Explain Sex Differences Research Articles

Pubertal development, physical activity, and sedentary behavior among South Korean adolescents

Background: Sex differences in physical activity (PA) and sedentary behavior (SB) are well-established. However, recent research suggested that variations in pubertal development may explain sex differences in PA and SB among adolescents. Objective: This study examined whether pubertal development mediates the relationship between sex and PA, and SB respectively. Methods: The 2012 Korea Youth Risk Behavior Web-based Survey included data from 74,186 students in grades 7 to 12 (mean age = 14.94 ± 1.8; 48.5% girls). Pubertal development was indicated by the year in which the student reported they had experienced menarche for girls and semenarche for boys. Testing for mediation involved a bootstrapping resampling approach with self-reported PA and SB as criterion variables and taking into account covariates (chronological age, body mass index, school type, household income, and parental education). Results: Boys engaged in PA more frequently (3.30 ± 2.1 vs. 2.29 ± 1.7 day/week) and spent less time in SB (2.75 ± 1.2 vs. 2.93 ± 1.2 hr/day) than girls. Direct effects were found between sex and PA (β = -0.58 ± .01; p < .05), and sex and SB (β = 0.17 ± 0.01; p < .05). Pubertal development did not significantly mediate the relationship between sex and PA (β = 0.00; bias-corrected 95% confidence interval [BC 95% CI] [-0.01, 0.01]). Though pubertal development significantly mediated the association between sex and SB, the effect was small (β = 0.01; BC 95% CI [0.00, 0.02]). Conclusions: Sex appears to be an important predictor of PA and SB. Nonetheless, it is most likely that a combination of individual (e.g., psychological, biological) and sociocultural factors contribute to adolescents' movement behavior.

Sexual Dimorphism in Bones of the Thenar and Hypothenar Aspects of the Hand

Osteoarthritis of the pollical carpometacarpal joint is significantly more prevalent in females than in males. Although a number of hypotheses to explain sex differences in the prevalence of thumb osteoarthritis have been proposed, one possibility is that it is a product of sexual dimorphism where female hands have smaller joint surfaces relative to muscle strength, which results in higher stresses on the joints. Although dimorphism of the skull and long bones has been extensively researched, there are few basic data on female‐versus‐male differences in the short and irregular bones. Therefore, it is unclear whether sexual dimorphism is a relevant avenue of investigation for determining the cause of such sex‐based differences in hand pathology. Because powerful precision gripping is dependent on the thenar and hypothenar muscles, the hand bones with muscle attachments or that are directly subjected to transarticular loading by these muscles are of particular interest. Therefore, we investigated four hand bones contributing to the first and fifth carpometacarpal articulations in a sample of humans of African and European descent, and it was predicted that females would have smaller overall bone volumes and areas, smaller individual joint surface areas, as well as different joint and muscle attachment shapes. The hamate, trapezium, first metacarpal (Mc1), and fifth metacarpal (Mc5) of each individual were laser scanned to generate 3D surface polygon models. Volume and surface area were calculated for each bone as a whole in addition to the areas of specific joint surfaces. The shape of the pollical carpometacarpal joint (proximal Mc1 and distal trapezium) was assessed with quadric fitting functions to determine their dorsovolar and radioulnar curvatures. For the hamate, the orientation of the triquetrohamate joint surface relative to the proximodistal axis was quantified, and for the hamulus (which provides attachments for the flexor digiti minimi brevis, opponens digiti minimi, and flexor carpi ulnaris) its length, width, breadth, and angle were measured. The results indicate that females tend to have bones that are significantly smaller in overall size with correspondingly smaller joint surfaces, and a hamulus that differs in both size and shape. Future work will diversify the sample and incorporate measurements of relative thenar and hypothenar muscle force potential to further evaluate the biomechanical consequences of skeletal dimorphism. Such an approach may allow us to better investigate more specific factors contributing to the increased osteoarthritis risk in the hands of females.Support or Funding InformationNational Science Foundation (BCS‐1539741, BCS‐1317047), Wenner‐Gren Foundation, Leakey Foundation

Variations in body morphology explain sex differences in thermoeffector function during compensable heat stress.

