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Sex Differences and Underlying Mechanisms

Catriona Syme, MSc; Michal Abrahamowicz, PhD; Gabriel T. Leonard, PhD; Michel Perron, PhD; Alain Pitiot, PhD; Xi Qiu, MSc; Louis Richer, PhD; John Totman, MSc; Suzanne Veillette, PhD; Yongling Xiao, MSc; Daniel Gaudet, MD, PhD; Tomas Paus, MD, PhD; Zdenka Pausova, MD

Arch Pediatr Adolesc Med. 2008;162(5):453-461.

Objective  To investigate the association between intra-abdominal adiposity and individual components of the metabolic syndrome (MS) in adolescent males and females.

Design  Cross-sectional study of a population-based cohort.

Setting  Saguenay Youth Study, Quebec, Canada.

Participants  A total of 324 adolescents, aged 12 to 18 years.

Intervention  Measures were compared between males and females with "high" or "low" intra-abdominal fat (IAF).

Main Outcome Measures  Intra-abdominal fat was quantified with magnetic resonance imaging. Primary outcome measures were blood pressure (BP) and fasting serum glucose, insulin, lipids, and C-reactive protein levels. Secondary mechanistic measures were cardiovascular variability indexes of autonomic nervous system function, pubertal development, and serum levels of cortisol, leptin, and sex hormones.

Results  The MS was completely absent in adolescents with low IAF and was present in 13.8% of males and 8.3% of females with high IAF. Excess IAF was associated with a higher homeostasis model assessment index (0.5 [95% confidence interval (CI), 0.3 to 0.8]; P < .001) and triglycerides level (17.7 mg/dL [to convert to millimoles per liter, multiply by 0.0113] [95% CI, 9.7 to 25.7 mg/dL]; P < .001), lower high-density lipoprotein cholesterol level (–3.9 mg/dL [to convert to millimoles per liter, multiply by 0.0259] [95% CI, –6.2 to –1.5 mg/dL]; P = .003), and higher C-reactive protein level (0.03 mg/L [to convert to nanomoles per liter, multiply by 9.524] [95% CI, 0.01 to 0.05 mg/L]; P = .003). High IAF was associated with elevations of BP and sympathetic activity in males only (higher systolic BP, 6 mm Hg [95% CI, 1 to 11 mm Hg]; P = .02 and low-frequency power of diastolic BP, 629 mm Hg² [95% CI, 37 to 1222 mm Hg²]; P = .04).

Conclusions  Our results suggest that, already in adolescence, accumulation of IAF may promote development of the MS, affecting the metabolic and inflammatory components similarly in both sexes but influencing BP adversely only in males. The latter may be attributed, in part, to the augmentation of sympathetic activity also seen only in males.

Author Affiliations: Brain and Body Centre, University of Nottingham, Nottingham, England (Ms Syme, Drs Pitiot, Paus, and Pausova, and Messrs Totman and Qiu); and Department of Epidemiology and Biostatistics, McGill University (Drs Abrahamowicz, Leonard, and Paus and Ms Xiao) and Research Centre–CHUM (Centre hospitalier de l'Université de Montréal) (Dr Pausova), Montreal; Groupe ÉCOBES (d'étude des conditions de vie et des besoins de la population) (Drs Perron and Veillette), Université de Québec (Dr Richer), and Community Genomic Centre, Université de Montréal, Chicoutimi Hospital (Dr Gaudet), Chicoutimi, Quebec, Canada.

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