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At least 253 records · Page 14Linked to original sources
PubMed1999

Sex differences in sensorimotor gating of the human startle reflex: all smoke?

RATIONALE: A recent report described sex differences in the effects of nicotine use and withdrawal on prepulse inhibition of acoustic startle (PPI), but no sex differences in PPI in non-smokers. OBJECTIVE: To determine whether previously reported male>female acoustic PPI reflect sex differences in smoking effects on PPI, rather than simple sex differences in the regulation of PPI. A retrospective analyses of >600 carefully screened normals tested over the past 12 years was completed. RESULTS: Male>female acoustic PPI was detected in analyses that included: 1) all subjects; or 2) self-declared non-smokers. CONCLUSIONS: Sex differences in PPI cannot be accounted for by smoking history, because they are present across a large sample of non-smoking normal controls.

Acoustic Stimulation↗
PubMed2006

Testing descriptive hypotheses regarding sex differences in the development of conduct problems and delinquency.

Accurate descriptions of sex differences in the development of childhood conduct problems and adolescent delinquency will inform theories of their causes in fundamentally important ways. Using data on 4,572 offspring of a national sample of women, we tested descriptive hypotheses regarding sex differences. As predicted, the magnitude of sex differences varied with age, suggesting that multiple processes differentially influence levels of these behaviors in females and males across development. During childhood, boys scored lower on measures of cognitive ability and exhibited lower sociability and compliance and greater hyperactivity, oppositional behavior, and conduct problems. Most of these variables were associated with childhood conduct problems and adolescent delinquency equally in females and males, but maternal delinquency and early childhood sociability were correlated more strongly with childhood conduct problems in males and childhood compliance predicted adolescent delinquency more strongly in females. Both sexes exhibited both childhood-onset and adolescent-onset trajectories of delinquency. Although more males followed a childhood-onset trajectory, there were few sex differences in the early childhood risk correlates of either delinquency trajectory.

Adolescent↗
PubMedDate not supplied

Sex differences in cognition are stable over a 10-year period in adulthood and old age.

Sex differences in declarative memory and visuospatial ability are robust in cross-sectional studies. The present longitudinal study examined whether sex differences in cognition were present over a 10-year period, and whether age modified the magnitude of sex differences. Tests assessing episodic and semantic memory, and visuospatial ability were administered to 625 nondemented adults (initially aged 35-80 years), participating in the population-based Betula study at two follow-up occasions. There was stability of sex differences across five age groups and over a 10-year period. Women performed at a higher level than men on episodic recall, face and verbal recognition, and semantic fluency, whereas men performed better than women on a task-assessing, visuospatial ability. Sex differences in cognitive functions are stable over a 10-year period and from 35 to 90 years of age.

Adult↗
PubMed2002

A meta-analysis of sex differences in romantic attraction: do rating contexts moderate tactic effectiveness judgments?

Although a number of studies have explored perceived sex differences in romantic attraction effectiveness, no research has systematically examined whether different rating contexts might moderate effectiveness judgments. In a meta-analytic review of romantic attraction research, four potential moderating variables were examined: temporal context (unspecified, long-term, short-term), manipulation form (self-promotion, competitor derogation), attraction type (general, retention, poaching), and sex of rater (mixed, same, opposite). Although perceived sex differences in physical appearance and resource-related tactics remained stable across most moderating variables, sex differences did vary across some rating contexts. For example, perceptions of sex differences in the effectiveness of appearance-related attraction tactics were much stronger in the context of self-promotion (d = -.77) compared with the competitor derogation context (d = -.17). Resource-related tactics of attraction displayed the opposite pattern, with significantly larger perceived sex differences in the context of competitor derogation (d =.93) than in self-promotion (d =.68). Discussion focused on the implications of sex difference variability and stability across rating contexts for evolutionary theories of romantic attraction.

Courtship↗
PubMedDate not supplied

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls.

