Opinion: Focus on preclinical sex differences will not address women's and men's health disparities

Coming of age in war: Early life adversity, age at menarche, and mental health

Armed conflict and forced migration (ACFM) represent a set of extreme environments that are increasingly common for children and adolescents to experience. Adolescence may constitute a sensitive period (puberty and psychoneurological maturation) through which ACFM adversity leaves a lasting mark. Adolescence has become a focal point for analysis and intervention as it relates to the effects of early life adversity on puberty, linear growth, and mental health. Research in public health and psychological science suggests early life adversity (ELA) may accelerate puberty, heightening risks for mental health disorders. However, it is not well substantiated whether ACFM-derived adversities accelerate or delay relative pubertal timing. Secondly, ACFM provides salient context through which to probe the relationships between nutritional, psychosocial, and demographic changes and their respective impact on puberty and mental health. We conducted a narrative review which 1) examined constructions of early life adversity and their proposed influence on puberty 2) reviewed empirical findings (n = 29 studies, n = 36 samples) concerning effects of ACFM ELA on age at menarche and 3) discussed proposed relationships between early life adversity, puberty, and mental ill-health. Contrary to prior research, we found war-derived early life adversity was more consistently associated with pubertal delay than acceleration and may exert counterintuitive effects on mental health. We show that ELA cannot be operationalized in the same way across contexts and populations, especially in the presence of extreme forms of human stress and resilience. We further discuss the ethics of puberty research among conflict-affected youth.

Researchers' sex/gender identity influences how sex/gender question is investigated in neuroscience: an example from an OHBM meeting

Gender inequality and diversity in STEM is a challenging field of research. Although the relation between the sex/gender of the researcher and the scientific research practices has been previously examined, less interest has been demonstrated towards the relation between sex/gender of the researcher and the way sex/gender as a variable is explored. Here, we examine, from a neurofeminist perspective, both questions: whether sex/gender identity is related to the examination of sex/gender as a variable and whether different approaches towards examining sex/gender are being used in different topics of study within neuroscience. Using the database of submitted posters to the Organization of Human Brain Mapping 2022 annual conference, we identified abstracts examining a sex/gender-related research question. Among these target abstracts, we identified four analytical categories, varying in their degree of content-related complexity: (1) sex/gender as a covariate, (2) sex/gender as a binary variable for the study of sex/gender differences, (3) sex/gender with additional biological information, and (4) sex/gender with additional social information. Statistical comparisons between sex/gender of researcher and the target abstract showed that the proportion of abstracts from Non-binary or Other first authors compared to both Women and Men was lower for all submitted abstracts than for the target abstracts; that more researchers with sex/gender-identity other than man implemented analytical category of sex/gender with additional social information; and, for instance, that research involving cognitive, affective, and behavioural neuroscience more frequently fit into the sex/gender with additional social information-category. Word cloud analysis confirmed the validity of the four exploratorily identified analytical categories. We conclude by discussing how raising awareness about contemporary neurofeminist approaches, including perspectives from the global south, is critical to neuroscientific and societal progress.

From means to meaning in the study of sex/gender differences and similarities

The incorporation of sex and gender (S/G) related factors is commonly acknowledged as a necessary step to advance towards more personalized diagnoses and treatments for somatic, psychiatric, and neurological diseases. Until now, most attempts to integrate S/G-related factors have been reduced to identifying average differences between females and males in behavioral/ biological variables. The present commentary questions this traditional approach by highlighting three main sets of limitations: 1) Issues stemming from the use of classic parametric methods to compare means; 2) challenges related to the ability of means to accurately represent the data within groups and differences between groups; 3) mean comparisons impose a results' binarization and a binary theoretical framework that precludes advancing towards precision medicine. Alternative methods free of these limitations are also discussed. We hope these arguments will contribute to reflecting on how research on S/G factors is conducted and could be improved.

