Sex Differences and Individual Differences in Cognitive Performance and Their Relationship to Endogenous Gonadal Hormones and Gonadotropins

Neurobiological characteristics associated with gender identity: Findings from neuroimaging studies in the Amsterdam cohort of children and adolescents experiencing gender incongruence

This review has been based on my invited lecture at the annual meeting of the Society for Behavioral Neuroendocrinology in 2023. Gender incongruence is defined as a marked and persistent incongruence between an individual's experienced gender and the sex assigned at birth. A prominent hypothesis on the etiology of gender incongruence proposes that it is related to an altered or less pronounced sexual differentiation of the brain. This hypothesis has primarily been based on postmortem studies of the hypothalamus in transgender individuals. To further address this hypothesis, a series of structural and functional neuroimaging studies were conducted in the Amsterdam cohort of children and adolescents experiencing gender incongruence. Additional research objectives were to determine whether any sex and gender differences are established before or after puberty, as well as whether gender affirming hormone treatment would affect brain development and function. We found some evidence in favor of the sexual differentiation hypothesis at the functional level, but this was less evident at the structural level. We also observed some specific transgender neural signatures, suggesting that they might present a unique brain phenotype rather than being shifted towards either end of the male-female spectrum. Our results further suggest that the years between childhood and mid-adolescence represent an important period in which puberty-related factors influence several neural characteristics, such as white matter development and functional connectivity patterns, in both a sex and gender identity specific way. These latter observations thus lead to the important question about the possible negative consequences of delaying puberty on neurodevelopment. To further address this question, larger-scale, longitudinal studies are required to increase our understanding of the possible neurodevelopmental impacts of delaying puberty in transgender youth.

Attentional, anticipatory and spatial cognition fluctuate throughout the menstrual cycle: Potential implications for female sport

Current research suggests that menstruating female athletes might be at greater risk of musculoskeletal injury in relation to hormonal changes throughout the menstrual cycle. A separate body of work suggests that spatial cognition might also fluctuate in a similar manner. Changes in spatial cognition could, in theory, be a contributing risk factor for injury, especially in fast-paced sports that require precise, millisecond accuracy in interactions with moving objects in the environment. However, existing theories surrounding causes for increased injury risk in menstruating females largely focus on biomechanical mechanisms, with little consideration of possible cognitive determinants of injury risk. Therefore, the aim of this proof-of-principle study was to explore whether menstruating females exhibit fluctuations in cognitive processes throughout their cycle on a novel sport-oriented cognitive test battery, designed to measure some of the mental processes putatively involved in these sporting situations. A total of 394 participants completed an online cognitive battery, a mood scale and a symptom questionnaire twice, 14 days apart. After exclusions, 248 eligible participants were included in the analyses (mean: 28 ± 6 years) (male = 96, female(menstruating) = 105, female(contraception) = 47). Cycle phase for menstruating females was based on self-reported information. The cognitive battery was designed to measure reaction times, attention, visuospatial functions (including 3D mental rotation) and timing anticipation. Three composite scores were generated using factor analysis with varimax rotation (Errors, Reaction Time, Intra-Individual Variability). Mixed model ANOVAs and repeated measures ANOVAs were performed to test for between and within-subject effects. There was no group difference in reaction times and accuracy between males and females (using contraception and not). However, within subject analyses revealed that regularly menstruating females performed better during menstruation compared to being in any other phase, with faster reaction times (10ms c.ca, p < 0.01), fewer errors (p < 0.05) and lower dispersion intra-individual variability (p < 0.05). In contrast they exhibited slower reaction times (10ms c.ca, p < 0.01) and poorer timing anticipation (p < 0.01) in the luteal phase, and more errors in the predicted ovulatory phase (p < 0.01). Self-reported mood, cognitive and physical symptoms were all worst during menstruation (p < 0.01), and a significant proportion of females felt that their symptoms were negatively affecting their cognitive performance during menstruation on testing day, which was incongruent with their actual performance. These findings suggest that visuospatial and anticipatory processes may fluctuate throughout the menstrual cycle in the general population, with better performance during the menstrual phase and poorer performance during the luteal phase. If these extend to associations between phase-specific cognitive performance and injury incidence, they would support a cognitive theory of determinants of injury risk in cycling female athletes, opening an opportunity to develop mitigation strategies where appropriate.

The Influence of Kapalabhati on Working Memory and Phasic Heart Rate Variability

BACKGROUND

Cognitive communication abilities, such as working memory (WM), are vital for accomplishing daily activities and are also important for higher-order processes such as planning and problem-solving. The current study investigates the simultaneous effect of kapalabhati (KBH) on WM and phasic heart rate variability (HRV).

METHODS

Twenty participants who fulfilled the inclusion and exclusion criteria, with an average age of 23.65±3.07 years (mean±SD), were recruited for the study. Prior to data collection, the participants underwent a seven-day orientation to maintain uniformity in KBH practice. EKGs were assessed using a 16-channel polygraph system arranged in a standard limb lead II configuration. WM was assessed using E-Prime version 2.0 (Psychology Software Tools, Sharpsburg, PA, USA).

RESULTS

There was a significant increase in accuracy after the immediate KBH practice in all three conditions of the WM task (i.e., n-back task: 0-back, 1-back, and 2-back). However, there was also an increase in reaction time. Repeated measures ANOVA of HRV measures showed statistically significant changes in mean rhythm-to-rhythm (RR) intervals, heart rate (HR), number of adjacent N-N intervals over 50 milliseconds (NN50), percentage of successive normal sinus RR intervals greater than 50 milliseconds (pNN50 RR), low frequency (LF), and high frequency (HF), with HR, NN50, pNN50, LF, and HF all significant at p<0.001 and the LF/HF ratio significant at the p<0.01 level.

CONCLUSION

The results of the current study suggest that KBH practice can modulate vagal tone or parasympathetic activity and improve WM performance. Furthermore, the parasympathetic shift found in the present study may promote better cardioprotective health and longevity.