BACKGROUND: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. AIM: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). SUBJECTS AND METHODS: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. RESULTS: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). CONCLUSION: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference.

Absorptiometry, Photon↗
PubMed2005

Sex differences and the factor of time in solving Vandenberg and Kuse mental rotation problems.

In accounting for the well-established sex differences on mental rotation tasks that involve cube stimuli of the Shepard and Metzler (Shepard & Metzler, 1971) kind, performance factors are frequently invoked. Three studies are presented that examine performance factors. In Study 1, analyses of the performance of a large number of subjects (n=1765) that performed the Vandenberg and Kuse (1976) mental rotation test (MRT) under standard conditions showed that the magnitude of the sex differences increases as subjects proceed through the sequence of problems, and that fewer females than males reach the last problems in a problem set. This supports the role of time constraints in sex differences on the MRT. Study 2 compared the magnitude of sex differences for subjects (n=212) who did the MRT under standard conditions (T1), and with double the time (T2) allowed for the test. No significant reduction in the magnitude of sex differences was observed-even though the overall scores under T2 increased markedly for both sexes. Study 3 examined the suggestion by that mental rotation differences arise because females spend more time than males in assuring that stimuli that do not match do indeed not match, with no sex differences for matching stimuli. This hypothesis was not supported for a sample of 20 males and 26 females. We conclude that performance factors may play a role in sex difference on mental rotation tasks, but do not account for all of the differences.

Adult↗
PubMedDate not supplied

Hormonal and immunological mechanisms mediating sex differences in parasite infection.

The prevalence and intensity of infections caused by protozoa, nematodes, trematodes, cestodes, and arthropods is higher in males than females. The primary thesis of this review is that immunological differences exist between the sexes that may underlie increased parasitism in males compared to females. Several field and laboratory studies link sex differences in immune function with circulating steroid hormones; thus, the roles of sex steroids, including testosterone, oestradiol, and progesterone, as well as glucocorticoids will be discussed. Not only can host hormones affect responses to infection, but parasites can both produce and alter hormone concentrations in their hosts. The extent to which changes in endocrine-immune interactions following infection are mediated by the host or the parasite will be considered. Although males are more susceptible than females to many parasites, there are parasites for which males are more resistant than females and endocrine-immune interactions may underlie this sex reversal. Finally, although immunological differences exist between the sexes, genetic and behavioural differences may explain some variability in response to infection and will be explored as alternative hypotheses for how differences between the sexes contribute to dimorphic responses to parasites.

Behavior↗
PubMed2005

Sex differences in spatial visualization and episodic memory as a function of alcohol consumption.

AIMS: Sex differences in visuospatial ability as well as episodic memory have been reliably demonstrated, irrespective of alcoholism. Studies in alcoholics have consistently documented cognitive deficits in visuospatial ability, problem solving and memory function. This cross-sectional, population-based study examined if sex differences in cognitive performance could be impacted by alcohol consumption. METHODS: Drinking data were collected from 2224 randomly sampled adults, aged between 35 and 85 years, who participated in the Betula study on memory, health and aging. Participants were classified into non-, light, moderate and heavy drinking subgroups based on sex-adjusted normative values. Cognitive tasks demonstrating clear sex differences, such as episodic memory tasks (favouring women) and spatial visualization tasks (favouring men), were conducted and performance was assessed by sex and the drinking group. RESULTS: After controlling for age and education, overall analyses found expected sex differences in episodic memory and spatial visualization that were apparent across the entire population. When these sex differences were examined by drinking group, visuospatial performance favouring men disappeared for the moderate to heavy drinking groups, but higher performance by women on episodic memory tasks was consistent across all levels of alcohol consumption. Traditional biomarkers of increased alcohol consumption (GGT and MCV) correlated with the reported drinks/day. CONCLUSIONS: These results lend support to the theory that moderate alcohol intake may be beneficial to cognitive function in women, but not necessarily in men.