Sex-based impact of pancreatic islet stressors in GluCreERT2/Rosa26-eYFP mice

The present study examines differences in metabolic and pancreatic islet adaptative responses following streptozotocin (STZ) and hydrocortisone (HC) administration in male and female transgenic GluCreERT2/Rosa26-eYFP mice. Mice received five daily doses of STZ (50 mg/kg, i.p.) or 10 daily doses of HC (70 mg/kg, i.p.), with parameters assessed on day 11. STZ-induced hyperglycaemia was evident in both sexes, alongside impaired glucose tolerance and reduced insulin concentrations. HC also had similar metabolic effects in male and female mice resulting in classical increases of circulating insulin indicative of insulin resistance. Control male mice had larger pancreatic islets than females and displayed a greater reduction of islet and beta-cell area in response to STZ insult. In addition, female STZ mice had lower levels of beta-cell apoptosis than male counterparts. Following HC administration, female mouse islets contained a greater proportion of alpha cells when compared to males. All HC mice presented with relatively comparable increases in beta- and alpha-cell turnover rates, with female mice being slightly more susceptible to HC-induced beta-cell apoptosis. Interestingly, healthy control female mice had inherently increased alpha-to-beta-cell transdifferentiation rates, which was decreased by HC treatment. The number of glucagon-positive alpha cells altering their lineage to insulin-positive beta cells was increased in male, but not female, STZ mice. Taken together, although there was no obvious sex-specific alteration of metabolic profile in STZ or HC mice, subtle differences in pancreatic islet morphology emphasises the impact of sex hormones on islets and importance of taking care when interpreting observations between males and females.

Making a 'sex-difference fact': Ambien dosing at the interface of policy, regulation, women's health, and biology

The U.S. Food and Drug Administration's (FDA) 2013 decision to lower recommended Ambien dosing for women has been widely cited as a hallmark example of the importance of sex differences in biomedicine. Using regulatory documents, scientific publications, and media coverage, this article analyzes the making of this highly influential and mobile 'sex-difference fact'. As we show, the FDA's decision was a contingent outcome of the drug approval process. Attending to how a contested sex-difference fact came to anchor elite women's health advocacy, this article excavates the role of regulatory processes, advocacy groups, and the media in producing perceptions of scientific agreement while foreclosing ongoing debate, ultimately enabling the stabilization of a binary, biological sex-difference fact and the distancing of this fact from its conditions of construction.

Sex and gender in infection and immunity: addressing the bottlenecks from basic science to public health and clinical applications

Although sex and gender are recognized as major determinants of health and immunity, their role is rarely considered in clinical practice and public health. We identified six bottlenecks preventing the inclusion of sex and gender considerations from basic science to clinical practice, precision medicine and public health policies. (i) A terminology-related bottleneck, linked to the definitions of sex and gender themselves, and the lack of consensus on how to evaluate gender. (ii) A data-related bottleneck, due to gaps in sex-disaggregated data, data on trans/non-binary people and gender identity. (iii) A translational bottleneck, limited by animal models and the underrepresentation of gender minorities in biomedical studies. (iv) A statistical bottleneck, with inappropriate statistical analyses and results interpretation. (v) An ethical bottleneck posed by the underrepresentation of pregnant people and gender minorities in clinical studies. (vi) A structural bottleneck, as systemic bias and discriminations affect not only academic research but also decision makers. We specify guidelines for researchers, scientific journals, funding agencies and academic institutions to address these bottlenecks. Following such guidelines will support the development of more efficient and equitable care strategies for all.

Sex similarities and dopaminergic differences in interval timing

Rodent behavioral studies have largely focused on male animals, which has limited the generalizability and conclusions of neuroscience research. Working with humans and rodents, we studied sex effects during interval timing that requires participants to estimate an interval of several seconds by making motor responses. Interval timing requires attention to the passage of time and working memory for temporal rules. We found no differences between human females and males in interval timing response times (timing accuracy) or the coefficient of variance of response times (timing precision). Consistent with prior work, we also found no differences between female and male rodents in timing accuracy or precision. In female rodents, there was no difference in interval timing between estrus and diestrus cycle stages. Because dopamine powerfully affects interval timing, we also examined sex differences with drugs targeting dopaminergic receptors. In both female and male rodents, interval timing was delayed after administration of sulpiride (D2-receptor antagonist), quinpirole (D2-receptor agonist), and SCH-23390 (D1-receptor antagonist). By contrast, after administration of SKF-81297 (D1-receptor agonist), interval timing shifted earlier only in male rodents. These data illuminate sex similarities and differences in interval timing. Our results have relevance for rodent models of both cognitive function and brain disease by increasing represenation in behavioral neuroscience.