Brain-based sex differences in schizophrenia: A systematic review of fMRI studies

Schizophrenia is a chronic psychiatric disorder with characteristic symptoms of delusions, hallucinations, lack of motivation, and paucity of thought. Recent evidence suggests that the symptoms of schizophrenia, negative symptoms in particular, vary widely between the sexes and that symptom onset is earlier in males. A better understanding of sex-based differences in functional magnetic resonance imaging (fMRI) studies of schizophrenia may provide a key to understanding sex-based symptom differences. This study aimed to summarize sex-based functional magnetic resonance imaging (fMRI) differences in brain activity of patients with schizophrenia. We searched PubMed and Scopus to find fMRI studies that assessed sex-based differences in the brain activity of patients with schizophrenia. We excluded studies that did not evaluate brain activity using fMRI, did not evaluate sex differences, and were nonhuman or in vitro studies. We found 12 studies that met the inclusion criteria for the current systematic review. Compared to females with schizophrenia, males with schizophrenia showed more blood oxygen level-dependent (BOLD) activation in the cerebellum, the temporal gyrus, and the right precuneus cortex. Male patients also had greater occurrence of low-frequency fluctuations in cerebral blood flow in frontal and parietal lobes and the insular cortex, while female patients had greater occurrence of low-frequency fluctuations in the hippocampus, parahippocampus, and lentiform nucleus. The current study summarizes fMRI studies that evaluated sex-based fMRI brain differences in schizophrenia that may help to shed light on the underlying pathophysiology and further understanding of sex-based differences in the clinical presentation and course of the disorder.

Visuospatial Function in Women with Premenstrual Dysphoric Disorder

Background/Objectives: Premenstrual dysphoric disorder (PMDD) is an understudied psychiatric condition affecting reproductive-age women who experience negative mood in the luteal phase of the menstrual cycle. Cognitive functions in PMDD are not well understood as patients have been tested in the luteal phase. This may confound study results due to noted emotional interferences, as well as the potential opposing effects of the sex hormones estradiol and progesterone. In the present study, we evaluated visuospatial function in the follicular phase in women with PMDD and healthy controls, and further examined the effect of estradiol as research into the hormonal mediation of visuospatial function in reproductive-age women has produced mixed results. Methods: To this end, we analyzed estradiol concentrations using the gold standard mass spectrometry. Serum samples were collected in the early follicular and mid/late follicular subphases when estradiol is low and high, respectively, while progesterone is low and steady. We assessed visuospatial function using the classic mental rotation task. Results: Women with PMDD had a higher mental rotation total score (t = 2.17; p < 0.05). The addition of six demographic, biological, and anthropomorphic variables in a hierarchical fashion accounted for 45.3% of the total variance in the final model with diagnosis remaining statistically significant (t = 4.36; p < 0.001). Estradiol did not mediate the group difference and was not significantly associated with visuospatial function. Conclusions: The present results provide support for new research directions into the potential biological mechanisms that underlie the pathophysiology of PMDD, represented as enhanced visuospatial ability in women with PMDD in the follicular phase. We review the theory that PMDD is a disorder of the enhanced excitation-to-inhibition ratio, with a focus on findings to date from brain imaging research.

The role of sex hormones, oral contraceptive use, and its parameters on visuospatial abilities, verbal fluency, and verbal memory

Sex hormones can cross the blood-brain barrier and access brain regions underlying higher-order cognition. Containing synthetic sex hormones, oral contraceptives (OC) have been found to modulate visuospatial and verbal abilities, though inconsistencies have been found in the literature. Among possible explanations, certain OC use parameters (progestin androgenicity, synthetic hormone levels, duration of use) have not received consistent consideration. Thus, the objectives were to (1) examine group differences between men, combined OC users, and naturally cycling women (NC women; not using OC) in visuospatial abilities, verbal fluency, and verbal memory and (2) investigate the contribution of endogenous and exogenous sex hormones on these effects. We also aimed to (3) identify OC use parameters relevant to cognitive outcomes. In total, 70 combined OC users, 53 early follicular (EF) women, 43 pre-ovulatory (PO) women, and 47 men underwent cognitive tests. Performance was compared based on hormonal milieus (OC, EF, PO, men) and OC users' contraceptive androgenicity (anti, low, high). Correlations between performance, hormone levels and OC use duration were also conducted. OC use dampened the sex difference that typically favors men in 3D visuospatial abilities, whereas its duration of use positively predicted verbal fluency. Androgenicity and hormone levels did not predict performance in any task. These results highlight the importance of considering OC use duration. Results also did not support a role for androgenicity in cognition. Importantly, combined OC use (including prolonged use) does not impair visuospatial, verbal, and memory functions in a healthy young sample.

Change in auditory and visuospatial working memory with phases of menstrual cycle: A prospective study of three consecutive cycles

The menstrual cycle is a well-known physiological model used to study working memory (WM) function. The present study examined auditory and visuospatial WM during proliferative and secretory phases of three consecutive menstrual cycles.Forty young adult females with a mean age of 23.4 ± 4.2 years and a history of regular menstrual cycle were selected for this study. Computerized software-based dual-task n-back WM tasks were performed by each participant during the proliferative (day 10th - 14th) and secretory phases (day 21st - 25th) of the menstrual cycle. The above tasks were repeated for three consecutive menstrual cycles during follow-up.Data from the three menstrual cycles were pooled and compared between the proliferative and secretory phases. Significant differences were observed in the hit rate (p = 0.006), Z score (p = 0.004) and parametric sensitivity (p = 0.005) of visuospatial targets and Z score (p = 0.037) and parametric sensitivity (p = 0.028) of auditory targets with better performance during the secretory phase. However, no significant differences were found across the three proliferative or three secretory phases, indicating that the results were consistent across consecutive cycles.This study concluded that visuospatial and auditory WM skills were significantly improved during the secretory phase compared to the proliferative phase of the menstrual cycle.

Sex/Gender Differences in Verbal Fluency and Verbal-Episodic Memory: A Meta-Analysis

Women are thought to fare better in verbal abilities, especially in verbal-fluency and verbal-memory tasks. However, the last meta-analysis on sex/gender differences in verbal fluency dates from 1988. Although verbal memory has only recently been investigated meta-analytically, a comprehensive meta-analysis is lacking that focuses on verbal memory as it is typically assessed, for example, in neuropsychological settings. On the basis of 496 effect sizes and 355,173 participants, in the current meta-analysis, we found that women/girls outperformed men/boys in phonemic fluency (ds = 0.12-0.13) but not in semantic fluency (ds = 0.01-0.02), for which the sex/gender difference appeared to be category-dependent. Women/girls also outperformed men/boys in recall (d = 0.28) and recognition (ds = 0.12-0.17). Although effect sizes are small, the female advantage was relatively stable over the past 50 years and across lifetime. Published articles reported stronger female advantages than unpublished studies, and first authors reported better performance for members of their own sex/gender. We conclude that a small female advantage in phonemic fluency, recall, and recognition exists and is partly subject to publication bias. Considerable variance suggests further contributing factors, such as participants' language and country/region.

