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Clarke RB, Okholm GT, Mortensen EL, Osler M, Wimmelmann CL, Sørensen TIA. Intelligence and obesity during the obesity epidemic. Sci Rep 2025; 15:4519. [PMID: 39915509 PMCID: PMC11803092 DOI: 10.1038/s41598-025-87402-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 01/20/2025] [Indexed: 02/09/2025] Open
Abstract
Several studies conducted during the last 50 years have shown that lower intelligence is associated with a higher body mass index (BMI). During this period, the prevalence of obesity and overweight has increased considerably. We investigated whether this increase has altered the relation between intelligence and BMI by studying two cohorts of 419,319 conscripts, born 1939-1959 and 1983-2001, examined in the same geographical districts in Denmark. While the prevalence of obesity increased from 0.8% in the early to 6.7% in the late cohort, the two cohorts showed essentially the same pattern of relations between intelligence test scores (ITS), prevalence of obesity and overweight (including obesity), and BMI. The prevalence of obesity and overweight and BMI was higher at any ITS value in the late than in the early cohort, but inversely associated with ITS in both cohorts. The ITS displayed inverse J-shaped associations with BMI, with ITS peaking around a BMI of 20 kg/m2 and declining with higher BMI, although with a somewhat steeper decline in the early than in the late cohort. Thus, irrespective of the increase in prevalence of obesity and overweight and in BMI, the pattern of inverse relations between intelligence and higher BMI levels was maintained.
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Affiliation(s)
- Rebecca B Clarke
- National Institute of Public Health, Faculty of Health Sciences, University of Southern Denmark, Copenhagen, Denmark.
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Gunhild T Okholm
- National Institute of Public Health, Faculty of Health Sciences, University of Southern Denmark, Copenhagen, Denmark
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Erik L Mortensen
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Merete Osler
- Centre for Clinical Research and Prevention, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark
- Section of Epidemiology, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Thorkild I A Sørensen
- Section of Epidemiology, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Centre for Childhood Health, Copenhagen, Denmark
- Section of Genomic Physiology and Translation, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Grønkjær M, Mortensen EL, Wimmelmann CL, Flensborg-Madsen T, Osler M, Okholm GT. The Danish Aging and Cognition (DanACo) cohort. BMC Geriatr 2024; 24:238. [PMID: 38454360 PMCID: PMC10921587 DOI: 10.1186/s12877-024-04841-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 02/22/2024] [Indexed: 03/09/2024] Open
Abstract
BACKGROUND With aging populations worldwide, identification of predictors of age-related cognitive decline is becoming increasingly important. The Danish Aging and Cognition Cohort (DanACo) including more than 5000 Danish men was established to investigate predictors of age-related cognitive decline from young adulthood to late mid-life. CONSTRUCTION AND CONTENT The DanACo cohort was established through two separate data collections with identical designs involving a follow-up examination in late mid-life of men for whom intelligence test scores were available from their mandatory conscription board examination. The cohort consists of 5,183 men born from 1949 through 1961, with a mean age of 20.4 years at baseline and a mean age of 64.4 years at follow-up. The baseline measures consisted of height, weight, intelligence test score and educational level collected at the conscription board examination. The follow-up assessment consisted of a re-administration of the same intelligence test and a comprehensive questionnaire covering socio-demographic factors, lifestyle, and health-related factors. The data were collected in test sessions with up to 24 participants per session. Using the unique personal identification number assigned to all Danes, the cohort has been linked to data from national administrative and health registers for prospectively collected data on socioeconomic and health-related factors. UTILITY AND DISCUSSION The DanACo cohort has some major strengths compared to existing cognitive aging cohorts such as a large sample size (n = 5,183 men), a validated global measure of cognitive ability, a long retest interval (mean 44.0 years) and the availability of prospectively collected data from registries as well as comprehensive questionnaire data. The main weakness is the low participation rate (14.3%) and that the cohort consists of men only. CONCLUSION Cognitive decline is a result of a summary of factors across the life-course. The DanACo cohort is characterized by a long retest interval and contains data on a wealth of factors across adult life which is essential to establish evidence on predictors of cognitive decline. Moreover, the size of the cohort ensures sufficient statistical power to identify even relatively weak predictors of cognitive decline.
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Affiliation(s)
- Marie Grønkjær
- Center for Clinical Research and Prevention, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Nordre Fasanvej 57, 2000, Frederiksberg, Denmark
| | - Erik Lykke Mortensen
- Department of Public Health, Unit of Medical Psychology, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, 1353, Denmark
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Cathrine Lawaetz Wimmelmann
- Department of Public Health, Unit of Medical Psychology, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, 1353, Denmark
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
- Centre for Childhood Health, Islands Brygge 41, 2300, Copenhagen S, Denmark
| | - Trine Flensborg-Madsen
- Department of Public Health, Unit of Medical Psychology, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, 1353, Denmark
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Merete Osler
- Center for Clinical Research and Prevention, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Nordre Fasanvej 57, 2000, Frederiksberg, Denmark
- Department of Public Health, Section of Epidemiology, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, 1353, Denmark
| | - Gunhild Tidemann Okholm
- Center for Clinical Research and Prevention, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Nordre Fasanvej 57, 2000, Frederiksberg, Denmark.
- Department of Public Health, Unit of Medical Psychology, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, 1353, Denmark.
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark.
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Hegelund ER, Teasdale TW, Okholm GT, Osler M, Sørensen TIA, Christensen K, Mortensen EL. The secular trend of intelligence test scores: The Danish experience for young men born between 1940 and 2000. PLoS One 2021; 16:e0261117. [PMID: 34882746 PMCID: PMC8659667 DOI: 10.1371/journal.pone.0261117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/24/2021] [Indexed: 11/25/2022] Open
Abstract
The present study investigated the Danish secular trend of intelligence test scores among young men born between 1940 and 2000, as well as the possible associations of birth cohort changes in family size, nutrition, education, and intelligence test score variability with the increasing secular trend. The study population included all men born from 1940 to 2000 who appeared before a draft board before 2020 (N = 1,556,770). At the mandatory draft board examination, the approximately 19-year-old men underwent a medical examination and an intelligence test. In the statistical analyses, the IQ mean and standard deviation (SD) were estimated separately for each of the included annual birth cohorts based on information from birth cohorts with available total intelligence test scores for all tested individuals (i.e. 1940-1958 and 1987-2000; the mean and SD were interpolated for the intermediate birth cohorts). Moreover, the possible associations with birth cohort changes in family size, height as a proxy for nutritional status, education, and IQ variability were investigated among those birth cohorts for whom a secular increase in intelligence test scores was found. The results showed that the estimated mean IQ score increased from a baseline set to 100 (SD: 15) among individuals born in 1940 to 108.9 (SD: 12.2) among individuals born in 1980, since when it has decreased. Focusing on the birth cohorts of 1940-1980, for whom a secular increase in intelligence test scores was found, birth cohort changes in family size, height, and education explained large proportions of the birth cohort variance in mean intelligence test scores, suggesting that these factors may be important contributors to the observed Flynn effect in Denmark.
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Affiliation(s)
- Emilie R. Hegelund
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | | | - Gunhild T. Okholm
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospitals, Frederiksberg, Denmark
| | - Merete Osler
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospitals, Frederiksberg, Denmark
| | | | - Kaare Christensen
- Department of Public Health, University of Southern Denmark, Odense, Denmark
| | - Erik L. Mortensen
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
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