Sex and estrous cycle affect experience-dependent plasticity in mouse primary visual cortex

Sex hormones can affect cellular physiology and modulate synaptic plasticity, but it is not always clear whether or how sex-dependent differences identified in vitro express themselves as functional dimorphisms in the brain. Historically, most experimental neuroscience has been conducted using only male animals and the literature is largely mute about whether including female mice in will introduce variability due to inherent sex differences or endogenous estrous cycles. Though this is beginning to change following an NIH directive that sex should be included as a factor in vertebrate research, the lack of information raises practical issues around how to design experimental controls and apply existing knowledge to more heterogeneous populations. Various lines of research suggest that visual processing can be affected by sex and estrous cycle stage. For these reasons, we performed a series of in vivo electrophysiological experiments to characterize baseline visual function and experience-dependent plasticity in the primary visual cortex (V1) of male and female mice. We find that sex and estrous stage have no statistically significant effect on baseline acuity measurements, but that both sex and estrous stage have can modulate two mechanistically distinct forms of experience dependent cortical plasticity. We also demonstrate that resulting variability can be largely controlled with appropriate normalizations. These findings suggest that V1 plasticity can be used for mechanistic studies focusing on how sex hormones effect experience dependent plasticity in the mammalian cortex.

Sex Differences in Pharmacokinetics

Because women have been excluded from most clinical trials, assessment of sex differences in pharmacokinetics is available for a minority of currently prescribed drugs. In a 2020 analysis, substantial pharmacokinetic (PK) sex differences were established for 86 drugs: women given the same drug dose as men routinely generated higher blood concentrations and longer drug elimination times than men. 96% of drugs with higher PK values in women were associated with a higher incidence of adverse drug reactions (ADRs) in women than men; in the small number of instances when PKs of men exceeded those of women, this sex difference positively predicted male-biased ADRs in only 29% of cases. The absence of sex-stratified PK information for many medications raises the concern that sex differences in pharmacokinetics may be widespread and of clinical significance, contributing to sex-specific patterns of ADRs. Administering equal drug doses to women and men neglects sex differences in pharmacokinetics and body weight, risks overmedication of women, and contributes to female-biased ADRs. Evidence-based dosing adjustments are recommended to counteract this sex bias.

Sex differences in allometry for phenotypic traits in mice indicate that females are not scaled males

Sex differences in the lifetime risk and expression of disease are well-known. Preclinical research targeted at improving treatment, increasing health span, and reducing the financial burden of health care, has mostly been conducted on male animals and cells. The extent to which sex differences in phenotypic traits are explained by sex differences in body weight remains unclear. We quantify sex differences in the allometric relationship between trait value and body weight for 363 phenotypic traits in male and female mice, recorded in >2 million measurements from the International Mouse Phenotyping Consortium. We find sex differences in allometric parameters (slope, intercept, residual SD) are common (73% traits). Body weight differences do not explain all sex differences in trait values but scaling by weight may be useful for some traits. Our results show sex differences in phenotypic traits are trait-specific, promoting case-specific approaches to drug dosage scaled by body weight in mice.

Design a protocol to investigate the effects of climate change in vivo

Climate change has a variety of effects on communities and the environment, most of which have been directly addressed, such as floods, droughts, and fires. To date, the impacts of climate change on health in in vivo conditions have not been assessed, and no protocol has been developed in this regard. Therefore, the purpose of the current study is to develop a protocol as well as design and build a pilot to deal with climate change in vivo to show the direct effects of climate change on health. For this purpose, twenty specialists, comprising ten experts active in field climate and 10 experts in field medicine and anatomy, have been consulted to design the proposed exposure protocol using the Delphi method. According to the prepared protocol, an exposure pilot was then designed and built, which provides the climatic conditions for animal exposure with a fully automatic HMI-PLC system. The results showed the average 12:12-h day/night temperature, humidity, and circadian cycle for three consecutive ten-year periods selected for exposure of 1-month-old male rats. The duration of the exposure period is four months, which is equivalent to a ten-year climatic period. This study is a framework and a starting point for examining the effects of climate change on in vivo conditions that have not yet been considered.