Latent structure of cognitive tests is invariant in men and women with schizophrenia

Studies comparing the cognitive functioning of men and women with schizophrenia have produced conflicting results which could arise from sex-based differences in the latent structure of cognitive abilities. The current study used multigroup confirmatory factor analysis to examine invariance in latent structure of cognitive abilities to between men and women with schizophrenia. Confirmatory factor analysis of an initial neurocognitive assessment (men n = 612, women n = 201) and cross-validation using second assessment (men n = 549, women n = 198) demonstrated that a bifactor seven-factor model fit the data best for both men and women. Invariance analyses further indicated this model was invariant across men and women at both assessments. Group comparisons indicated women had significantly higher scores for Semantic Memory, Verbal Memory, and General Cognitive factors, whereas men exhibited better performance on the Vigilance factor. Results indicate that cognition in SZ is characterized by both a general cognitive factor and specific domains for both men and women. Invariance analysis provides evidence that cognitive differences between men and women do not result from sex-based differences in the latent structure of cognitive abilities. Current results also indicate small but statistically significant neurocognitive differences between men and women with schizophrenia.

Sexual dimorphism in immune cell responses following stroke

Recent bodies of work in regard to stroke have revealed significant sex differences in terms of risk and outcome. While differences in sex hormones have been the focus of earlier research, the reasons for these differences are much more complex and require further identification. This review covers differences in sex related immune responses with a focus on differences in immune cell composition and function. While females are more susceptible to immune related diseases, they seem to have better outcomes from stroke at the experimental level with reduced pro-inflammatory responses. However, at the clinical level, the picture is much more complex with worse neurological outcomes from stroke. While the use of exogenous sex steroids can replicate some of these findings, it is apparent that many other factors are involved in the modulation of immune responses. As a result, more research is needed to better understand these differences and identify appropriate interventions and risk modification.

Effects of hCG on DA neuronal death of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, with the incidence in men being about twice as compared to women. Gender differences may provide clues for finding key targets that mediate the death of dopaminergic (DA) neurons in PD. Luteinizing hormone (LH), analog of human chorionic gonadotropin (hCG), and their receptor, luteinizing hormone/choriogonadotropin receptor (LHCGR), are associated with the pathogenesis of PD. Movement-related symptoms are partially improved by hCG in PD patients. However, the relationship between hCG and PD, as well as its roles in mediating DA neuronal death, has not been elucidated. In this study, we investigated the potential of hCG as a treatment during PD progression. After establishment of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse models, we found that hCG restored the decrease of LHCGR activity caused by down-regulation of LH in the substantia nigra. Furthermore, the reduction of LHCGR activity led to DA neuronal death through knocking down the LHCGR in DA neurons by AAV-mTH-shRNA. Treatment with hCG alleviated the DA neuronal death induced by MPTP. Finally, hCG exerted neuroprotective effects by inhibiting the activation of glycogen synthase kinase 3 beta (GSK3β) in our MPTP-induced PD mouse and MPP⁺-treated SH-SY5Y cell models. Together, these results demonstrate that hCG exerts neuroprotective effects for PD through LHCGR, and the inhibition of GSK3β activation is involved in this protective effect, suggesting that hCG can be taken as a potential therapeutic for the treatment of PD.

Testosterone and estradiol affect adolescent reinforcement learning

During adolescence, gonadal hormones influence brain maturation and behavior. The impact of 17β-estradiol and testosterone on reinforcement learning was previously investigated in adults, but studies with adolescents are rare. We tested 89 German male and female adolescents (mean age ± sd = 14.7 ± 1.9 years) to determine the extent 17β-estradiol and testosterone influenced reinforcement learning capacity in a response time adjustment task. Our data showed, that 17β-estradiol correlated with an enhanced ability to speed up responses for reward in both sexes, while the ability to wait for higher reward correlated with testosterone primary in males. This suggests that individual differences in reinforcement learning may be associated with variations in these hormones during adolescence, which may shift the balance between a more reward- and an avoidance-oriented learning style.

The role of steroid hormones in the sexual differentiation of the human brain

Widespread sex differences in human brain structure and function have been reported. Research on animal models has demonstrated that sex differences in brain and behavior are induced by steroid hormones during specific, hormone sensitive, developmental periods. It was shown that typical male neural and behavioral characteristics develop under the influence of testosterone, mostly acting during perinatal development. By contrast, typical female neural and behavioral characteristics may actually develop under the influence of estradiol during a specific prepubertal period. This review provides an overview of our current knowledge on the role of steroid hormones in the sexual differentiation of the human brain. Both clinical and neuroimaging data obtained in patients with altered androgen levels/actions (i.e., congenital adrenal hyperplasia or complete androgen insensitivity syndrome [CAIS]), point to an important role of (prenatal) androgens in inducing typical male neural and psychosexual characteristics in humans. In contrast to rodents, there appears to be no obvious role for estrogens in masculinizing the human brain. Furthermore, data from CAIS also suggest a contribution of sex chromosome genes to the development of the human brain. The final part of this review is dedicated to a brief discussion of gender incongruence, also known as gender dysphoria, which has been associated with an altered or less pronounced sexual differentiation of the brain.

The influence of estradiol and progesterone on neurocognition during three phases of the menstrual cycle: Modulating factors

Estradiol is an ovarian steroid hormone that peaks shortly before ovulation and significantly affects various brain regions and neurotransmitter systems, with similar and differential effects with progesterone, another ovarian hormone. Studies investigating the neurocognitive processes during the menstrual cycle have focused on the early follicular phase (EFP) characterized by low estradiol and progesterone levels and the mid-luteal phase (MLP) with high estradiol and progesterone levels. However, most studies have failed to include the ovulatory phase, characterized by high estradiol and low progesterone levels. Given the various hormonal changes in the menstrual cycle, we revisited studies suggesting that the menstrual cycle did not affect verbal and spatial abilities and observed that many contain mixed results. Comparing these studies makes it possible to identify relevant modulating factors, such as sample size, participant age, accurate selection of days for testing, asymmetrical practice effects, genetic polymorphisms, and task difficulty. More robust findings are related to improved mental rotation capacity during EFP with challenging tasks and differences in brain activation among menstrual cycle phases during the execution of spatial and verbal tasks. During MLP, less robust findings were observed, possibly modulated by the complex effects of the two hormones on the brain. In conclusion, we propose that it is crucial to include all three menstrual cycle phases and consider these modulating factors to avoid confounding findings.

Sex differences in neurocognitive and psychosocial functioning in bipolar disorder

BACKGROUND

Sex differences influence the clinical characteristics and course of illness of bipolar disorder (BD).

OBJECTIVE

Therefore, the aim of the present study was to examine the role of sex differences in neurocognitive performance and psychosocial functioning in a large sample of euthymic patients suffering from BD.

METHODS

The sample included 462 individuals, 347 patients with BD (148 males and 199 females) and 115 healthy controls (HC) (45 males and 70 females). Performance on a comprehensive neuropsychological battery assessing six cognitive domains and psychosocial functioning was compared between groups using linear mixed models, with sex and group as main effects, group by sex interactions and center as a random effect.

