Influence Sex Differences Research Articles

Factors influencing sex differences in numbers of tuberculosis suspects at diagnostic centres in Pakistan

DOTS-reporting tuberculosis (TB) diagnostic centres across Pakistan. To quantitatively investigate the influence of diagnostic centre characteristics on the number of female and male TB suspects registered at diagnostic centres. Ten districts were selected across the four provinces of Pakistan. Data were collected on male and female TB suspects in all diagnostic centres within each district. A structured questionnaire was used to collect data on characteristics of the diagnostic centres. Multiple linear regression analysis was conducted to evaluate the influence of each characteristic on sex differences in the numbers of suspects. Two diagnostic centre characteristics were associated with higher numbers of female than male TB suspects: catering to the local catchment area (P = 0.001) and being accessible on foot (P = 0.002). The following characteristics were associated with higher numbers of male than female TB suspects: being open after 2 pm (P = 0.041), having more than five doctors working at the centre (P = 0.019), and having more than 100 suspects registered per quarter (P = 0.008). Smaller, local diagnostic centres that are accessible on foot registered more female than male TB suspects. More centralised facilities located further from homes, larger facilities and those with evening opening hours registered more male than female suspects.

Tracking of physical activity during middle school transition in Iranian adolescents

Objective: The purpose of this longitudinal study was to examine changes in physical activity behavior, psychological factors and interpersonal influences associated with exercise behavior during the transition from secondary school to high school in Sanandaj, Iran. Design: Data were collected from students in 2006 ( N = 1,073), of whom 844 provided follow-up data in 2009. Setting: The students were in high school in 2009 (51% male) with a mean age of 16.42 ± 1.73 years. Method: Physical activity-related cognitions, interpersonal influences, and physical activity behavior were measured using self-report questionnaires. To assess the effects of time and sex on psychosocial factors, analysis of variances (ANOVAs) were conducted. The relative stability of physical activity psychosocial correlates from wave 1 through wave 2 was assessed using Pearson product-moment correlations. Results: There were significant differences according to sex across time for physical activity, psychological variables and interpersonal influences associated with exercise activities. The girls were less active than boys at both time points. Girls reported lower self-efficacy and perceived more barriers and fewer perceived benefits for physical activity over time. Interpersonal influences on activity were more stable for girls than boys. Conclusion: The results offer evidence for decreasing physical activity in boys and girls and sex differences in cognitive variables and interpersonal influences. This is important for understanding how to address the problem of physical inactivity among Iranian youth.

Effects of suppressing gonadal hormones on response to novel objects in adolescent rats

Human adolescents exhibit higher levels of novelty-seeking behaviour than younger or older individuals, and novelty-seeking is higher in males than females from adolescence onwards. Gonadal hormones, such as testosterone and estradiol, have been suggested to underlie age and sex difference in response to novelty; however, empirical evidence in support of this hypothesis is limited. Here, we investigated whether suppressing gonadal hormone levels during adolescence affects response to novelty in laboratory rats. Previously, we have shown that male adolescent Lister-hooded rats (postnatal day, pnd, 40) exhibit a stronger preference than same-aged females for a novel object compared to a familiar object. In the current study, 24 male and 24 female Lister-hooded rats were administered with Antide (a gonadotrophin-releasing hormone antagonist), or with a control vehicle solution, at pnd 28. Antide provided long-term suppression of gonadal hormone production, as confirmed by ELISA assays and measurement of internal organs. Response to novel objects was tested at pnd 40 in Antide-treated and control subjects using a ‘novel object recognition’ task with a short (2-minute) inter-trial interval. In support of previous findings, control males exhibited a stronger preference than control females for novelty when presented with a choice of objects. Antide-treated males exhibited a significantly lower preference for novel objects compared to control males, whilst Antide-treated females did not differ significantly from control females in their preference for novelty. Antide treatment did not affect total time spent interacting with objects. We discuss how gonadal hormones might influence sex differences in preference for novelty during adolescence.

Progesterone effects on the discriminative stimulus, subjective and performance effects of triazolam in healthy, premenopausal women.