What is the central question of this study? Can sex-related differences in cutaneous vascular and sudomotor responses be explained primarily by variations in the ratio between body surface area and mass during compensable exercise that elicits equivalent heat-loss requirements and mean body temperature changes across participants? What is the main finding and its importance? Mass-specific surface area was a significant determinant of vasomotor and sudomotor responses in men and women, explaining 10-48% of the individual thermoeffector variance. Nonetheless, after accounting for changes in mean body temperature and morphological differences, sex explained only 5% of that inter-individual variability. It was concluded that sex differences in thermoeffector function are morphologically dependent, but not sex dependent. Sex is sometimes thought to be an independent modulator of cutaneous vasomotor and sudomotor function during heat exposure. Nevertheless, it was hypothesized that, when assessed during compensable exercise that evoked equal heat-loss requirements across participants, sex differences in those thermoeffectors would be explained by variations in the ratio between body surface area and mass (specific surface area). To evaluate that possibility, vasomotor and sudomotor functions were assessed in 60 individuals (36 men and 24 women) with widely varying (overlapping) specific surface areas (range, 232.3-292.7 and 241.2-303.1cm2 kg-1 , respectively). Subjects completed two trials in compensable conditions (28°C, 36% relative humidity) involving rest (20min) and steady-state cycling (45min) at fixed, area-specific metabolic heat-production rates (light, ∼135Wm-2 ; moderate, ∼200Wm-2 ). Equivalent heat-loss requirements and mean body temperature changes were evoked across participants. Forearm blood flow and vascular conductance were positively related to specific surface area during light work in men (r=0.67 and r=0.66, respectively; both P<0.05) and during both exercise intensities in women (light, r=0.57 and r=0.69; and moderate, r=0.64 and r=0.68; all P<0.05). Whole-body and local sweat rates were negatively related to that ratio (correlation coefficient range, -0.33 to -0.62; all P<0.05) during both work rates in men and women. Those relationships accounted for 10-48% of inter-individual thermoeffector variance (P<0.05). Furthermore, after accounting for morphological differences, sex explained no more than 5% of that variability (P<0.05). It was concluded that, when assessed during compensable exercise, sex differences in thermoeffector function were largely determined morphologically, rather than being sex dependent.

Reflexive characteristic adaptations explain sex differences in the Big Five: But not in neuroticism

To date, sex differences in the Big Five personality traits have been thoroughly studied and well-documented. In the present two studies I examined if individual's opinions and interpretations of personality traits (reflexive characteristic adaptations, RCA) can eliminate these differences. Three RCA—attitudes toward traits, meta-traits, and meta-attitudes toward traits—were investigated. When measuring meta-traits and meta-attitudes toward traits, the images of students' parents (Study 1) and their best friends (Study 2) were employed as significant others. Study 1 (N=1030) revealed that women scored higher than men in neuroticism, extraversion, agreeableness, and openness. However, RCA eliminated these effects, with the exception of neuroticism. These results were largely replicated in Study 2 (N=333). Women scored higher than men in neuroticism and agreeableness. Again, these differences were eliminated by RCA, although the difference in neuroticism approached statistical significance. This research demonstrates that RCA may explain sex differences in various personality traits. Neuroticism may constitute a special case where men and women still differ in a trait beyond the contribution of RCA. The present study demonstrates that sex differences in the remaining traits may result from one's interpretations and opinions of these traits rather than from the traits themselves.

Thoracic Aortic Aneurysm Growth: Role of Sex and Aneurysm Etiology.

BackgroundThoracic aortic aneurysm (TAA) outcomes are worse in women than men, although reasons for sex differences are unknown. Because faster TAA growth is a risk factor for acute aortic syndromes, we sought to determine the role of sex and aneurysm etiology on TAA growth.Methods and ResultsEighty‐two consecutive unoperated subjects with TAA who had serial aneurysm measurements were recruited. In multivariable linear regression the association of female sex with aneurysm growth rate was assessed after adjustment for potential confounders. We also tested the interaction term sex×aneurysm etiology in the prediction of TAA growth. Seventy‐four percent of subjects were men; mean±SD age was 62.4±11.9 years in men and 67.7±10.7 years in women (P=0.06). Forty‐seven (57%) subjects had degenerative TAAs, and the remainder had heritable TAAs. Absolute baseline aneurysm size and follow‐up time were not different between men and women. Aneurysm growth rate was 1.19±1.15 mm/y in women and 0.59±0.66 mm/y in men (P=0.02). Female sex remained significantly associated with greater aneurysm growth in multivariable analyses (β±SE: 0.35±0.12, P=0.005). In addition, female sex was associated with faster TAA growth only among those with degenerative TAA (β±SE: 0.33±0.08, P=0.0002) and not among those with heritable TAA (P=0.79), with a significant sex×etiology interaction (P=0.001).Conclusions TAA growth rates are greater in women than men, and this difference is specific to women with degenerative TAAs. Our findings may explain sex differences in TAA outcomes and provide a foundation for future investigations of this topic.

