Abstract P181: Circulating Second-messenger Glycerophosphocholines and Cardiovascular Risk Factors in a Population-based Sample of Adolescents

Circulating second-messenger glycerophosphocholines (smGPCs), including lysophosphatidylcholines and platelet-activating factors, are low-abundance plasma phospholipids that modulate atherosclerosis and inflammation and, in turn, the risk for cardiovascular disease (CVD). Although CVD is a slow-progressing disease culminating in middle-to-late adulthood, its initial stages may be seen already in adolescence. Here, we investigated whether circulating smGPCs are associated with classical CVD risk factors - excess body fat, elevated BP, insulin resistance and low-grade inflammation - during adolescence. We studied a population-based sample of 1029 adolescents (52% females, 12-18 years), as part of the Saguenay Youth Study. We used targeted serum lipidomics (LC-ESI-MS) to identify and quantify circulating smGPCs within the 440-640 Da range. In all participants, we also measured: (i) visceral fat with MRI and total body fat with bioimpedance; (ii) blood pressure (BP) beat-by-beat for five minutes under standard clinical conditions; and (iii and iv) fasting serum insulin (as an index of insulin resistance) and CRP (as an index of low-grade inflammation). We identified a total of 81 smGPCs that varied by the length and saturation of their fatty acyl residues and the type of linkage these residues are attached to the glycerol backbone. Over 30 of them were associated with multiple CVD risk factors (p<6x10 -4 ). Most of these associations were inverse and involved ‘medium’ mass smGPCs. Positive associations were also seen and these involved ‘low’ or ‘high’ mass smGPCs. Most strongly inversely associated smGPCs were: (i) PC(20:6/0:0) and PC(O-18:6/2:0), which were associated with total body fat (p<3x10 -14 ) and CRP (p<8x10 -36 ); and (ii) PC(16:0/2:0), which was associated with visceral fat (p=2x10 -18 ) and BP (p<1x10 -5 ). The most strongly positively associated smGPC was PC(14:1/0:0), which was associated with visceral fat (p=8x10 -8 ) and fasting insulin (p=2x10 -24 ). Thus, specific circulating smGPCs are strongly associated with multiple CVD risk factors in adolescence; some of these associations may be ‘protective’ whereas others ‘adverse’. Circulating smGPCs may serve as novel biomarkers of early risk for CVD.

Discovery of β-D-2'-deoxy-2'-α-fluoro-4'-α-cyano-5-aza-7,9-dideaza adenosine as a potent nucleoside inhibitor of respiratory syncytial virus with excellent selectivity over mitochondrial RNA and DNA polymerases

Novel 4'-substituted β-d-2'-deoxy-2'-α-fluoro (2'd2'F) nucleoside inhibitors of respiratory syncytial virus (RSV) are reported. The introduction of 4'-substitution onto 2'd2'F nucleoside analogs resulted in compounds demonstrating potent cell based RSV inhibition, improved inhibition of the RSV polymerase by the nucleoside triphosphate metabolites, and enhanced selectivity over incorporation by mitochondrial RNA and DNA polymerases. Selectivity over the mitochondrial polymerases was found to be extremely sensitive to the specific 4'-substitution and not readily predictable. Combining the most potent and selective 4'-groups from N-nucleoside analogs onto a 2'd2'F C-nucleoside analog resulted in the identification of β-D-2'-deoxy-2'-α-fluoro-4'-α-cyano-5-aza-7,9-dideaza adenosine as a promising nucleoside lead for RSV.