Adult↗
PubMed2001

Sex differences in cocaine-induced behavioral sensitization.

To further understand how sex differences affect the development and maintenance of sensitization, 48 adult Fischer rats (24 female and 24 male) received chronic administration (14 days) of cocaine (15 mg/kg, i.p.) or saline or a challenge dose (7 days after chronic cocaine administration). Sex differences were observed in the development and maintenance of cocaine-induced total locomotor, ambulatory and rearing activity. Although, overall cocaine administration increased stereotypic activity in both male and female rats, female rats had significantly higher stereotypic activity than male rats across the three behavioral test days (1, 7 and 14). Female rats had statistically significant higher benzoylecognine levels after acute cocaine administration than male rats. However, no differences between male and female rats in benzoylecognine plasma levels were observed after chronic and challenge doses of cocaine administration. Interestingly, after acute and challenge cocaine administration, corticosterone levels were significantly higher in female rats when compared to male rats. This study confirms previous reports that there are sex differences in the behavioral response to cocaine. Moreover, this study expands previous studies by demonstrating that sex differences occur in only certain aspects of cocaine-induced behavioral activation and the development and maintenance of cocaine-induced behavioral sensitization.

Animals↗
PubMed1979

Sex differences in response to hepatitis B virus. III. Responses to HBV and sex of donor and recipient in kidney and bone marrow transplantation.

We proposed the hypothesis that there is an antigen on the hepatitis B virus (HBV) that cross-reacts with a male associated antigen to explain four observations: 1) sex differences in the responses to HBV infection, 2) sex differences in the prevalence of chronic liver diseases associated with hepatitis B, 3) the association of parental responses to HBV with the sex ratio (at birth) of their offspring, and 4) the relation of kidney graft survival with the combination of anti-HBs in the recipients and the sex of the organ donor. Patients with aplastic anemia treated with bone marrow transplantation from HLA identical sibling donors were studied to further test this hypothesis and the results provide additional support. Cross reactivity of HBsAg with H-Y antigen, however, has not been demonstrated.

Anemia, Aplastic↗
PubMed1996

Sex differences in estrogen receptor and progestin receptor induction in the guinea pig hypothalamus and preoptic area.

Quantitative in vitro autoradiography was used to determine if regional sex differences in estrogen receptor (ER) content and/or estrogen responsiveness, as indicated by an increase in progestin receptor (PR), are present in the adult guinea pig brain. Adult male and female guinea pigs were gonadectomized 1 week before subcutaneous injection of 25 micrograms estradiol benzoate (EB)/kg body wt or the sesame oil vehicle. Animals were killed by decapitation 44 h after injection. Unoccupied PRs, and unoccupied and occupied ERs, were measured in discrete brain regions by quantitative in vitro autoradiography using [3H]R5020 and [3H]estradiol as ligands, respectively. In vehicle-injected controls, a higher level of ER was found in the arcuate nucleus (ARC), dorsal medial nucleus (DMN) and ventrolateral nucleus (VLN) of females as compared to males. At 44 h after EB injection, 32-55% of the ERs were occupied; however, EB treatment caused a marked down-regulation of total receptor (calculated as occupied+ unoccupied receptor) in most of the brain regions examined, including the periventricular preoptic area (PVP), medial preoptic area (MPO), bed nucleus of the stria terminalis, paraventricular nucleus, ARC, ventrolateral hypothalamus (VLH), VLN, and DMN. In EB-treated animals, PR binding was detectable in the PVP, MPO, ARC, VLH, and VLN, with higher levels of binding observed in the PVP, MPO, and VLN of the female as compared to the male. No PR binding was observed in oil-injected control animals. These results demonstrate region-specific sex differences in ER as well as estrogen-induced regulation of progestin and ERs in the guinea pig brain. The discordance between the regional distributions of sex differences in ER and estrogen-induced PR implies that sex differences in ER and estrogen-induced PR implies that sex differences in estrogen response may not be clearly linked to a sex difference in receptor number. Instead, sex differences in response may involve differences in receptor number within specific subpopulations of estrogen target cells or may involve differences in ER dynamics.

