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Intelligence in youth and health behaviours in middle age

Intelligence in youth and health behaviours in middle age
Intelligence in youth and health behaviours in middle age

Objective: We investigated the association between intelligence in youth and a range of health-related behaviours in middle age. Method: Participants were the 5347 men and women who responded to the National Longitudinal Survey of Youth 1979 (NLSY-79) 2012 survey. IQ was recorded with the Armed Forces Qualification Test (AFQT) when participants were aged 15 to 23 years of age. Self-reports on exercise (moderate activity, vigorous activity, and strength training), dietary, smoking, drinking, and oral health behaviours were recorded when participants were in middle age (mean age = 51.7 years). A series of regression analyses tested for an association between IQ in youth and the different health related behaviours in middle age, while adjusting for childhood socio-economic status (SES) and adult SES. Results: Higher IQ in youth was significantly associated with the following behaviours that are beneficial to health: being more likely to be able to do moderate cardiovascular activity (Odds Ratio, 95% CI) (1.72, 1.35 to 2.20, p <.001) and strength training (1.61, 1.37 to 1.90, p <.001); being less likely to have had a sugary drink in the previous week (0.75, 0.71 to 0.80, p <.001); a lower likelihood of drinking alcohol heavily (0.67, 0.61 to 0.74, p <.001); being less likely to smoke (0.60, 0.56 to 0.65, p <.001); being more likely to floss (1.47, 1.35 to 1.59, p <.001); and being more likely to say they “often” read the nutritional information (1.20, 1.09 to 1.31, p <.001) and ingredients (1.24, 1.12 to 1.36, p <.001) on food packaging compared to always reading them. Higher IQ was also linked with dietary behaviours that may or may not be linked with poorer health outcomes (i.e. being more likely to have skipped a meal (1.10, 1.03 to 1.17, p =.005) and snacked between meals (1.37, 1.26 to 1.50, p <.001) in the previous week). An inverted u-shaped association was also found between IQ and the number of meals skipped per week. Higher IQ was also linked with behaviours that are known to be linked with poorer health (i.e. a higher likelihood of drinking alcohol compared to being abstinent from drinking alcohol (1.58, 1.47 to 1.69, p <.001)). A u-shaped association was found between IQ and the amount of alcohol consumed per week and an inverted u-shaped association was found between IQ and the number of cigarettes smoked a day. Across all outcomes, adjusting for childhood SES tended to attenuate the estimated effect size only slightly. Adjusting for adult SES led to more marked attenuation but statistical significance was maintained in most cases. Conclusion: In the present study, a higher IQ in adolescence was associated with a number of healthier behaviours in middle age. In contrast to these results, a few associations were also identified between higher intelligence and behaviours that may or may not be linked with poor health (i.e. skipping meals and snacking between meals) and with behaviours that are known to be linked with poor health (i.e. drinking alcohol and the number of cigarettes smoked). To explore mechanisms of association, future studies could test for a range of health behaviours as potential mediators between IQ and morbidity or mortality in later life.

0160-2896
71-86
Wraw, Christina
b9230287-fb59-4fe0-a135-de0619de45fb
Der, Geoff
e29a38e2-7d7d-4f7f-bc79-7f37745790d3
Gale, Catharine R.
5bb2abb3-7b53-42d6-8aa7-817e193140c8
Deary, Ian J.
027158ae-fbfb-40ea-98b1-32d2690499ac
Wraw, Christina
b9230287-fb59-4fe0-a135-de0619de45fb
Der, Geoff
e29a38e2-7d7d-4f7f-bc79-7f37745790d3
Gale, Catharine R.
5bb2abb3-7b53-42d6-8aa7-817e193140c8
Deary, Ian J.
027158ae-fbfb-40ea-98b1-32d2690499ac

Wraw, Christina, Der, Geoff, Gale, Catharine R. and Deary, Ian J. (2018) Intelligence in youth and health behaviours in middle age. Intelligence, 69, 71-86. (doi:10.1016/j.intell.2018.04.005).

Record type: Article

Abstract

Objective: We investigated the association between intelligence in youth and a range of health-related behaviours in middle age. Method: Participants were the 5347 men and women who responded to the National Longitudinal Survey of Youth 1979 (NLSY-79) 2012 survey. IQ was recorded with the Armed Forces Qualification Test (AFQT) when participants were aged 15 to 23 years of age. Self-reports on exercise (moderate activity, vigorous activity, and strength training), dietary, smoking, drinking, and oral health behaviours were recorded when participants were in middle age (mean age = 51.7 years). A series of regression analyses tested for an association between IQ in youth and the different health related behaviours in middle age, while adjusting for childhood socio-economic status (SES) and adult SES. Results: Higher IQ in youth was significantly associated with the following behaviours that are beneficial to health: being more likely to be able to do moderate cardiovascular activity (Odds Ratio, 95% CI) (1.72, 1.35 to 2.20, p <.001) and strength training (1.61, 1.37 to 1.90, p <.001); being less likely to have had a sugary drink in the previous week (0.75, 0.71 to 0.80, p <.001); a lower likelihood of drinking alcohol heavily (0.67, 0.61 to 0.74, p <.001); being less likely to smoke (0.60, 0.56 to 0.65, p <.001); being more likely to floss (1.47, 1.35 to 1.59, p <.001); and being more likely to say they “often” read the nutritional information (1.20, 1.09 to 1.31, p <.001) and ingredients (1.24, 1.12 to 1.36, p <.001) on food packaging compared to always reading them. Higher IQ was also linked with dietary behaviours that may or may not be linked with poorer health outcomes (i.e. being more likely to have skipped a meal (1.10, 1.03 to 1.17, p =.005) and snacked between meals (1.37, 1.26 to 1.50, p <.001) in the previous week). An inverted u-shaped association was also found between IQ and the number of meals skipped per week. Higher IQ was also linked with behaviours that are known to be linked with poorer health (i.e. a higher likelihood of drinking alcohol compared to being abstinent from drinking alcohol (1.58, 1.47 to 1.69, p <.001)). A u-shaped association was found between IQ and the amount of alcohol consumed per week and an inverted u-shaped association was found between IQ and the number of cigarettes smoked a day. Across all outcomes, adjusting for childhood SES tended to attenuate the estimated effect size only slightly. Adjusting for adult SES led to more marked attenuation but statistical significance was maintained in most cases. Conclusion: In the present study, a higher IQ in adolescence was associated with a number of healthier behaviours in middle age. In contrast to these results, a few associations were also identified between higher intelligence and behaviours that may or may not be linked with poor health (i.e. skipping meals and snacking between meals) and with behaviours that are known to be linked with poor health (i.e. drinking alcohol and the number of cigarettes smoked). To explore mechanisms of association, future studies could test for a range of health behaviours as potential mediators between IQ and morbidity or mortality in later life.

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Accepted/In Press date: 29 April 2018
e-pub ahead of print date: 24 May 2018
Published date: 1 July 2018

Identifiers

Local EPrints ID: 421371
URI: https://eprints.soton.ac.uk/id/eprint/421371
ISSN: 0160-2896
PURE UUID: 1d3b96b9-2819-4990-92fa-9e99d4fc094d
ORCID for Catharine R. Gale: ORCID iD orcid.org/0000-0002-3361-8638

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Date deposited: 06 Jun 2018 16:30
Last modified: 10 Dec 2019 01:54

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