Development and aetiology of body dissatisfaction in adolescent boys and girls

This longitudinal study aims to describe the development of body dissatisfaction (BD), measured with the Contour Drawing Rating Scale, between the ages of 14 and 18, and to identify factors associated with BD at age 18, among 413 adolescents. Between the ages of 14 and 18, the proportion of girls wanting to be thinner increased, although it remained unchanged among boys. A ratio of 1:2 girls and 1:5 boys reported having seriously tried to lose weight. Factors associated with BD in girls at age 18 were (1) wanting to be thinner, (2) body mass index (BMI), (3) weight control behaviours and (4) negative comments about weight. Factors associated with BD in boys at age 18 were (1) wanting to be thinner or bigger, (2) BMI, (3) having experienced sexual intercourse and (4) negative comments about weight. The high prevalence of BD and weight-related concerns suggest a need for early interventions.

Discovery of an oral respiratory syncytial virus (RSV) fusion inhibitor (GS-5806) and clinical proof of concept in a human RSV challenge study

GS-5806 is a novel, orally bioavailable RSV fusion inhibitor discovered following a lead optimization campaign on a screening hit. The oral absorption properties were optimized by converting to the pyrazolo[1,5-a]-pyrimidine heterocycle, while potency, metabolic, and physicochemical properties were optimized by introducing the para-chloro and aminopyrrolidine groups. A mean EC50 = 0.43 nM was found toward a panel of 75 RSV A and B clinical isolates and dose-dependent antiviral efficacy in the cotton rat model of RSV infection. Oral bioavailability in preclinical species ranged from 46 to 100%, with evidence of efficient penetration into lung tissue. In healthy human volunteers experimentally infected with RSV, a potent antiviral effect was observed with a mean 4.2 log10 reduction in peak viral load and a significant reduction in disease severity compared to placebo. In conclusion, a potent, once daily, oral RSV fusion inhibitor with the potential to treat RSV infection in infants and adults is reported.

Prenatal exposure to cigarette smoke interacts with OPRM1 to modulate dietary preference for fat

BACKGROUND

Preference for fatty foods is a risk factor for obesity. It is a complex behaviour that involves the brain reward system and is regulated by genetic and environmental factors, such as the opioid receptor mu-1 gene (OPRM1) and prenatal exposure to maternal cigarette smoking (PEMCS). We examined whether OPRM1 and PEMCS interact in influencing fat intake and whether exposure-associated epigenetic modifications of OPRM1 may mediate this gene-environment interaction.

METHODS

We studied adolescents from a French Canadian genetic founder population, half of whom were exposed prenatally to maternal cigarette smoking. Fat intake was assessed with a 24-hour food recall in the form of a structured interview conducted by a trained nutritionist. The OPRM1 variant rs2281617 was genotyped for the whole sample with the Illumina Human610-Quad and HumanOmniExpress BeadChips. Methylation of blood DNA was assessed at 21 CpGs across OPRM1 in a subset of the sample using the Illumina HumanMethylation450 BeadChip.

RESULTS

We included 956 adolescents in our study. In the whole sample, OPRM1 (T carrier in rs2281617) was associated with lower fat intake (-1.6%, p = 0.017), and PEMCS was associated with higher fat intake (+1.6%, p = 0.005). OPRM1 and PEMCS interacted with each other (p = 0.003); the "protective" (fat intake-lowering) allele of OPRM1 was associated with lower fat intake in nonexposed (-3.2%, p < 0.001) but not in exposed individuals (+0.8%, p = 0.42). Further, PEMCS was associated with lower DNA methylation across multiple CpGs across OPRM1 in exposed versus nonexposed individuals (p = 0.031).

LIMITATIONS

A limitation of our study was its cross-sectional design.

CONCLUSION

Our study suggests that PEMCS may interact with OPRM1 in increasing fat preference. Silencing of the protective OPRM1 allele in exposed adolescents might be related to epigenetic modification of this gene.