Abstract TP179: Sex Differences in Stroke Risk Factors and Severity at Presentation

Introduction: While men suffer from more strokes in younger and middle age, the incidence of stroke is higher among women in older age. Specifically, 60% of stroke fatalities occur in females and 40% occur in males. Recent findings have attributed these sex-specific differences to a surge in the prevalence of cardiovascular risk factors among women. Traditionally, men have presented more frequently with micro-vascular complications (hypertension, diabetes, hyperlipidemia, and obesity), but now these risks are increasing in women. Hypothesis: Whether the modifiable risk factors examined, both alone and together, will differ in their ability to predict stroke severity across sex. Methods: A retrospective analysis of 811 primary stroke cases from two comprehensive and two primary stroke centers in a single region were analyzed for prevalence of modifiable and non-modifiable risk factors. Risk factors such as medical comorbidities, clinical findings and behavioral risk factors were compared across sexes and then assessed for correlation with initial presentation severity and ambulatory status. The relative influence of risk factors on sex differences in stroke severity (NIH Stroke Scale) and symptomatology were tested. Results: Females were more likely to present as non-Hispanic, with history of migraines and more severe levels of hypertension, with hypertensive crisis status at presentation relative to normal hypertensive state (all p &lt; 0.05). Males were more likely to present with history of coronary artery disease, documentation of drug or alcohol use, higher fasting blood sugar, A1c, and BMI levels at presentation (all p &lt; 0.05). Multivariate models improved the observed association between female sex and severe NIHSS score (OR = 2.1 [1.03-4.35]) through inclusion of hypertension, fasting blood sugar, and diabetes status. Conclusions: While the sex differences in strokes are well studied, the complex interrelationships between sex, variance in known medical risk factors, and severity of stroke presentation are not so well understood. This study identifies new patterns in risk by building independent models for odds of stroke severity for each sex, which may in turn help to explain sex differences in stroke presentation phenotype.

The Male Brain, Testosterone and Sex Differences in Professional Achievement

Lynn argues that sex differences in intelligence and drive (underpinned by testosterone) help to explain sex differences in high achievement. This comment proposes that this view can be developed by looking at Baron-Cohen’s concept of the ‘male brain’, which in its extreme manifestations presents as autism-spectrum disorders. It shows that this personality type — specifically a moderately strongly male brain combined with the outlier high IQ also more common among men — is associated with genius, and so the highest levels of achievement, and is partly a reflection of elevated testosterone. Thus an optimally high level of testosterone, also associated with faster life history strategy, is behind both elevated male drive and a greater ability to innovate, systematize and make important breakthroughs, leading to the highest levels of professional achievement. The comment shows that the ‘male brain’ is independent of intelligence and that even the highest echelons of the ‘oldest profession’ are male dominated, as the male brain model would predict.

Sexual Regret.

The current study sought to answer three key questions about explaining the emotion of regret in the domain of casual sex: Are sex differences in sexual regret robust or attenuated in a highly egalitarian culture? What proximate psychological variables might explain sex differences in sexual regret? And what accounts for within-sex variation in experiences of sexual regret about casual sex. We conducted a study of 263 Norwegian students (ages 19-37) who reported how much they regretted having either engaged in, or passed up, their most recent casual sexual experience. Sex differences in sexual regret are not attenuated in this sexually egalitarian culture. The study revealed sex differences in worries about pregnancy, STIs, and reputation; however, these predictors did not succeed in accounting for the sex differences in regret engaging in casual sex. Sexual gratification and socio-sexual orientation both predicted the sex differences in casual sex regret. In contrast, only socio-sexual orientation attenuated the sex difference in regret passing up casual sex. Predictors of within-sex variation in casual sexual regret included worry about sexual reputation, experienced gratification during the encounter, and socio-sexual orientation. Discussion focuses on implications for the psychological design features of this relatively neglected emotion.

