO), Polarisavenue 151, 2132 JJ Hoofddorp, The Netherlands.
authors.forename: Lando L J
authors.initials: LL
authors.lastname: Koppes
authors.affiliation: Department of Public and Occupational Health, EMGO Institute for Health and Care Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands ; Body@Work, Research Center on Physical Activity, Work and Health, TNO-VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
authors.forename: Willem
authors.initials: W
authors.lastname: van Mechelen
authors.affiliation: Department of Epidemiology and Biostatistics, The EMGO Institute for Health and Care Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands ; Department of Health Sciences, Faculty of Earth and Life Sciences, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
authors.forename: Jos W R
authors.initials: JW
authors.lastname: Twisk
authors.affiliation: Department of Clinical Neuropsychology, VU University, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands ; Department of Internal Medicine, Endocrine Section, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
authors.forename: Madeleine L
authors.initials: ML
authors.lastname: Drent
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