Puberty and testosterone shape the corticospinal tract during male adolescence

Some of the known sex differences in white matter emerge during adolescence. Here, we replicate and extend our previous findings of sex differences in the structure of the corticospinal tract (Perrin et al. 2009; Hervé et al. 2009). In a large normative sample of adolescents, we observed age × sex interactions in the signal intensity of T1-weighted (T1W) images (n = 941) and in magnetization transfer ratio (MTR; n = 761); both features were inversely associated with age in males but not in females. Moreover, we hypothesized that the age-related differences in CST structure exhibited by males would be mediated by differences in puberty stage and levels of bioavailable testosterone. We confirmed this prediction using mediation analysis with bootstrapping. These findings suggest that sex differences in the CST structure observed during male adolescence may be due to multiple processes associated with puberty, including (but not limited to) the rising levels of testosterone.

Maternal cigarette smoking during pregnancy predicts drug use via externalizing behavior in two community-based samples of adolescents

BACKGROUND AND AIMS

Prenatal exposure to maternal cigarette smoking (PEMCS) is associated with a higher probability of substance use in adolescence. We explore if externalizing behavior mediates this relationship, while controlling for a number of potential covariates of this mediation process.

METHODS

We used data obtained in two geographically distinct community samples of adolescents. The first (cross-sectional) sample consisted of 996 adolescents (12-18 years of age) recruited from the Saguenay Youth Study (SYS) in Canada (47% with PEMCS). The second (longitudinal) sample consisted of 1141 adolescents (49% with PEMCS) from the Northern Finland Birth Cohort (NFBC1986). In both samples, externalizing behavior and substance use were assessed during adolescence. In the NFBC1986 cohort, externalizing behavior was also assessed in childhood.

RESULTS

In both populations, PEMCS is associated with a higher likelihood of adolescent drug experimentation. In the NFBC1986 cohort, exposed (versus non-exposed) adolescents experiment with an extra 1.27 [B = 0.24, 95% confidence intervals (CI) = 0.15, 0.33 P < 0.001] drugs. In the SYS cohort, a clear protective effect of not being exposed is shown: non-exposed (versus exposed) adolescents are 1.5 times [B = -0.42, 95% CI = -0.75, -0.09, P = 0.013] less likely to take drugs. These associations between PEMCS and drug experimentation remain in the multivariate and mediational analyses.

CONCLUSIONS

Prenatal exposure to maternal cigarette smoking appears to be associated with a higher probability of experimenting with drugs during adolescence, both directly and indirectly via externalizing behavior and the number of peers reported as using drugs.

Adiposity is associated with structural properties of the adolescent brain

Obesity, a major risk factor for cardiometabolic disease, is associated with variations in a number of structural properties in the adult brain, as assessed with magnetic resonance imaging (MRI). In this study, we investigated the cross-sectional relationship between visceral fat (VF), total body fat (TBF) and three MRI parameters in the brains of typically developing adolescents: (i) T1-weighted (T1W) signal intensity; (ii) T1W signal contrast between white matter (WM) and gray matter (GM); and (iii) magnetization transfer ratio (MTR). In a community-based sample of 970 adolescents (12-18 years old, 466 males), VF was quantified using MRI, and total body fat was measured using a multifrequency bioimpedance. T1W images of the brain were used to determine signal intensity in lobar GM and WM, as well as WM:GM signal contrast. A magnetization transfer (MT) sequence of MT(ON) and MT(OFF) was used to obtain MTR in GM and WM. We found that both larger volumes of VF and more TBF were independently associated with higher signal intensity in WM and higher WM:GM signal contrast, as well as higher MTR in both GM and WM. These relationships were independent of a number of potential confounders, including age, sex, puberty stage, household income and height. Our results suggest that both visceral fat and fat deposited elsewhere in the body are associated independently with structural properties of the adolescent brain. We speculate that these relationships suggest the presence of adiposity-related variations in phospholipid composition of brain lipids.