There is accumulating evidence that sex plays a critical role in drug abuse. Female sex hormones have been shown to affect central nervous system function and modulate the effects of drugs of abuse. For example, γ-aminobutyric acid type A (GABA(A)) receptor function is positively modulated by progesterone metabolites. There is evidence from preclinical in-vitro and in-vivo studies as well as some clinical research suggesting that progesterone and its metabolites may enhance the behavioral effects of benzodiazepines, which also serve as positive modulators of GABA(A) receptors. The purpose of this experiment was to determine the independent and combined discriminative stimulus, subjective and psychomotor effects of progesterone and triazolam in healthy adult premenopausal women. Oral micronized progesterone (100 mg), triazolam (0.06, 0.12 and 0.25 mg/70 kg) and placebo were administered to healthy, premenopausal women (n=9) under conditions of low circulating sex hormones. Triazolam alone functioned as a discriminative stimulus and produced prototypical sedative-like effects (e.g., performance impairment, enhanced reports of sedative effects). Progesterone alone produced sedative-like effects on several subjective and performance measures, and the dose combination effects of progesterone and triazolam on several subjective measures of drug effect were similar to the summation of the two drug effects in isolation. Progesterone did not substitute for or modify the discriminative stimulus effects of triazolam. These results suggest that the parent hormone, progesterone, and triazolam have discordant neuropharmacological mechanisms of action. Additional research is necessary to determine the degree to which neurosteroids influence sex differences in benzodiazepine use and abuse.

Sex, temperament, and family context: how the interaction of early factors differentially predict adolescent alcohol use and are mediated by proximal adolescent factors.

Adolescent alcohol use is common and has serious immediate and long-term ramifications. While concurrent individual and context factors are robustly associated with adolescent alcohol use, the influence of early childhood factors, particularly in interaction with child sex, are less clear. Using a prospective community sample of 362 (190 girls), this study investigated sex differences in the joint influence of distal childhood and proximal adolescent factors on Grade 10 alcohol use. All risk factors and two-way early individual-by-context interactions, and interactions of each of these with child sex, were entered into the initial regression. Significant sex interactions prompted the use of separate models for girls and boys. In addition to the identification of early (family socioeconomic status, authoritative parenting style) and proximal adolescent (mental health symptoms, deviant friends) risk factors for both girls and boys, results highlighted important sex differences. In particular, girls with higher alcohol consumption at Grade 10 were distinguished by the interaction of early temperamental disinhibition and exposure to parental stress; boys with higher alcohol consumption at Grade 10 were distinguished primarily by early temperamental negative affect. Results have implications for the timing and type of interventions offered to adolescents.

Does Your Supervisor Stress You Out? How Support Influences Sex Differences in Stress Among Immigrants

Despite the influx of immigrants in the American workplace, little is known about their well-being. The authors built on literature pertaining to gender-specific stressors and organizational support theory to examine a model of stress for immigrants. Analysis of a national, archival data set ( N = 150) demonstrated that, consistent with research involving U.S. citizens, immigrant women reported higher stress than immigrant men. The authors extended the literature, however, by showing that the sex–stress relationship is not straightforward for this population. Specifically, supervisor support moderated the effect of sex such that male–female stress differences were twice as large when supervisors were less supportive. Despite the influx of immigrants in the American workplace, little is known about their well-being. The authors built on literature pertaining to gender-specific stressors and organizational support theory to examine a model of stress for immigrants. Analysis of a national, archival data set ( N = 150) demonstrated that, consistent with research involving U.S. citizens, immigrant women reported higher stress than immigrant men. The authors extended the literature, however, by showing that the sex–stress relationship is not straightforward for this population. Specifically, supervisor support moderated the effect of sex such that male–female stress differences were twice as large when supervisors were less supportive.

National School Lunch Program Participation and Sex Differences in Body Mass Index Trajectories of Children From Low-Income Families

To investigate participation patterns in the National School Lunch Program (NSLP) among low-income children from kindergarten to fifth grade and to examine the ways in which participation influences sex differences in the trajectories of body mass index (BMI) through the eighth grade. Longitudinal, secondary data analysis. Sample of low-income US children who entered kindergarten in 1998. Girls (n = 574) and boys (n = 566) from low-income families who participated in the Early Childhood Longitudinal Study, Kindergarten Cohort. Participation in the NSLP. Temporary and persistent patterns of NSLP participation, and age-specific and sex-specific BMI raw scores calculated at 5 data points. Among the low-income children who attended schools that participated in the NSLP, both the children who persistently participated in the program and those who temporarily participated in the program displayed similar socioeconomically disadvantaged factors. Nonlinear mixed models indicated a larger rate of change in BMI (ie, an increase) among low-income, participating girls than among low-income, nonparticipating girls; however, mean BMIs did not significantly differ between low-income girls who participated and those who did not participate. No significant differences were observed among low-income boys. Results suggest that participation in the NSLP is associated with rapid weight gain for low-income girls but not for low-income boys.