Recursive Associations Among Maladaptive Cognitions and Symptoms of Social Anxiety and Depression: Implications for Sex Differences

Recent theories suggest that relationships between cognitive factors and symptoms of anxiety and depression are reciprocal and recursive. The first aim of this study was to evaluate the recursive relationships among two types of maladaptive cognitions (negative automatic thoughts and social looming cognitive style) and symptoms of social anxiety and depression. The second aim of the study was to test whether these reciprocal relationships help to explain sex differences in emotional problems and maladaptive cognitions. A total of 640 adolescents and young adults (52.65% women) participated in this study and filled in questionnaires at two waves, spaced 6 months apart. Participants were between 16 and 25 years old (Mage = 18.27, SDage = 2.21). The path analyses indicated that social looming at T1 predicted social anxiety at T2 and negative self-concept thoughts at T1 predicted social anxiety and depressive symptoms at T2. In addition, social anxiety at T1 predicted social looming at T2 and social anxiety a...

Sex Differences in Gray Matter Volume of the Right Anterior Hippocampus Explain Sex Differences in Three-Dimensional Mental Rotation.

Behavioral studies have reported that males perform better than females in 3-dimensional (3D) mental rotation. Given the important role of the hippocampus in spatial processing, the present study investigated whether structural differences in the hippocampus could explain the sex difference in 3D mental rotation. Results showed that after controlling for brain size, males had a larger anterior hippocampus, whereas females had a larger posterior hippocampus. Gray matter volume (GMV) of the right anterior hippocampus was significantly correlated with 3D mental rotation score. After controlling GMV of the right anterior hippocampus, sex difference in 3D mental rotation was no longer significant. These results suggest that the structural difference between males’ and females’ right anterior hippocampus was a neurobiological substrate for the sex difference in 3D mental rotation.

Do sex differences in rumination explain sex differences in depression?

It is generally accepted that women tend to ruminate more than men do and these thought patterns are often associated with depressive symptoms (Nolen-Hoeksema et al., ). Based on these findings, we considered whether the relationship between rumination and depression is stronger in women than in men and if so, whether this might explain the higher prevalence of major depressive disorder (MDD) in women and finally, whether the association can be disrupted through a mind/body intervention. Adult men and women, most of whom were clinically depressed, participated in an intervention known as MAP Training, which combines "mental" training with silent meditation and "physical" training with aerobic exercise (Shors et al., ). After eight weeks of training, both men and women reported significantly fewer symptoms of depression and fewer ruminative thoughts (Alderman et al., ). Statistical correlations between depressive symptoms and ruminative thoughts were strong and significant (rho > 0.50; p < 0.05) for both men and women before and after MAP Training. However, only in women did depressive symptoms relate to "reflective" ruminations, which involve analyses of past events, feelings, and behaviors. This is also the only relationship that dissipated after the intervention. In general, these analyses suggest that the strength of the relationship between depressive symptoms and rumination does not necessarily explain sex differences in depression; but because the relationship is strong, targeting rumination through intervention can reduce the incidence of MDD, which is more prevalent among women. © 2016 Wiley Periodicals, Inc.

Sex differences in neuroimmunity and pain.

Differences in the prevalence of chronic pain in women vs. men are well known, and decades of laboratory experimentation have demonstrated that women are more sensitive to pain than are men. Attention has thus shifted to investigating mechanisms underlying such differences. Recent evidence suggests that neuroimmune modulation of pain may represent an important cause of sex differences. The current Review examines the evidence for gonadal hormone modulation of the immune system, immune system modulation of pain, and interactions that might help to explain sex differences in pain. © 2016 Wiley Periodicals, Inc.

Does induced masseter muscle pain affect integrated jaw-neck movements similarly in men and women?

Normal jaw opening-closing involves simultaneous jaw and head-neck movements. We previously showed that, in men, integrated jaw-neck movements during jaw function are altered by induced masseter muscle pain. The aim of this study was to investigate possible sex-related differences in integrated jaw-neck movements following experimental masseter muscle pain. We evaluated head-neck and jaw movements in 22 healthy women and 16 healthy men in a jaw opening-closing task. The participants performed one control trial and one trial with masseter muscle pain induced by injection of hypertonic saline. Jaw and head movements were registered using a three-dimensional optoelectronic recording system. There were no significant sex-related differences in jaw and head movement amplitudes. Head movement amplitudes were significantly greater in the pain trials for both men and women. The proportional involvement of the neck motor system during jaw movements increased in pain trials for 13 of 16 men and for 18 of 22 women. Thus, acute pain may alter integrated jaw-neck movements, although, given the similarities between men and women, this interaction between acute pain and motor behaviour does not explain sex differences in musculoskeletal pain in the jaw and neck regions.

The role of attentional resources in explaining sex differences in object location memory.