Clustering of the metabolic syndrome components in adolescence: role of visceral fat

Visceral fat (VF) promotes the development of metabolic syndrome (MetS), which emerges as early as in adolescence. The clustering of MetS components suggests shared etiologies, but these are largely unknown and may vary between males and females. Here, we investigated the latent structure of pre-clinical MetS in a community-based sample of 286 male and 312 female adolescents, assessing their abdominal adiposity (VF) directly with magnetic resonance imaging. Principal component analysis of the five MetS-defining variables (VF, blood pressure [BP], fasting serum triglycerides, HDL-cholesterol and glucose) identified two independent components in both males and females. The first component was sex-similar; it explained >30% of variance and was loaded by all but BP variables. The second component explained >20% of variance; it was loaded by BP similarly in both sexes but additional loading by metabolic variables was sex-specific. This sex-specificity was not detected in analyses that used waist circumference instead of VF. In adolescence, MetS-defining variables cluster into at least two sub-syndromes: (1) sex-similar metabolic abnormalities of obesity-induced insulin resistance and (2) sex-specific metabolic abnormalities associated with BP elevation. These results suggest that the etiology of MetS may involve more than one pathway and that some of the pathways may differ between males and females. Further, the sex-specific metabolic abnormalities associated with BP elevation suggest the need for sex-specific prevention and treatment strategies of MetS.

Height-based Indices of Pubertal Timing in Male Adolescents

It is important to account for timing of puberty when studying the adolescent brain and cognition. The use of classical methods for assessing pubertal status may not be feasible in some studies, especially in male adolescents. Using data from a sample of 478 males from a longitudinal birth cohort, we describe the calculations of three independent height-based markers of pubertal timing: Age at Peak Height Velocity (APHV), Height Difference in Standard Deviations (HDSDS), and Percent Achieved of Adult Stature (PAAS). These markers correlate well with each other. In a separate cross-sectional study, we show that the PAAS marker correlates well with testosterone levels and self-reported pubertal-stage scores. We conclude by discussing key considerations for investigators when drawing upon these methods of assessing pubertal timing.

Prenatal exposure to maternal cigarette smoking, amygdala volume, and fat intake in adolescence

CONTEXT

Prenatal exposure to maternal cigarette smoking is a well-established risk factor for obesity, but the underlying mechanisms are not known. Preference for fatty foods, regulated in part by the brain reward system, may contribute to the development of obesity.

OBJECTIVE

To examine whether prenatal exposure to maternal cigarette smoking is associated with enhanced fat intake and risk for obesity, and whether these associations may be related to subtle structural variations in brain regions involved in reward processing.

DESIGN

Cross-sectional study of a population-based cohort.

SETTING

The Saguenay Youth Study, Quebec, Canada.

PARTICIPANTS

A total of 378 adolescents (aged 13 to 19 years; Tanner stage 4 and 5 of sexual maturation), half of whom were exposed prenatally to maternal cigarette smoking (mean [SD], 11.1 [6.8] cigarettes/d).

MAIN OUTCOME MEASURES

Fat intake was assessed with a 24-hour food recall (percentage of energy intake consumed as fat). Body adiposity was measured with anthropometry and multifrequency bioimpedance. Volumes of key brain structures involved in reward processing, namely the amygdala, nucleus accumbens, and orbitofrontal cortex, were measured with magnetic resonance imaging.

RESULTS

Exposed vs nonexposed subjects exhibited a higher total body fat (by approximately 1.7 kg; P = .009) and fat intake (by 2.7%; P = .001). They also exhibited a lower volume of the amygdala (by 95 mm3; P < .001) but not of the other 2 brain structures. Consistent with its possible role in limiting fat intake, amygdala volume correlated inversely with fat intake (r = -0.15; P = .006).

CONCLUSIONS

Prenatal exposure to maternal cigarette smoking may promote obesity by enhancing dietary preference for fat, and this effect may be mediated in part through subtle structural variations in the amygdala.