Animals↗
PubMed1991

Sex differences in elaborative strategies: a developmental analysis.

The present study examined sex differences in the use of elaboration in paired associate learning in adolescence and young adulthood. In Experiment 1, 48 eighth grade and 48 tenth grade students were asked to recall 24 word pairs, half of which were high frequency pairs, and half low frequency pairs. After recall, students reported the type of strategy used for each word pair (reading the pairs carefully, rehearsing the words, using imagery or constructing a verbal connection). Females used elaborative strategies more often, were more likely to recall elaborated pairs, and recalled more word pairs than males at both ages. These effects were observed in both high and low frequency word pairs. There was also a main effect of frequency, with elaboration more common with high frequency word pairs. In Experiment 2, college students performed the same paired-associates learning task, but with the added instruction to describe their elaborations in a sentence. At this age, there was a sex by materials interaction, with sex differences in strategy use only present with low frequency word pairs. These findings indicate that sex differences diminish under more favorable task conditions that encourage strategy use (high frequency word pairs) as males and females become more proficient strategy users, but remain under less favorable circumstances. An examination of the types of elaborations generated by college students indicated although males and females produced similar types of elaborations to the word pairs, sex differences in the recallability of low frequency words appeared with less interactive and more idiosyncratic elaborations.

Adolescent↗
PubMed1998

Sex differences in symptom presentation associated with acute myocardial infarction: a population-based perspective.

OBJECTIVES: To describe sex differences in symptom presentation after acute myocardial infarction (AMI) while controlling for differences in age and other potentially confounding factors. BACKGROUND: Although several studies have examined sex differences in diagnosis, management, and survival after AMI, limited data exist about possible sex differences in symptom presentation in the setting of AMI. METHODS: Community-based study of patients hospitalized with confirmed AMI in all 16 metropolitan Worcester, Mass., hospitals (1990 census population = 437,000). Men (n = 810) and women (n = 550) hospitalized with validated AMI in 1986 and 1988 comprised the study sample. RESULTS: After simultaneously controlling for age, medical history, and AMI characteristics through regression modeling, men were significantly less likely to complain of neck pain (adjusted odds ratio (OR) = 0.52; 95% CI: 0.35, 0.78), back pain (OR = 0.38; 95% CI: 0.26, 0.56), jaw pain (OR = 0.50; 95% CI: 0.31, 0.81), and nausea (O.R. = 0.58; 95% CI: 0.45, 0.75) than women. Conversely, men were significantly more likely to report diaphoresis (OR = 1.27; 95% CI: 1.00, 1.61) than women. There were no statistically significant sex differences in complaints of chest pain though men were more likely to complain of this symptom. CONCLUSIONS: The results of this population-based observational study suggest differences in symptom presentation in men and women hospitalized with AMI. These findings have implications for public and health care provider education concerning recognition of sex differences in AMI-related symptoms and health care seeking behaviors.

Aged↗
PubMed1993

Sex differences in higher functioning people with autism.

Though a sex difference in the incidence of autism has frequently been reported, few studies have considered sex differences in the severity of features associated with autism. The Autism Diagnostic Interview was used to assess the difference between a group of 21 females and 21 males with autism with equivalent chronological nonverbal IQ greater than 60. Males were rated to be more severely autistic than females on several measures of early social development, but not in any other areas. Results are discussed in relationship to hypotheses based on sex differences in other populations.

Activities of Daily Living↗
PubMed1987

Sex differences in addict careers. 2. Becoming addicted.