RESULTS

Males performed better than females in working memory (p < 0.001), whereas females outperformed males in the verbal learning (p = 0.03) and memory recognition (p = 0.03) tasks. No significant group by sex interactions were detected in cognitive performance. There were no overall sex differences or group by sex interactions in psychosocial functioning.

LIMITATIONS

Lack of assessment of visuo-spatial working memory.

CONCLUSIONS

There were no overall sex differences in neurocognition and psychosocial functioning. However, small sex differences in some measures of working memory and verbal memory were found. Individual differences of each patient, including sex perspective, should be considered in order to perform a tailored intervention plan adjusted to specific needs in the context of personalized treatment.

Exploring the sex and gender correlates of cognitive sex differences

The correlates of cognitive sex differences are yet to be fully understood. Many biological and psychosocial factors modulate these cognitive abilities leading to mixed results in the scientific literature. The current study aims to explore the different parameters potentially influencing cognitive abilities acting in synergy. Sex and gender correlates of cognitive functioning were assessed in a sample of individuals ages 18 to 45 years (N = 87) from diverse sexual orientations. Sex hormones were assessed via saliva samples at four timepoints throughout the testing. Gender roles, sexual orientation and socio-demographics were measured via self-report questionnaires. Participants completed mental rotation and verbal fluency tasks. Men performed better than women at mental rotation, while no significant difference was found for verbal fluency. Significant positive associations were observed between estradiol and word fluency for the naturally cycling women compared to the women using oral contraception. While controlling for sex hormones, a significant interaction effect of sex by gender roles was identified for mental rotation among masculine women. These exploratory results suggest an effect principally driven by sex and sex hormones on cognitive performance that will need to be furthered with larger studies.

Autism spectrum disorder: An examination of sex differences in neuropsychological and self-report measures of executive and non-executive cognitive function

LAY ABSTRACT

Research comparing females and males with a diagnosis of autism suggests that there are sex differences in some characteristics such as behaviour regulation. One area not studied in detail is whether females and males with autism perform differently in tests of cognitive ability. The results of previous research are quite mixed. One explanation may be that some research comparing females and males with autism did not include a neurotypical control group for comparison. As a result, it is not clear whether the sex differences in cognitive ability observed in people with autism are similar to differences between neurotypical males and females. To better understand whether there are unique differences between males and females with autism, it is important to also compare them with neurotypical males and females. In our research, we included a neurotypical group and compared males and females with and without a diagnosis of autism. We found that the sex differences in autism are similar to what we observe in males and females without autism. Our study showed that compared with males, females (with and without autism) do better in assessments of processing speed, cognitive flexibility, verbal learning and memory and semantic fluency. Our results suggest that although females show different cognitive performance to males, these sex differences were not specific to the group with a diagnosis of autism.

Cognitive function in association with high estradiol levels resulting from fertility treatment

The putative association between hormones and cognitive performance is controversial. While there is evidence that estradiol plays a neuroprotective role, hormone treatment has not been shown to improve cognitive performance. Current research is flawed by the evaluation of combined hormonal effects throughout the menstrual cycle or in the menopausal transition. The stimulation phase of a fertility treatment offers a unique model to study the effect of estradiol on cognitive function. This quasi-experimental observational study is based on data from 44 women receiving IVF in Zurich, Switzerland. We assessed visuospatial working memory, attention, cognitive bias, and hormone levels at the beginning and at the end of the stimulation phase of ovarian superstimulation as part of a fertility treatment. In addition to inter-individual differences, we examined intra-individual change over time (within-subject effects). The substantial increases in estradiol levels resulting from fertility treatment did not relate to any considerable change in cognitive functioning. As the tests applied represent a broad variety of cognitive functions on different levels of complexity and with various brain regions involved, we can conclude that estradiol does not show a significant short-term effect on cognitive function.

Eye-movements during number comparison: Associations to sex and sex hormones

Multi-digit numbers are of a hierarchical nature with whole number magnitudes depending on digit magnitudes. Processing of multi-digit numbers can occur in a holistic or decomposed fashion. The unit-decade compatibility effect during number comparison is often used as a measure of decomposed processing. It refers to the fact that performance is reduced when the larger number contains the smaller unit digit (e.g. 73 vs. 26). It has been demonstrated that women show a larger compatibility effect than men, which is in accordance with their general tendency towards focusing on stimulus details during processing of visual hierarchical stimuli (local processing style). Such a local processing style has been related to higher progesterone and lower testosterone levels. One method to study individual processing styles is eye-tracking. The aim of the present study was to examine whether sex and sex hormones (estradiol, progesterone, testosterone) relate to eye movement behavior in the number comparison task. Unlike previous studies we found no evidence for sex differences in the behavioral compatibility effect. Nevertheless, women look more often and longer at individual digits and show a stronger compatibility effect in fixation durations compared to men, while men show more saccades between numbers than women. Estradiol and progesterone were related to fewer fixations and shorter fixation durations and more saccades between numbers in men, but not in women. Furthermore, the compatibility effect in the number of fixations and fixation durations was negatively related to testosterone in women. In summary, this is the first study to demonstrate sex differences and sex hormone influences on eye gaze behavior during number comparison.

The Role of Endocrine Stress Systems and Sex Hormones in the Enhancing Effects of Stress on Mental Rotation Capabilities

The possible effects of stress and neurobiological stress mechanisms on visuospatial abilities remain largely unknown. In the current study, we examined the combined effect of sex hormones and both the hypothalamic–pituitary–adrenal axis (HPA-A) and the sympathetic nervous system (SNS) on stress-induced changes in visuospatial performance. A total of 107 participants completed a mental rotation task and were subsequently exposed to either to the Trier social stress test (TSST) or to a control condition before completing the mental rotation task again. HPA-A and SNS reactivity of the participants were evaluated by measuring salivary alpha amylase (sAA; an SNS activation marker) and cortisol in four saliva samples. Pre-stress levels of sex hormones (progesterone, estradiol, and testosterone) were also measured. The TSST enhanced mental rotation performance, and this enhancement was negatively correlated with baseline estradiol levels and positively correlated with the level of cortisol reactivity among men. In addition, controlling for baseline levels of testosterone, estradiol, and progesterone diminished this effect of stress. These results imply that the stress-induced facilitation of mental rotation performance is modulated by baseline sex hormones and provide preliminary support to the notion that a complex interaction between sex hormones and neuroendocrine stress mechanisms mediates the influence of stress on visuospatial performance.