FTO, obesity and the adolescent brain

Genetic variations in fat mass- and obesity (FTO)-associated gene, a well-replicated gene locus of obesity, appear to be associated also with reduced regional brain volumes in elderly. Here, we examined whether FTO is associated with total brain volume in adolescence, thus exploring possible developmental effects of FTO. We studied a population-based sample of 598 adolescents recruited from the French Canadian founder population in whom we measured brain volume by magnetic resonance imaging. Total fat mass was assessed with bioimpedance and body mass index was determined with anthropometry. Genotype-phenotype associations were tested with Merlin under an additive model. We found that the G allele of FTO (rs9930333) was associated with higher total body fat [TBF (P = 0.002) and lower brain volume (P = 0.005)]. The same allele was also associated with higher lean body mass (P = 0.03) and no difference in height (P = 0.99). Principal component analysis identified a shared inverse variance between the brain volume and TBF, which was associated with FTO at P = 5.5 × 10(-6). These results were replicated in two independent samples of 413 and 718 adolescents, and in a meta-analysis of all three samples (n = 1729 adolescents), FTO was associated with this shared inverse variance at P = 1.3 × 10(-9). Co-expression networks analysis supported the possibility that the underlying FTO effects may occur during embryogenesis. In conclusion, FTO is associated with shared inverse variance between body adiposity and brain volume, suggesting that this gene may exert inverse effects on adipose and brain tissues. Given the completion of the overall brain growth in early childhood, these effects may have their origins during early development.

Abstract 157: The Sex-Specific Influence of Adiposity on Blood Pressure During Physical and Mental Challenges in Adolescence

Greater blood pressure (BP) reactivity and slower BP recovery from physical and mental challenges predict future hypertension. Males exhibit higher BP than females throughout their reproductive age and, as such, have a higher prevalence of hypertension. Excess body-fat is a major risk factor for hypertension in both males and females. We investigated whether BP reactivity and recovery from physical and mental challenges differ between adolescent males and females, and whether these hemodynamic parameters are associated with resting BP and are influenced by excess body-fat in a sex-specific manner. In 285 male and 311 female adolescents (age 12-18 years), we quantified visceral fat (VF) with magnetic resonance imaging and total body fat (TBF) with bioimpedance and measured systolic BP (SBP) beat-by-beat at rest and during physical (10-min standing) and mental (2-min math test) challenges. Our results showed that in both sexes, BP reactivity and BP recovery for both challenges (adjusted for age, height and initial BP) correlated closely with resting BP (0.03 ≤ r2 ≤ 0.34). In addition, for both physical and mental challenges, males versus females showed greater BP reactivity (by 3.5 mm Hg, p<0.0001 and by 2.6 mmHg, p=0.02, respectively) and no difference in BP recovery. VF correlated positively with BP reactivity to the physical challenge only and in males only (r=0.18, p=0.007), and this correlation was independent of TBF (r=0.21, p=0.002). Consistent with these results, additional adjustment for VF diminished the sex difference in BP reactivity to the physical but not mental challenge (from 3.5 to 2.7 mm Hg, p=0.01). No relationship was observed between VF and BP recovery from either challenge and in either sex. This is the first study to show sex differences exist not only in BP adaptation to daily activities, but also in the way VF influences this adaptation. Overall, our findings suggest the need for sex-specific prevention and treatment of hypertension.

Abstract 164: CYP17A1 Variant is Associated with Blood Pressure Reactivity to a Mental but not a Physical Challenge in Male Adolescents and May Be an Early Marker of Hypertension Risk