Sex differences in object location memory have been widely studied, with mixed results. The role of attention in mediating the female advantage in object location memory has not been clearly understood yet. Two experiments, involving 181 participants and using an actual object array, were conducted in the present study to examine two learning conditions: incidental and intentional. In each experiment, participants were randomly assigned to divided versus full attention conditions. The study also examined memorizing location-maintained and location-exchanged objects. In both experiments, in both incidental and intentional learning conditions, women outperformed men in memorizing location-exchanged objects in the full but not in the divided attention condition. These findings confirm and extend previous ones concerning the conditions under which the female advantage in the detection of change in an array of objects occurs. The findings are discussed within an evolutionary conceptual framework.

A Concerted Action Of Estradiol And Insulin Like Growth Factor I Underlies Sex Differences In Mood Regulation By Exercise

Mood homeostasis present sexually dimorphic traits which may explain sex differences in the incidence of mood disorders. We explored whether diverse behavioral-setting components of mood may be differentially regulated in males and females by exercise, a known modulator of mood. We found that exercise decreases anxiety only in males. Conversely, exercise enhanced resilience to stress and physical arousal, two other important components of mood, only in females. Because exercise increases brain input of circulating insulin-like growth factor I (IGF-I), a potent modulator of mood, we explored whether sex-specific actions of exercise on mood homeostasis relate to changes in brain IGF-I input. We found that exercise increased hippocampal IGF-I levels only in cycling females. Underlying mechanism involved activation of estrogen (E2) receptors in brain vessels that led to increased uptake of serum IGF-I as E2 was found to stimulate IGF-I uptake in brain endothelial cells. Indeed, modulatory effects of exercise on mood were absent in female mice with low serum IGF-I levels or after either ovariectomy or administration of an E2 receptor antagonist. These results suggest that sex-specific brain IGF-I responses to physiological stimuli such as exercise contribute to dimorphic mood homeostasis that may explain sex differences in affective disorders.

Sex differences in visuospatial and navigational working memory: the role of mood induced by background music.

Sex differences in visuospatial abilities are long debated. Men generally outperform women, especially in wayfinding or learning a route or a sequence of places. These differences might depend on women's disadvantage in underlying spatial competences, such as mental rotation, and on the strategies used, as well as on emotions and on self-belief about navigational skills, not related to actual skill-levels. In the present study, sex differences in visuospatial and navigational working memory in emotional contexts were investigated. Participants' mood was manipulated by background music (positive, negative or neutral) while performing on the Corsi Block-tapping Task (CBT) and Walking Corsi (WalCT) test. In order to assess the effectiveness of mood manipulation, participants filled in the Positive and Negative Affect Schedule before and after carrying out the visuospatial tasks. Firstly, results showed that after mood induction, only the positive affect changed, whereas the negative affect remained unconfounded by mood and by sex. This finding is in line with the main effect of 'group' on all tests used: the positive music group scored significantly higher than other groups. Secondly, although men outperformed women in the CBT forward condition and in the WalCT forward and backward conditions, they scored higher than women only in the WalCT with the negative background music. This means that mood cannot fully explain sex differences in visuospatial and navigational working memory. Our results suggest that sex differences in the CBT and WalCT can be better explained by differences in spatial competences rather than by emotional contexts.

Why sickness hurts: A central mechanism for pain induced by peripheral inflammation

Low-grade systemic inflammation has been implicated in chronic pain, as well as in comorbid diseases like depression and fatigue. We have previously shown that women’s pain perception and regulation is more affected by systemic inflammation than that of men. Here we investigated the neural substrates underlying these effects using an fMRI paradigm previously employed in a clinical population. Fifty-one participants (29 women) were injected with 0.6ng/kg lipopolysaccharide (LPS) or saline to induce a peripheral inflammatory response. The subjects were then tested with a pressure pain fMRI paradigm designed to capture descending pain inhibitory activity 2h after injection, and blood was sampled for cytokine analysis.The subjects injected with LPS became more pain sensitive compared to the placebo group, and the heightened pain sensitivity was paralleled by decreased activity in the ventrolateral prefrontal cortex and the rostral anterior cingulate cortex (rACC) compared to placebo; areas involved in descending pain regulation. The LPS group also had higher activity in the anterior insular cortex, an area underpinning affective and interoceptive pain processing. Women displayed overall less pain-evoked rACC activity compared to men, which may have rendered women less resilient to immune provocation, possibly explaining sex differences in LPS-induced pain sensitivity. Our findings elucidate the pain-related brain circuits affected by experimental peripheral inflammation, strengthening the theoretical link between systemic inflammation and weakened pain regulation in chronic pain disorders. The results further suggest a possible mechanism underlying the female predominance in many chronic pain disorders.