Interactive role of endocrine stress systems and reproductive hormones in the effects of stress on declarative memory

The effects of stress on memory performance, and the neuroendocrine mechanisms mediating such effects, are not well understood. Given the interrelationship between reproductive hormones and both the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal axis (HPA-A), we examined their combined effect on stress-induced modulation of declarative memory. Before and after exposure either to the Trier Social Stress Test (TSST) procedure or to a non-stress condition, 112 participants completed the Rey Auditory Verbal Learning Test. We analyzed participants' HPA-A and SNS reactivity by measuring cortisol and salivary alpha-amylase (sAA, an SNS activation marker) in four saliva samples. In addition, testosterone, estradiol, and progesterone were sampled prior to the stress exposure. Exposure to the TSST attenuated memory recall after an introduction of an interference list during the declarative memory task. Importantly, controlling for testosterone, estradiol, and progesterone diminished this effect of stress, suggesting the importance of baseline reproductive hormones in stress-induced modulation of memory functions. Furthermore, a multiple regression model revealed that stress-induced declines in memory performance were negatively associated with participants' stress-induced cortisol reactivity, but only among individuals with high testosterone levels. In addition, stress-induced declines in memory performance were negatively associated with participants' stress-induced increases in sAA, but only in individuals with low progesterone levels. These findings suggest that the effects of stress on memory performance may be modulated by baseline reproductive hormones and provide a preliminary indication for specific modulatory interrelationships between reproductive hormones and neuroendocrine stress mechanisms in mediating the effects of stress on memory.

Influence of sex, menstrual cycle, and hormonal contraceptives on egocentric navigation with or without landmarks

This study examines the influence of sex, menstrual cycle, hormonal contraceptives (HC) and sex hormone levels in following egocentric navigation instructions with or without landmarks. Estradiol seem to bias the reference frame for navigation during estrous cycle of female rats. However, previous studies in humans found no differences in overall navigation between women in their early follicular and mid-luteal menstrual cycle phases, whose performance was worse than that of men. Our study hypothesis was that the performance of women would be improved during the peri-ovulatory phase and would remain the same during placebo and active phases of HC users. The study included 21 men, 62 women with natural menstrual cycle (21 during early follicular phase, 20 during peri-ovulatory phase, and 21 during mid-luteal phase), and 38 women that were receiving HC (13 during placebo phase and 25 during active phase). The men outperformed the women with a natural menstrual cycle when following egocentric instructions without landmarks. However, the women's performance varied according to the phase of their menstrual cycle, differing from men during early follicular and mid-luteal phases but not during the peri-ovulatory phase. The use of HC also improved the performance of women to the extent that the difference with men disappeared. No differences were observed between HC-placebo and HC-active user groups during egocentric navigation without landmarks and among all groups during egocentric navigation with landmarks. Analysis of salivary hormones showed that testosterone levels were higher in men and that estradiol levels in women were higher during peri-ovulatory and mid-luteal phases and also in HC users. Progesterone levels were higher in women during the mid-luteal phase. These results appear compatible with beneficial effect of testosterone and estradiol on egocentric navigation without landmarks and with a block of this effect produced by progesterone.

A systematic review and meta-analysis of behavioural sex differences in executive control

Literature investigating whether an individuals' sex affects their executive control abilities and performance on cognitive tasks in a normative population has been contradictory and inconclusive. Using meta-analytic procedures (abiding by PRISMA guidelines), this study attempts to identify the magnitude of behavioural sex differences in three prominent executive control domains of cognitive set-shifting, performance monitoring, and response inhibition. PubMed, Web of Science, and Scopus were systematically searched. Across 46 included studies, a total of 1988 females and 1884 males were included in the analysis. Overall, males and females did not differ on performance in any of the three domains of performance monitoring, response inhibition, or cognitive set-shifting. Task-specific sex differences were observed in the domains of performance monitoring, in the CANTAB Spatial Working Memory task-males scored statistically higher than females (Hedges' g = -0.60), and response inhibition, in the Delay Discounting task-females scored statistically higher than males (Hedges' g = 0.64). While the meta-analysis did not detect overall behavioural sex differences in executive control, significant heterogeneity and task-specific sex differences were found. To further understand sex differences within these specific tasks and domains, future research must better control for age and sex hormone levels.

Sex Differences in Cognitive Functioning in At-Risk Mental State for Psychosis, First Episode Psychosis and Healthy Control Subjects

Background:

Several sex differences in schizophrenia have been reported including differences in cognitive functioning. Studies with schizophrenia patients and healthy controls (HC) indicate that the sex advantage for women in verbal domains is also present in schizophrenia patients. However, findings have been inconsistent. No study focused on sex-related cognitive performance differences in at-risk mental state for psychosis (ARMS) individuals yet. Thus, the aim of the present study was to investigate sex differences in cognitive functioning in ARMS, first episode psychosis (FEP) and HC subjects. We expected a better verbal learning and memory performance of women in all groups.

Methods:

The neuropsychological data analysed in this study were collected within the prospective Früherkennung von Psychosen (FePsy) study. In total, 118 ARMS, 88 FEP individuals and 86 HC completed a cognitive test battery covering the domains of executive functions, attention, working memory, verbal learning and memory, IQ and speed of processing.

Results:

Women performed better in verbal learning and memory regardless of diagnostic group. By contrast, men as compared to women showed a shorter reaction time during the working memory task across all groups.

Conclusion:

The results provide evidence that women generally perform better in verbal learning and memory, independent of diagnostic group (ARMS, FEP, HC). The finding of a shorter reaction time for men in the working memory task could indicate that men have a superior working memory performance since they responded faster during the target trials, while maintaining a comparable overall working memory performance level.

Cognition, The Menstrual Cycle, and Premenstrual Disorders: A Review

Sex hormones, such as estrogens, progesterone, and testosterone, have a significant influence on brain, behavior, and cognitive functioning. The menstrual cycle has been a convenient model to examine how subtle fluctuations of these hormones can relate to emotional and cognitive functioning. The aim of the current paper is to provide a narrative review of studies investigating cognitive functioning in association with the menstrual cycle in biological females, with a focus on studies that have investigated cognitive functioning across the menstrual cycle in females with premenstrual mood disorders, such as premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). In line with previous reviews, the current review concluded that there is a lack of consistent findings regarding cognitive functioning across the menstrual cycle. Most studies focused on changes in levels of blood estrogen, and neglected to explore the role of other hormones, such as progesterone, on cognitive functioning. Cognitive research involving premenstrual disorders is in its infancy, and it remains unclear whether any cognitive disturbances that are identified may be attributed to negative experience of mood and psychological symptoms or be a more direct effect of hormonal dysregulation or sensitivity. Suggestions for future research are provided.