Individuals who exhibit exaggerated blood pressure (BP) reactivity to physical and mental challenges at a young age are at increased risk of developing hypertension in adulthood. Hypertension is a complex genetic trait that is more prevalent in men than women during reproductive age. CYP17A1 is one of the best-established gene loci of hypertension. It encodes a key enzyme in the steroidogenic pathway that produces mineralocorticoids, glucocorticoids, androgens, and estrogens; as such, it may influence BP reactivity in a sex-specific manner. Here, we investigated whether CYP17A1 is associated with BP reactivity to physical and mental challenges in adolescence. In 285 male and 311 female adolescents (age 12-18 years), we measured systolic BP (SBP) and diastolic BP (DBP) beat-by-beat during a 52-minute protocol, which included a physical (10-min standing) and mental (2-min math test) challenge and we genotyped 8 tagging single nucleotide polymorphisms (SNPs) that covered the entire region of CYP17A1. Genotype-phenotype association tests were performed separately in males and females, while adjusting for age, height and initial BP. Our results showed that 6 SNPs were associated with higher SBP and DBP reactivity (p=0.003-0.0001), but only in response to mental stress and only in boys. At rs619824 , minor allele homozygotes differed from major allele homozygotes by 8.7 mm Hg of SBP (p=3x10-4) and 4.8 mm Hg of DBP (p=1x10-4) in boys, and the two groups varied only by 2.0 mm Hg of SBP (p=0.31) and 0.9 mm Hg of DBP (p=0.42) in girls. These results suggest that CYP17A1 may contribute to the development of hypertension through the regulation of the stress response and that, at least in adolescence, this effect appears to be present in males but not in females.

Sex differences in the contributions of visceral and total body fat to blood pressure in adolescence

Excess body fat deposited viscerally rather than elsewhere in the body is associated with higher risk for hypertension; this relationship is stronger in men than in women. Here we investigated whether similar sex dimorphism exists already in adolescence. A population-based sample of adolescent boys (n=237) and girls (n=262), age 12 to 18 years, was studied. Total body fat (TBF) was assessed with multifrequency bioelectrical impedance, and visceral fat (VF) was quantified with MRI. Blood pressure (BP) was measured beat by beat during an hour-long protocol, including supine, standing, sitting, mental stress, and poststress sections. Multivariate mixed-model analysis was used to assess the relative contributions of TBF and VF to BP during these sections. In boys, BP was strongly positively associated with VF (P<0.0001), whereas it was less strongly and negatively associated with TBF (P=0.004); these relationships did not substantially vary during the protocol. In contrast, in girls, BP was strongly positively associated with TBF (P=0.0006), whereas it was not associated with VF (P=0.08); the relationship with TBF varied during the protocol and was most apparent during mental stress (TBF*section interaction: P=0.002). Furthermore, when waist circumference was included in multivariate models instead of VF, it was not associated with BP in either sex; this indicates that waist circumference may not be an appropriate surrogate for VF. Thus, in adolescence, adiposity-related BP elevation is driven mainly by visceral fat in males and by fat deposited elsewhere in females. This dimorphism suggests sex-specific mechanisms of obesity-induced hypertension and the need for sex-specific criteria of its prevention.

Genome-wide scan for loci of adolescent obesity and their relationship with blood pressure

CONTEXT

Hypertension, typically considered a disorder of adulthood, is now emerging in adolescence. This is mainly due to the growing prevalence of obesity and the fact that excess body fat increases blood pressure (BP).

OBJECTIVE

The objective of the study was to investigate whether genome-wide identified gene loci of obesity are associated with elevated BP in adolescence.

DESIGN

This was a genotype-phenotype association study.

SETTING

The study was conducted in a French-Canadian founder population.

PARTICIPANTS

Participants included 598 adolescents, aged 12-18 yr.

INTERVENTION

Testing associations between 530,011 single-nucleotide polymorphisms (SNP; Human610W-Quad BeadChip) and obesity measures and between identified SNP and BP.

PRIMARY OUTCOME MEASURES

Total fat mass (TFM) was assessed with bioelectrical impedance, and body mass index (BMI) was determined with anthropometry. BP was measured beat by beat during an hour-long protocol.