Sex differences in force steadiness in three positions of the forearm

The purpose of this study was to examine force steadiness in three positions of the forearm in young men and women across a variety of force levels. Eight young men and eight young women performed three maximum voluntary contractions (MVCs) in the neutral, supinated, and pronated forearm positions. Viewing a target line on a computer screen, subjects performed submaximal isometric contractions relative to their own MVC at 2.5, 5, 10, 25, 50, and 75% in each of the three forearm positions. Force steadiness was determined as the coefficient of variation (standard deviation around the mean force). A repeated-measures three-way ANOVA was used to assess the differences in force steadiness between sex, position, and force level. Men were stronger than women in all three forearm positions. Overall, men were steadier than women across all force levels and forearm positions. The neutral and supinated positions were equally strong and steady, and the pronated position was the weakest and least steady position. The forearm was most steady between 25 and 75% MVC, and least steady at the lower force levels. When correlations were run between MVC and coefficient of variation at all force levels and all forearm positions, a strong negative relationship was found (r=-0.49). In conclusion, men were stronger, as well as steadier, than women. The neutral and supinated forearm positions were both stronger and steadier than the pronated position. Results suggest that one of the primary factors influencing sex differences in force steadiness is absolute strength.

Sex Differences in Epigenetic Regulation of the Estrogen Receptor-α Promoter within the Developing Preoptic Area

Sex differences in the brain are largely organized by a testicular hormone surge that occurs in males shortly after birth. Although this hormone surge is transient, sex differences in brain and behavior are lasting. Here we describe a sex difference in DNA methylation of the estrogen receptor-alpha (ERalpha) promoter region within the developing rat preoptic area, with males exhibiting more DNA methylation within the ERalpha promoter than females. More importantly, we report that simulating maternal grooming, a form of maternal interaction that is sexually dimorphic with males experiencing more than females during the neonatal period, effectively masculinizes female ERalpha promoter methylation and gene expression. This suggests natural variations in maternal care that are directed differentially at males vs. females can influence sex differences in the brain by creating sexually dimorphic DNA methylation patterns. We also find that the early estradiol exposure may contribute to sex differences in DNA methylation patterns. This suggests that early social interaction and estradiol exposure may converge at the genome to organize lasting sex differences in the brain via epigenetic differentiation.

Sex Differences in the Serotonergic Influence on the Hypothalamic-Pituitary-Adrenal Stress Axis

Sex Differences in the Serotonergic Influence on the Hypothalamic-Pituitary-Adrenal Stress Axis

Sex Differences in the Serotonergic Influence on the Hypothalamic-Pituitary-Adrenal Stress Axis

Appropriate interactions between serotonin (5-HT) and stress pathways are critical for maintaining homeostasis. Dysregulation of hypothalamic-pituitary-adrenal (HPA) stress axis is a common feature in affective disorders in which an involvement of 5-HT neurocircuitry has been implicated in disease vulnerability and treatment responsiveness. Because there is a greater prevalence of affective disorders in women, sex differences in the 5-HTergic influence on stress pathways may contribute to disease disparity. Therefore, our studies compared stress or citalopram-induced corticosterone levels in male and female mice. To determine whether sex-dependent HPA axis responsiveness was mediated by the difference in testosterone levels, testosterone-treated females were also examined. Gene expression patterns in 5-HTergic and stress neurocircuitry were analyzed to determine sites of potential sex differences and mechanisms of testosterone action. As expected, restraint stress corticosterone levels were higher in intact females and were masculinized by testosterone. Interestingly, citalopram administration independent of stress resulted in a greater corticosterone response in females, which was also masculinized by testosterone. Analyses along the 5-HT-HPA axis revealed sex differences including greater pituitary 5-HT receptors and adrenal weights in females. Moreover, in stress-regulatory regions, we found sex differences in glucocorticoid receptor and glutamic acid decarboxylase expression supportive of greater inhibitory modulation and feedback potential in males. Taken together, these data suggest that multiple sites related to 5-HTergic stimulation, corticosterone production, and negative feedback of HPA neurocircuitry combine to produce higher female stress responsiveness. These studies support a potential for sex-specific involvement of 5-HT and stress pathways in the etiology of affective disorders.