Fairly Criticized, or Politicized? Conflicts in the Neuroscience of Sex Differences in the Human Brain

Investigations of sex differences in the human brain take place on politically sensitive terrain. While some scholars express concern that gendered biases and stereotypes remain embedded in scientific research, others are alarmed about the politicization of science. To help better understand these debates, this review sets out three kinds of conflicts that can arise in the neuroscience of sex differences: academic freedom versus gender equality; frameworks, background assumptions, and dominant methodologies; and inductive risk and social values. The boundaries between fair criticism and politicization are explored for each kind of conflict, pointing to ways in which the academic community can facilitate fair criticism while protecting against politicization.

Contextualising sex and gender research to improve women's health: An early- and mid-career researcher perspective

The field of sex and gender research in health and medicine is growing, and many early- and mid-career researchers (EMCRs) are developing skills in this area. As EMCRs specialising in sex and gender research, we aim to better understand sex- and gender-based determinants of human health, challenge long-standing and pervasive gender biases, and contribute to improving the evidence base upon which clinical guidelines and policy interventions are developed. To effectively achieve these goals, we believe that EMCRs would benefit from understanding the challenges of working in this space and participate in driving change in three key areas. First, in creating greater links between the goals of sex and gender research and addressing systemic bias against women and gender minorities, to effectively translate knowledge about sex and gender differences into improved health outcomes. Second, in expanding the reach of sex and gender research to address women's health in an intersectional way and ensure that it also benefits the health of men, transgender and gender-diverse people and those who are intersex. Third, in working with others in the scientific community to improve methods for sex and gender research, including updating data collection practises, ensuring appropriate statistical analyses and shifting scientific culture to recognise the importance of null findings. By improving focus on these three areas, we see greater potential to translate this research to improve women's health and reduce health inequities for all.

Beneficial effects of whole-body vibration exercise for brain disorders in experimental studies with animal models: a systematic review

Brain disorders have been a health challenge and is increasing over the years. Early diagnosis and interventions are considered essential strategies to treat patients at risk of brain disease. Physical exercise has shown to be beneficial for patients with brain diseases. A type of exercise intervention known as whole-body vibration (WBV) exercise gained increasing interest. During WBV, mechanical vibrations, produced by a vibrating platform are transmitted, to the body. The purpose of the current review was to summarize the effects of WBV exercise on brain function and behavior in experimental studies with animal models. Searches were performed in EMBASE, PubMed, Scopus and Web of Science including publications from 1960 to July 2021, using the keywords "whole body vibration" AND (animal or mice or mouse or rat or rodent). From 1284 hits, 20 papers were selected. Rats were the main animal model used (75%) followed by mice (20%) and porcine model (5%), 16 studies used males species and 4 females. The risk of bias, accessed with the SYRCLE Risk of Bias tool, indicated that none of the studies fulfilled all methodological criteria, resulting in possible bias. Despite heterogeneity, the results suggest beneficial effects of WBV exercise on brain functioning, mainly related to motor performance, coordination, behavioral control, neuronal plasticity and synapse function. In conclusion, the findings observed in animal studies justifies continued clinical research regarding the effectiveness and potential of WBV for the treatment of various types of brain disorders such as trauma, developmental disorders, neurogenetic diseases and other neurological diseases.

Why "sex as a biological variable" conflicts with precision medicine initiatives

Policies that require male-female sex comparisons in all areas of biomedical research conflict with the goal of improving health outcomes through context-sensitive individualization of medical care. Sex, like race, requires a rigorous, contextual approach in precision medicine. A "sex contextualist" approach to gender-inclusive medicine better aligns with this aim.