Gender stereotypes and incremental beliefs in STEM and non-STEM students in three countries: relationships with performance in cognitive tasks

Women's underrepresentation in science, technology, engineering and mathematics (STEM) has been linked, among others, to gender stereotypes and ability-related beliefs as well as gender differences in specific cognitive abilities. However, the bulk of studies focused on gender stereotypes related to mathematics. The present study, therefore, aimed to map gender stereotypes and incremental beliefs (i.e., the conviction about modifiability) with respect to a wide range of stereotypical male-favouring and female-favouring abilities. Gender stereotypes and incremental beliefs were assessed with self-report questionnaires in 132 STEM students (65 women) and 124 non-STEM students (73 women) in three European countries ranked in the top, middle, and bottom of the Global Gender Gap Report. Moreover, a mental rotation and a verbal fluency test were completed. Men endorsed male-favouring stereotypes more than women, and women endorsed female-favouring stereotypes more than men, an effect that was most pronounced in the country with the larger gender gap. Male STEM students endorsed male-favouring stereotypes more strongly than male non-STEM and female STEM students. Male non-STEM students endorsed female-favouring stereotypes less than female and male STEM students. Female STEM students reported higher incremental beliefs than female non-STEM students, especially in the country with the lowest gender gap. Men outperformed women, and STEM students outperformed non-STEM in mental rotation, while women outperformed men in verbal fluency. Male STEM students' stronger endorsement of male-favouring stereotypes might reflect genuine group differences, at least in mental rotation. While potentially such gender stereotypes can help creating a "chilly climate" where women in academic STEM degrees are expected to perform poorly, those women believed more in the possibility to change and improve in male-favouring abilities which could help them to overcome the potential negative effect of stereotyping.

Mental rotation of sequentially presented 3D figures: sex and sex hormones related differences in behavioural and ERP measures

Mental rotation of 3D objects demonstrates one of the largest sex differences. We investigated sex and sex hormones-related differences in behaviour and event related potentials (ERP) using a modified Shepard and Metzler task composed of sequentially presented 3D figures in 29 men and 32 women. We demonstrated a significant increase in response time and decrease in both accuracy and positivity of the parietal ERP with increasing angular disparity between the figures. Higher angular disparity evoked an increase of global field power (GFP) from 270 to 460 ms and different activation topographies from 470 to 583 ms with lower parietal, but higher left frontal positivity. Flatter slopes in higher angular disparity condition suggest distinct strategies being implemented depending on the difficulty of the rotation. Men performed the task more accurately than women. Performance accuracy in women tended to be negatively related to estradiol while the response time tended to increase with increasing progesterone. There were no associations with testosterone. Women demonstrated higher GFP and an increased positivity over the parietal scalp area, while men showed higher activation in the left frontal cortex. Together these findings indicate dynamic angular disparity- and sex-related differences in brain activity during mental rotation of 3D figures.

Sex differences in traumatic brain injury: a multi-dimensional exploration in genes, hormones, cells, individuals, and society

Traumatic brain injury (TBI) is exceptionally prevalent in society and often imposes a massive burden on patients' families and poor prognosis. The evidence reviewed here suggests that gender can influence clinical outcomes of TBI in many aspects, ranges from patients' mortality and short-term outcome to their long-term outcome, as well as the incidence of cognitive impairment. We mainly focused on the causes and mechanisms underlying the differences between male and female after TBI, from both biological and sociological views. As it turns out that multiple factors contribute to the gender differences after TBI, not merely the perspective of gender and sex hormones. Centered on this, we discussed how female steroid hormones exert neuroprotective effects through the anti-inflammatory and antioxidant mechanism, along with the cognitive impairment and the social integration problems it caused. As to the treatment, both instant and long-term treatment of TBI requires adjustments according to gender. A further study with more focus on this topic is therefore suggested to provide better treatment options for these patients.

Beyond Biological Sex: Interactive Effects of Gender Role and Sex Hormones on Spatial Abilities

Sex differences in spatial abilities are well documented, even though their underlying causes are poorly understood. Some studies assume a biological basis of these differences and study the relationship of sex hormone levels to spatial abilities. Other studies assume social influences and study the relationship of gender role (masculinity/femininity) to spatial abilities. Contemporary theories postulate a psychobiosocial model of sex differences in spatial abilities, in which both biological (e.g., hormonal) and psychosocial (e.g., gender role) variables interactively modulate spatial abilities. However, few studies have addressed both aspects simultaneously. Accordingly, the present study explores potential interactive effects between gender role and sex hormones on spatial performance. 41 men and 41 women completed a mental rotation and a virtual navigation task. Sex hormone levels and gender role were assessed in all participants. Sex differences favoring men were observed in both tasks. We found that neither sex hormones nor gender role alone emerged as mediators of these sex differences. However, several interactive effects between gender role and sex hormones were identified. Combined effects of masculinity and testosterone were observed for those variables that displayed sex differences. Participants with both, high masculinity and high testosterone showed the best performance. However, this association was further modulated by biological sex and progesterone levels. Furthermore, we observed an interactive effect of femininity, estradiol and testosterone on response times in both tasks. Consistent across both tasks and irrespective of biological sex, testosterone related to response times in participants with low estradiol levels, depending on their femininity. In participants with low femininity, testosterone was related to slower reaction times, while in participants with higher femininity, testosterone was related to faster reaction times.

Prenatal testosterone does not explain sex differences in spatial ability

The most consistent sex differences in cognition are found for spatial ability, in which males, on average, outperform females. Utilizing a twin design, two studies have shown that females with male co-twins perform better than females with female co-twins on a mental rotation task. According to the Twin Testosterone Transfer hypothesis (TTT) this advantage is due to in-uterine transmission of testosterone from males to females. The present study tested the TTT across 14 different spatial ability measures, including mental rotation tasks, in a large sample of 19–21-year-old twins. Males performed significantly better than females on all spatial tasks, with effect sizes ranging from η² = 0.02 to η² = 0.16. Females with a male co-twin outperformed females with a female co-twin in two of the tasks. The effect sizes for both differences were negligible (η² < 0.02). Contrary to the previous studies, our results gave no indication that prenatally transferred testosterone, from a male to a female twin, influences sex differences in spatial ability.

Age and Sex Differences in Verbal and Visuospatial Abilities

In order to explore the developmental patterns of sex differences in verbal and visuospatial abilities, the present study investigated sex differences in various cognitive abilities among children and adults. Three hundred and twenty-six children and adults completed a battery of six cognitive tasks testing two sets of abilities: The verbal cognitive battery tested verbal fluency and short-term memory tasks. The visuospatial battery tested mental rotation, localization, and form-completion tasks. Results showed a significant Sex × Age interaction on the mental rotation task, with men outperforming women in the 3D task, but with no sex differences shown in childhood in the 2D task. Sex differences in verbal fluency were found, with girls and women outperforming boys and men in this task. Findings are discussed within an integrative approach of biological as well as environmental factors.