Sex differences are examined for the period during which addiction develops after initial narcotics use. About 25% of the 546 heroin addicts studied became addicted within 1 month after initial use. More women than men fell into this category, and, on the average, women took less time to become addicted. For the majority of those studied (whose addiction occurred 1 month or longer after initial use), patterns of narcotic use during this phase of the addiction career were not significantly different by sex within Anglo or Chicano groups. Differences between female and male addicts in interpersonal relationships, other substance use, drug dealing, legal employment, and criminal behaviors parallel traditional sex role expectations.

Adult↗
PubMed1995

Acute sex differences in serum LH levels in gonadectomized rats: investigation of pituitary response to GnRH pulse frequency and prolactin secretion as etiological agents.

Gonadectomy results in a striking sex difference in plasma LH levels in adult rats; by 2 days postgonadectomy, serum LH is 5- to 10-fold higher in males than in females. Despite 25 years of work, the site of this sex difference has yet to be determined. Since gonadectomy elevates GnRH pulse frequency, we asked whether a sex difference in pituitary LH secretory response to GnRH pulse frequency underlies the sex difference in serum LH postgonadectomy. Pituitaries from intact and 2-day postgonadectomized male and female rats were perifused for 8 h, receiving either no GnRH (basal) or GnRH pulses (50 ng/ml) at 1 pulse/1.5 h, 1/h or 2/h. Five-minute perifusate fractions were analyzed for LH, FSH, and PRL by RIA. At 1 GnRH pulse/1.5 h, but not other frequencies, pituitaries from gonadectomized males released 1.4-2.8 times more LH per pulse than female pituitaries. Such in vitro sex differences in LH release were not due to higher in vitro prolactin release by female than male pituitaries as suppression of pituitary prolactin secretion by perifusion with the dopamine agonist bromocriptine failed to erase sex differences. Since GnRH pulse frequency in vivo exceeds 1/h following castration, it is unlikely that weak sex differences at frequencies slower than 1/h are relevant to differences in serum LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

A re-examination of sex differences in axon density and number in the splenium of the rat corpus callosum.

Previous work from our laboratory reported a sex difference in axon number in the splenium of the adult rat corpus callosum. However, the cortical origin of the axons that were sampled is unknown and sex differences may exist in the topography of axons in this area. The present study revisits the issue of sex differences in axon number in the splenium. First, the topographical organization of axons in the splenium was investigated. Rats each received single intracortical injections of horseradish peroxidase (HRP). The location of HRP labelled fibers in the corpus callosum was compared across the various injection sites. There is a rostrocaudal organization of axons in the splenium based on rostral to caudal cortical location that does not vary by sex. Second, visual axons, which comprise the posterior fifth (relative to overall length) of the corpus callosum in both sexes, were thoroughly sampled with electron microscopy. Significant dorsoventral and rostrocaudal variation in myelinated and unmyelinated axon density was found. While axon density varied to some extent depending on the sex of the animal, axon number calculations revealed no sex differences in total axon number. Males, however, had significantly more myelinated axons than females. Thus, sex differences in axon density in the adult rat splenium were regional and did not result in overall sex differences in axon number.

Animals↗
PubMed1978

Androgen-mediated sex differences of cardiovascular responses in rats.

Sex differences in the systemic depressor response to arachidonic acid (50 or 150 microgram/kg iv) were observed in intact and castrated anesthetized Sprague-Dawley rats. The rank order of responsiveness was: castrate males, castrate females, females, males; all four groups were significantly different (P less than 0.05) at the higher dose. Castrated males pretreated with testosterone (1 mg/kg sc) 5 or 7 days previously gave a response at the higher arachidonate dose levels that was of the same order as that obtained with intact males. Similar treatment of castrate males with androgen potentiated (P less than 0.05) the vasopressor action of norepinephrine (0.25 microgram/kg) on day 7 after the testosterone pretreatment. In contrast, treatment with depot estradiol (100 microgram/kg sc) in castrate males produced no significant change in the response to either of the vasoactive compounds on both days 5 and 7 after pretreatment. These data suggest that testosterone may be a significant factor in the development of sex differences in the cardiovascular systems of rats.

Androgens↗