Tracing the associations between sex, the atypical and the combined atypical-melancholic depression subtypes: A path analysis

BackgroundNumerous studies have examined determinants leading to preponderance of women in major depressive disorder (MDD), which is particularly accentuated for the atypical depression subtype. It is thus of interest to explore the specific indirect effects influencing the association between sex and established depression subtypes. MethodsThe data of 1624 subjects with a lifetime diagnosis of MDD derived from the population-based PsyCoLaus data were used. An atypical (n=256), a melancholic (n=422), a combined atypical and melancholic features subtype (n=198), and an unspecified MDD group (n=748) were constructed according to the DSM-IV specifiers. Path models with direct and indirect effects were applied to the data. ResultsPartial mediation of the female-related atypical and combined atypical-melancholic depression subtypes was found. Early anxiety disorders and high emotion-orientated coping acted as mediating variables between sex and the atypical depression subtype. In contrast, high Body Mass Index (BMI) served as a suppression variable, also concerning the association between sex and the combined atypical-melancholic subtype. The latter association was additionally mediated by an early age of MDD onset and early/late anxiety disorders. LimitationsThe use of cross-sectional data does not allow causal conclusions. ConclusionsThis is the first study that provides evidence for a differentiation of the general mechanisms explaining sex differences of overall MDD by depression subtypes. Determinants affecting the pathways begin early in life. Since some of them are primarily of behavioral nature, the present findings could be a valuable target in mental health care.

Abstract 15770: Sex Differences in Growth Rates of Thoracic Aortic Aneurysms

Introduction: Thoracic aortic aneurysm (TAA) is a deadly disease of increasing prevalence. Although more prevalent in men, TAA-related mortality is higher in women. In addition, women develop acute aortic syndromes at smaller aneurysm diameters, independently of body size. However, the basis for worse TAA outcomes in women is unknown. Since faster TAA growth is an established risk factor for acute aortic syndromes, we sought to determine the role of sex on TAA growth. Hypothesis: We hypothesized that TAA growth rates differ based on sex. Methods: Fifty three consecutive unoperated subjects with TAA who had serial aneurysm measurements by CT, MRI or echocardiography were prospectively recruited. Aneurysm size was measured systematically by an imaging cardiologist (TC); growth rate was calculated as mm/year. In multivariable linear regression, the association of female sex with aneurysm growth rate was assessed after adjustment for age, and then additional adjustment for body surface area, baseline aneurysm size, beta-blocker use and history of hypertension, diabetes, dyslipidemia and smoking. Results: Thirty seven (70%) subjects were men; mean±SD age was 63.7±11.9 years (62.2±12.3 in men, 66.9±10.6 in women, P =0.17). Thirty (57%) subjects had degenerative TAAs, the remainder had heritable TAAs. Fifteen had maximal dilation at the aortic root, and 38 at the ascending aorta. Baseline aneurysm size and follow-up time were 45.4±4.5 mm and 3.01±2.9 years, respectively, and not different between men and women ( P &gt;0.05 for both). Aneurysm growth rate was 1.22±1.09 mm/year in women and 0.68±0.68 mm/year in men. Female sex was significantly associated with greater aneurysm growth rate after adjustment for age (β±SE: 0.25±0.13, P =0.05) and additional adjustment for confounders (β±SE: 0.30±0.14, P =0.03). Notably, baseline aneurysm size was not associated with TAA growth (β±SE: -0.01±0.0.03, P =0.72). Conclusions: In subjects with TAA from different etiologies, reflecting clinical practice, aneurysm growth rates are greater in women than men. Our findings may potentially explain sex differences in TAA outcomes, providing a foundation for future investigations aimed at assessing causes for faster aneurysm growth and acute aortic syndromes in women.

Sex Differences in Early-Age Mortality: The Preconception Origins Hypothesis.

The preconception origins hypothesis holds that some of the preconception and prenatal environmental factors that have been shown to determine the offspring sex ratio also explain sex differences in early-age mortality (Pongou 2013). It extends and complements the biological hypothesis, which affirms that the mortality sex gap originates in biological and genetic differences between the sexes. As such, it offers a broad framework for understanding changes in male–female differences in early-age mortality across space and over time. I argue that this hypothesis is consistent with the concurrent increase in the proportion of female births and in the relative mortality of female to male infants in the United States since World War II. (This abstract was borrowed from another version of this item.)