Progesterone and human cognition

Progesterone is a neurosteroid and a neuroactive steroid, produced primarily by the corpus luteum and the placenta. In some animal models, progesterone affects cognitive performance, and its potential role in human cognition is especially germane to women. This role can be investigated through associations between peripheral concentrations of progesterone in blood or saliva and neuropsychological test results, through differences in cognitive profiles between women using menopausal hormone therapy with and without a progestogen, and through clinical trials. In naturally cycling reproductive-age women and pregnant women, there is no consistent relation between progesterone levels and cognition. In postmenopausal women within 6 years of menopause and not using hormone therapy, progesterone levels are positively associated with verbal memory and global cognition, but reported associations in older postmenopausal women are null. Some observational studies of postmenopausal women using hormone therapy raise concern of a small deleterious cognitive effect of progestogen (medroxyprogesterone acetate was most often reported in these studies), but this association may due to confounding factors. Small, short-term clinical trials of progesterone show no meaningful effect on cognition. The quality of evidence is low, but overall findings do not reveal consistent, clinically important effects of progesterone on cognitive function in women.

An examination of sex differences in neurocognition and social cognition in first-episode psychosis

Due to the dearth and conflicting findings of previous research, it is unclear whether males and females with first-episode psychosis (FEP) differ in their neurocognitive and social cognitive abilities. The aims of the current study were to investigate whether: (i) there are sex differences in neurocognition and social cognition among young people with FEP; and (ii) they resemble those observed in age-matched healthy controls. The current study involved secondary analysis of data from a previous study in which a large neurocognitive and social cognitive battery was administered to 146 individuals with FEP and 46 healthy controls aged 15-25 years. Seven two-way between-groups multivariate analysis of variances revealed that FEP participants were impaired relative to controls on all cognitive domains. Only one main effect of sex was found with males, regardless of group, outperforming females on verbal comprehension. A significant interaction effect was found for information processing speed with FEP females outperforming FEP males on the Symbol Digit Modalities Test; however, post-hoc analysis of the mean difference was not significant. Despite few sex differences, the current study highlights that cognitive impairment is a key feature of FEP that should be a treatment target in early intervention.

The Sexual Differentiation of the Human Brain: Role of Sex Hormones Versus Sex Chromosomes

Men and women differ, not only in their anatomy but also in their behavior. Research using animal models has convincingly shown that sex differences in the brain and behavior are induced by sex hormones during a specific, hormone-sensitive period during early development. Thus, male-typical psychosexual characteristics seem to develop under the influence of testosterone, mostly acting during early development. By contrast, female-typical psychosexual characteristics may actually be organized under the influence of estradiol during a specific prepubertal period. The sexual differentiation of the human brain also seems to proceed predominantly under the influence of sex hormones. Recent studies using magnetic resonance imaging have shown that several sexually differentiated aspects of brain structure and function are female-typical in women with complete androgen insensitivity syndrome (CAIS), who have a 46 XY karyotype but a female phenotype due to complete androgen resistance, suggesting that these sex differences most likely reflect androgen action, although feminizing effects of estrogens or female-typical socialization cannot be ruled out. By contrast, some male-typical neural characteristics were also observed in women with CAIS suggesting direct effects of sex chromosome genes in the sexual differentiation of the human brain. In conclusion, the sexual differentiation of the human brain is most likely a multifactorial process including both sex hormone and sex chromosome effects, acting in parallel or in combination.

Absence of sex differences in mental rotation performance in autism spectrum disorder

Mental rotation is one of the most investigated cognitive functions showing consistent sex differences. The 'Extreme Male Brain' hypothesis attributes the cognitive profile of individuals with autism spectrum disorder to an extreme version of the male cognitive profile. Previous investigations focused almost exclusively on males with autism spectrum disorder with only limited implications for affected females. This study is the first testing a sample of 12 female adults with high-functioning autism spectrum disorder compared to 14 males with autism spectrum disorder, 12 typically developing females and 14 typically developing males employing a computerised version of the mental rotation test. Reaction time and accuracy served as dependent variables. Their linear relationship with degree of rotation allows separation of rotational aspects of the task, indicated by slopes of the psychometric function, and non-rotational aspects, indicated by intercepts of the psychometric function. While the typical and expected sex difference for rotational task aspects was corroborated in typically developing individuals, no comparable sex difference was found in autism spectrum disorder individuals. Autism spectrum disorder and typically developing individuals did not differ in mental rotation performance. This finding does not support the extreme male brain hypothesis of autism.

Sex and menstrual cycle influences on three aspects of attention

Sex differences and menstrual cycle influences have been investigated in a variety of cognitive abilities, but results regarding attention are comparably sparse. In the present study, 35 men and 32 naturally cycling women completed three attention tasks, which are commonly used in neuropsychological assessment situations. All participants completed two sessions, which were time-locked to the follicular (low progesterone) and luteal cycle phase (high progesterone) in women. The results reveal higher operation speed during sustained attention in men, but no sex differences in selected and divided attention. Menstrual cycle influences were observed on accuracy in all three tasks. During divided and sustained attention, for which a male advantage was previously reported, accuracy was higher during the early follicular compared to the mid-luteal cycle phase. Furthermore, during selected and sustained attention the learning effect from the first to the second test session was higher in women who started the experiment in their luteal cycle phase. These results suggest a possible role of progesterone in modulating the ability to focus on certain stimulus aspects, while inhibiting others and to sustain attention over a longer period of time.

Lack of Associations between Female Hormone Levels and Visuospatial Working Memory, Divided Attention and Cognitive Bias across Two Consecutive Menstrual Cycles

Background: Interpretation of observational studies on associations between prefrontal cognitive functioning and hormone levels across the female menstrual cycle is complicated due to small sample sizes and poor replicability.

Methods: This observational multisite study comprised data of n = 88 menstruating women from Hannover, Germany, and Zurich, Switzerland, assessed during a first cycle and n = 68 re-assessed during a second cycle to rule out practice effects and false-positive chance findings. We assessed visuospatial working memory, attention, cognitive bias and hormone levels at four consecutive time-points across both cycles. In addition to inter-individual differences we examined intra-individual change over time (i.e., within-subject effects).

Results: Estrogen, progesterone and testosterone did not relate to inter-individual differences in cognitive functioning. There was a significant negative association between intra-individual change in progesterone and change in working memory from pre-ovulatory to mid-luteal phase during the first cycle, but that association did not replicate in the second cycle. Intra-individual change in testosterone related negatively to change in cognitive bias from menstrual to pre-ovulatory as well as from pre-ovulatory to mid-luteal phase in the first cycle, but these associations did not replicate in the second cycle.