RESULTS

The genome-wide association studies of TFM and BMI revealed two novel and several previously identified loci of obesity. The former were PAX5 (rs16933812, TFM: P = 9.3 × 10(-9)) and MRPS22 (rs7638110, BMI: P = 4.6 × 10(-8)), and the top ones among the latter (P < 5 × 10(-4)) were MC4R (rs17773430, BMI: P = 5.8 × 10(-6)), FTO (rs9930333, BMI: P = 1.9 × 10(-4)), and MTCH2 (rs7120548, BMI: P = 1.9 × 10(-4)). From these five, only the PAX5, MRPS22, and FTO were also associated with BP; their minor allele homozygotes vs. major allele homozygotes showed greater TFM by 2.9-8.0 kg and higher BP by 3.3-6.7 mm Hg.

CONCLUSIONS

Genome-wide association studies conducted in an adolescent founder population revealed two new and a number of previously identified loci of obesity and demonstrated that several but not all of these loci are also associated with elevated BP. These results begin to reveal the genetic architecture of obesity-induced hypertension.

KCTD8 gene and brain growth in adverse intrauterine environment: a genome-wide association study

The most dramatic growth of the human brain occurs in utero and during the first 2 years of postnatal life. Genesis of the cerebral cortex involves cell proliferation, migration, and apoptosis, all of which may be influenced by prenatal environment. Here, we show that variation in KCTD8 (potassium channel tetramerization domain 8) is associated with brain size in female adolescents (rs716890, P = 5.40 × 10(-09)). Furthermore, we found that the KCTD8 locus interacts with prenatal exposure to maternal cigarette smoking vis-à-vis cortical area and cortical folding: In exposed girls only, the KCTD8 locus explains up to 21% of variance. Using head circumference as a proxy of brain size at 7 years of age, we have replicated this gene-environment interaction in an independent sample. We speculate that KCTD8 might modulate adverse effects of smoking during pregnancy on brain development via apoptosis triggered by low intracellular levels of potassium, possibly reducing the number of progenitor cells.

Testosterone-mediated sex differences in the face shape during adolescence: subjective impressions and objective features

Sex identification of a face is essential for social cognition. Still, perceptual cues indicating the sex of a face, and mechanisms underlying their development, remain poorly understood. Previously, our group described objective age- and sex-related differences in faces of healthy male and female adolescents (12-18 years of age), as derived from magnetic resonance images (MRIs) of the adolescents' heads. In this study, we presented these adolescent faces to 60 female raters to determine which facial features most reliably predicted subjective sex identification. Identification accuracy correlated highly with specific MRI-derived facial features (e.g. broader forehead, chin, jaw, and nose). Facial features that most reliably cued male identity were associated with plasma levels of testosterone (above and beyond age). Perceptible sex differences in face shape are thus associated with specific facial features whose emergence may be, in part, driven by testosterone.

Risk factors for work-related fatigue in students with school-year employment

PURPOSE

To explore potential risk factors for acute and chronic work-related fatigue in students working at a paid job while pursuing school studies. Although work-related fatigue was identified as a potential hazard for youth health, academic achievement, and occupational safety, very few studies have specifically addressed its correlates and possible predictors.

METHODS

Cross-sectional data from an ongoing prospective cohort study of health risk behaviors in adolescents was used to identify factors associated with increased levels of acute and chronic fatigue in 209 students aged 17-18 years working during the school year. Multiple stepwise regression analyses were performed with acute and chronic fatigue levels as dependent variables, and demographic, work, and health factors as potential explanatory variables.

RESULTS

Average hours worked per week by students was 14.7 hours. It was observed that higher psychological distress, poorer health perception, greater sleep debt, and higher exposure to physical work factors were associated with higher levels of acute fatigue. Also, it was observed that higher psychological distress, poorer health perception, higher exposure to physical work factors, and holding multiple jobs were associated with higher levels of chronic fatigue. The number of hours worked weekly was associated with neither acute nor chronic work-related fatigue.

CONCLUSIONS

Findings suggest that prevention strategies devised to minimize work-related fatigue in students should consider exposure to physical work factors. Results also re-emphasize the importance of obtaining sufficient sleep so as to prevent high levels of acute work-related fatigue.