Genetic and Environmental Contributions to Childhood Temperament in South Korean Twins

Although genetic basis of childhood temperament has been well documented in western populations, little is known about whether genes play an important role in childhood temperament in East Asians. The present study examined mother's ratings of Emotionality, Activity, and Sociability (EAS) in 894 pairs of 2- to 9-year-old South Korean twins. The best-fitting model indicated that 34 to 47% of the variances of the EAS were attributable to genetic factors, with the remaining variances being due to the effects of environmental experiences unique to each child. Common family environmental factors were negligible. Genetic variances for Activity and Sociability were primarily nonadditive, whereas those for Emotionality were additive. In spite of well known cultural differences in child rearing practices, social values, and the mean levels of temperament between East Asian and western populations, the pattern of additive vs. nonadditive gene actions and heritability estimates found in the present sample were remarkably similar to those reported in western twin samples. There were no significant age or sex differences in genetic or environmental influences. Overall, these results corroborate cross cultural generality of genetic influences on childhood temperament.

Arbitrary Social Norms Influence Sex Differences in Romantic Selectivity

Men tend to be less selective than women when evaluating and pursuing potential romantic partners. The present experiment employed speed-dating procedures to test a novel explanation for this sex difference: The mere act of physically approaching a potential romantic partner (vs. being approached), a behavior that is more characteristic of men than of women, increases one's attraction to that partner. This hypothesis was supported in a sample of speed daters (N = 350) who attended a heterosexual event where either men (eight events) or women (seven events) rotated from one partner to the next while members of the other sex remained seated. Rotators were significantly less selective than were sitters, which meant that the tendency for men to be less selective than women at events where men rotated disappeared at events where women rotated. These effects were mediated by increased self-confidence among rotators relative to sitters.

Sex differences in children’s free drawings and their relationship to 2D:4D ratio

The hypothesis that prenatal androgen exposure influences sex differences in children’s drawings was examined in a population of K-3 elementary school students. Various characteristics of children’s free drawings were assessed by age, and those that showed sex differences were compared with 2D:4D. Overall, boys had smaller 2D:4D ratios on the right hand, used a smaller proportion of warm colors relative to cold colors, covered less of the paper, used fewer pinks, purples, and yellows, and used more black/gray. Girls’ drawings were more likely to contain flowers, animals, and sky and boys’ drawings were more likely to contain people. When analyzed by grade level (K and 1st vs. 2nd and 3rd), sex differences in the number of colors, proportion of warm colors, and number of pinks and purples used were present only in the older children, suggesting a social influence on these sex differences. On the other hand, there were significant correlations in the older girls between right 2D:4D ratio and the use of pinks and purples. These observations support the role of social factors in the development of sex differences in children’s free drawings, but also suggest an influence of early androgen levels on girls’ free drawings.

Sex Differences in Genetic and Environmental Influences on Obsessive–Compulsive Symptoms in South Korean Adolescent and Young Adult Twins

Recent molecular genetic studies provide suggestive evidence for sexual dimorphism in genetics of obsessive-compulsive disorder. However, only a few twin studies have addressed the question of sex differences in genetic and environmental contributions to variation of obsessive-compulsive symptoms. The aim of the present study was to estimate genetic and environmental influences on obsessive-compulsive symptoms in South Korean twins, with a special emphasis on sex difference. In total, 751 adolescent and young adult twin pairs (ages: 13-23 years) completed a Korean version of the 30 items of the Maudsley Obsessional - Compulsive Inventory (MOCI) through a mail survey. A sum of the answers for the 30 items was calculated to represent a total score for obsessive-compulsive symptoms (hereafter, the MOCIT). Males had significantly higher variance of the MOCIT than did females. In males, monozygotic (MZ) twin correlation was significantly higher than dizygotic (DZ) twin correlations (.56 vs. .24), whereas in females, MZ and DZ twin correlations were not significantly different from each other (.39 vs. .36). The general sex-limitation model was applied to the twin data. The results of model-fitting analyses indicated that the unstandardized genetic variance as well as heritability estimate (53% vs. 41%) for the MOCIT was higher in males than in females. However, shared environmental influences did not attain statistical significance perhaps due to insufficient statistical power.

Size matters: cerebral volume influences sex differences in neuroanatomy.