Conclusions: There is no consistent association between women's hormone levels, in particular estrogen and progesterone, and attention, working memory and cognitive bias. That is, anecdotal findings observed during the first cycle did not replicate in the second cycle, suggesting that these are false-positives attributable to random variation and systematic biases such as practice effects. Due to methodological limitations, positive findings in the published literature must be interpreted with reservation.

The course of cognitive functioning after first-episode of psychosis: A six month follow-up study

Our aim with the present study was to evaluate rank-order and mean-level cognitive functioning stability among first-episode psychosis (FEP) patients, measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB), over a six month period. We also aimed to examine longitudinal measurement invariance and identify factors-such as age, gender, educational level, treatment and psychopathological change scores-potentially linked to cognitive change among patients. In addition, correlations between objectively measured and subjectively evaluated cognitive functioning were estimated. Neuropsychological assessments were administered to 85 patients after the initial stabilisation of their psychosis; 82 of the patients were retested. Subjectively perceived cognitive functioning was measured using a subscale derived from the Estonian version of the Subjective Well-Being Under Neuroleptic Scale (SWN-K-E). On average, executive functioning and processing speed improved significantly, while memory test scores decreased significantly, over time. Very high rank-order stability (r=0.80 to 0.94, p<0.001) was observed with all measured ability scores. Confirmatory factor analysis revealed the loadings of a single (broad ability) factor model were equal across both measurement occasions, but the lack of intercept invariance suggested that mean-level comparisons are more appropriately carried out at a subtest level. On average psychopathology scores and antipsychotics doses declined over time, with the latter also significantly correlating with better executive functioning. Gender was a significant moderator of some domains of cognitive performance, and decline tended to be somewhat more pronounced for women. The results also indicated the lack of any relationship between objective and subjective measurements of cognitive functioning.

Sex Differences and Menstrual Cycle Dependent Changes in Cognitive Strategies during Spatial Navigation and Verbal Fluency

Men typically outperform women in spatial navigation tasks, while the advantage of women in verbal fluency is more controversial. Sex differences in cognitive abilities have been related to sex-specific cognitive strategies on the one hand and sex hormone influences on the other hand. However, sex hormone and menstrual cycle influences on cognitive strategies have not been previously investigated. In the present study we assessed cognitive strategy use during spatial navigation and verbal fluency in 51 men and 49 women. In order to evaluate sex hormone influences, all participants completed two test sessions, which were time-locked to the early follicular (low estradiol and progesterone) and mid-luteal cycle phase (high estradiol and progesterone) in women. As hypothesized, men outperformed women in navigation, whereas women outperformed men in phonemic verbal fluency. Furthermore, women switched more often between categories in the phonemic fluency condition, compared to men, indicating sex-specific strategy use. Sex differences in strategy use during navigation did, however, not follow the expected pattern. Menstrual cycle phase, however, did modulate strategy use during navigation as expected, with improved performance with the landmark strategy in the luteal, compared to the follicular phase. No menstrual cycle effects were observed on clustering or switching during verbal fluency. This suggests a modulation of cognitive strategy use during spatial navigation, but not during verbal fluency, by relative hormone increases during the luteal phase of the menstrual cycle.

Effects of sex, menstrual cycle phase, and endogenous hormones on cognition in schizophrenia

BACKGROUND

In women with schizophrenia, cognition has been shown to be enhanced following administration of hormone therapy or oxytocin. We examined how natural hormonal changes across the menstrual cycle influence cognition in women with schizophrenia. We hypothesized that female patients would perform worse on "female-dominant" tasks (verbal memory/fluency) and better on "male-dominant" tasks (visuospatial) during the early follicular phase (low estradiol and progesterone) compared to midluteal phase (high estradiol and progesterone) in relation to estradiol but not progesterone.

METHODS

Fifty-four women (23 with schizophrenia) completed cognitive assessments and provided blood for sex steroid assays and oxytocin at early follicular (days 2-4) and midluteal (days 20-22) phases. Men were included to verify the expected pattern of sex differences on cognitive tests.

RESULTS

Expected sex differences were observed on "female-dominant" and "male-dominant" tasks (p<0.001), but the magnitude of those differences did not differ between patients and controls (p=0.44). Cognitive performance did not change across the menstrual cycle on "female-dominant" or "male-dominant" tasks in either group. Estradiol and progesterone levels were unrelated to cognitive performance. Oxytocin levels did not change across the menstrual cycle but were positively related to performance on "female-dominant" tasks in female patients only (p<0.05).

CONCLUSIONS

Sex differences in cognitive function are preserved in schizophrenia. Oxytocin levels do not change across the cycle, but relate to enhanced performance on female dominant tests in women. Physiological levels of oxytocin may thus have a more powerful benefit in some cognitive domains than estrogens in schizophrenia.

Sex-dependent effects on tasks assessing reinforcement learning and interference inhibition

Increasing evidence suggests that the prefrontal cortex (PFC) is influenced by sex steroids and that some cognitive functions dependent on the PFC may be sexually differentiated in humans. Past work has identified a male advantage on certain complex reinforcement learning tasks, but it is unclear which latent task components are important to elicit the sex difference. The objective of the current study was to investigate whether there are sex differences on measures of response inhibition and valenced feedback processing, elements that are shared by previously studied reinforcement learning tasks. Healthy young adults (90 males, 86 females) matched in general intelligence completed the Probabilistic Selection Task (PST), a Simon task, and the Stop-Signal task. On the PST, females were more accurate than males in learning from positive (but not negative) feedback. On the Simon task, males were faster than females, especially in the face of incongruent stimuli. No sex difference was observed in Stop-Signal reaction time. The current findings provide preliminary support for a sex difference in the processing of valenced feedback and in interference inhibition.

Sex-specific strategy use and global-local processing: a perspective toward integrating sex differences in cognition

This article reviews the literature on sex-specific strategy use in cognitive tasks with the aim to carve out a link between sex differences in different cognitive tasks. I conclude that male strategies are commonly holistic and oriented toward global stimulus aspects, while female strategies are commonly decomposed and oriented toward local stimulus aspects. Thus, the strategies observed in different tasks, may depend on sex differences in attentional focus and hence sex differences in global-local processing. I hypothesize that strategy use may be sex hormone dependent and hence subject to change over the menstrual cycle as evidenced by findings in global-local processing and emotional memory. Furthermore, I propose sex hormonal modulation of hemispheric asymmetries as one possible neural substrate for this theory, thereby building on older theories, emphasizing the importance of sex differences in brain lateralization. The ideas described in the current article represent a perspective toward a unifying approach to the study of sex differences in cognition and their neural correlates.