Biological and behavioral differences between the sexes range from obvious to subtle or nonexistent. Neuroanatomical differences are particularly controversial, perhaps due to the implication that they might account for behavioral differences. In this sample of 200 men and women, large effect sizes (Cohen's d > 0.8) were found for sex differences in total cerebral gray and white matter, cerebellum, and gray matter proportion (women had a higher proportion of gray matter). The only one of these sex differences that survived adjustment for the effect of cerebral volume was gray matter proportion. Individual differences in cerebral volume accounted for 21% of the difference in gray matter proportion, while sex accounted for an additional 4%. The relative size of the corpus callosum was 5% larger in women, but this difference was completely explained by a negative relationship between relative callosal size and cerebral volume. In agreement with Jancke et al., individuals with higher cerebral volume tended to have smaller corpora callosa. There were few sex differences in the size of structures in Broca's and Wernicke's area. We conclude that individual differences in brain volume, in both men and women, account for apparent sex differences in relative size.

Equal, but different?

PurposeThe purpose of this paper is to analyze how the status and functional responsibilities of female human resource (HR) directors vary cross‐nationally and how gender egalitarian cultural values affect role differences between female and male HR directors.Design/methodology/approachA cross‐country comparison of HR directors involving 22 countries based on the 2004 Cranet survey.FindingsConsistent with the hypotheses, gender egalitarian values reduce sex‐role differences for strategic integration and for traditionally female‐stereotyped HR functions. However, there is no support for the notion that egalitarian values influence sex differences for male‐stereotyped HR functions. Since, the data indicate higher levels of involvement of female HR directors in male‐stereotyped HR functions in 12 out of 22 countries, unequal distribution of functional responsibility is interpreted as an indicator for sex differences in administrative workload.Originality/valueMacro cultural factors matter for sex‐role differences in strategic integration and functional responsibilities of HR directors. The effects of gender egalitarian values have greater impact on reducing vertical differences than horizontal differences.

Sex Differences in Risk-Taking? Evidence from Female Representation in Legislatures

History's societies vary on numerous dimensions, but appear relatively homogenous in how they distribute socioeconomic status across sexes. This homogeneity begs the question of whether forces that are robust to formal and informal institutions influence sex differences in status. We address this question by empirically evaluating evolutionary models of hierarchical attainment where sex-differences in risk-taking play an axiomatic role. These models imply that (1) winner-take-all games favor males, but (2) successful females maintain greater skill on average. We find support for these implications in how the sex-composition of national legislatures differs across electoral mechanisms (i.e., majoritarian chambers employ a significantly greater proportion of males) and how US Representatives' re-election prospects differ by sex (i.e., females enjoy significantly longer durations). These results cannot easily be dismissed as artifacts of endogeneity bias, and alternative models can (at best) rationalize our cross-sectional or time series results, but not both.

Mothers' and fathers' socialization of preschoolers' physical risk taking

This study examined how parents influence sex differences in young children's physical risk taking behaviors. Eighty three- and four-year old, mostly middle class and Caucasian children climbed across a five-foot high catwalk and walked across a three-foot high beam under their mother or father's supervision. Based on average preschooler gross motor capabilities, both of these activities posed potential threats to preschoolers' physical safety without proper parental monitoring. Analyses revealed that fathers of daughters monitored their children more closely than did fathers of sons. In contrast, mothers of daughters and mothers of sons monitored their children similarly. Differential treatment of preschool-aged girls and boys in risk taking situations is discussed as a contributor to sex differences found in children's physical risk taking and unintentional injuries.

Foetal testosterone and the child systemizing quotient

This study examines foetal testosterone (fT) levels (measured in amniotic fluid) as a candidate biological factor, influencing sex differences in systemizing. Systemizing is a cognitive process, defined as the drive to analyze or construct systems. A recent model of psychological sex differences suggests that this is a major dimension in which the sexes differ, with males being more drawn to systemize than females. Participants included 204 children (93 female), age 6–9 years, taking part in a long-term study on the effects of fT. The systemizing quotient – children’s version was administered to these mothers to answer on behalf of their child. Males (mean = 27.79 ± 7.64) scored significantly higher than females (mean = 22.59 ± 7.53), confirming that boys systemize to a greater extent than girls. Stepwise regression analysis revealed that fT was the only significant predictor of systemizing preference when the sexes were examined together. Sex was not included in the final regression model, suggesting that fT levels play a greater role than the child’s sex in terms of differences in systemizing preference. This study suggests that the levels of fT are a biological factor influencing cognitive sex differences and lends support to the empathizing–systemizing theory of sex differences.