Sins of inquiry: How to criticize scientific pursuits

Criticism is a staple of the scientific enterprise and of the social epistemology of science. Philosophical discussions of criticism have traditionally focused on its roles in relation to objectivity, confirmation, and theory choice. However, attention to criticism and to criticizability should also inform our thinking about scientific pursuits: the allocation of resources with the aim of developing scientific tools and ideas. In this paper, we offer an account of scientific pursuitworthiness which takes criticizability as its starting point. We call this the apokritic model of pursuit. Its core ideas are that pursuits are practices governed by norms for asking and answering questions, and that criticism arises from the breach of these norms. We illustrate and advertise our approach using examples from institutional grant review, neuroscience, and sociology. We show that the apokritic model can unify several indices of criticizability, that it can account for the importance of criticizing pursuits in scientific practice, and that it can offer ameliorative advice to erstwhile pursuers.

Lost in translation? Beyond sex as a biological variable in animal research

In this article, I develop a feminist posthumanist account of biomedical policymaking as a material-discursive intervention that shapes the emergence of phenomena in the scientific laboratory. The setting is United States (U.S.) biomedicine, where a recent policy of the National Institutes of Health has mandated the consideration of sex in basic and preclinical research. Called Sex as a Biological Variable (SABV), the mandate configures cell lines and animal models as the next frontier in the project of advancing gender equity in biomedical research. Given sex and gender are increasingly recognised as having complex, entangled, and dynamic effects on human health and illness, how do laboratory animals respond to their attempted enrolment in this regulatory intervention? Through a qualitative analysis of this policy domain, I show how laboratory animals reveal the context-specific character of sex, its multiplicity and elusiveness as a so-called biological variable, and the considerable work needed to shore up human ideologies of sex as a pervasive cross-species form of binary difference. I suggest that while regulatory interventions constrain patterns of mattering, they also serve as agential openings in which laboratory animals can 'kick back' and reconfigure the pursuit of knowledge, particularly as it relates to difference and health.

Sex bias in alcohol research: A 20-year comparative study

We aimed to assess the sex-inclusive and sex-based analysis bias in alcohol research for the past 20 years. Data were abstracted from 2988 original research articles published from 2000 through 2019 in 51 representative journals across 9 biomedical disciplines. An analysis in 5-year intervals revealed that the percentage of studies using participants of both sexes was significantly higher between 2015 and 2019 than between 2000 and 2014. When stratified, clinical studies showed a higher percentage of both-sex studies compared to basic studies using animals. The reasons for the use of single-sex cohorts mainly included insufficient participant numbers and misconceptions surrounding the hormonal variability of females. Implementation of the NIH SABV policy promoted the ratio of NIH-funded papers with sex-based analyses. In conclusion, sex bias in alcohol-related biomedical studies has improved over the past 20 years, particularly after the implementation of the SABV policy. Although clinical studies increasingly included sex-based analysis, basic studies were biased towards the use of males.

What is normal bone health? A bioarchaeological perspective on meaningful measures and interpretations of bone strength, loss, and aging

Bioarchaeological (the study of archeological human remains together with contextual and documentary evidence) offers a unique vantage point to examine variation in skeletal morphology related to influences such as activity, disease, and nutrition. The human skeleton is composed of a dynamic tissue that is forged by biocultural factors over the entire life course, providing a record of individual, and community history. Various aspects of adult bone health, particularly bone maintenance and loss and the associated skeletal disease osteoporosis, have been examined in numerous past populations. The anthropological study of bone loss has traditionally focused on the signature of postmenopausal aging, costs of reproduction, and fragility in females. The a priori expectation of normative sex-related bone loss/fragility in bioanthropological studies illustrates the wider gender-ideological bias that continues in research design and data analysis in the field. Contextualized data on bone maintenance and aging in the archeological record show that patterns of bone loss do not constitute predictable consequences of aging or biological sex. Instead, the critical examination of bioarchaeological data highlights the complex and changing processes that craft the human body over the life course, and calls for us to question the ideal or "normal" range of bone quantity and quality in the human skeleton, and to critically reflect on what measures are actually biologically and/or socially meaningful.

Challenging the binary: Gender/sex and the bio-logics of normalcy

BACKGROUND

We are witnessing renewed debates regarding definitions and boundaries of human gender/sex, where lines of genetics, gonadal hormones, and secondary sex characteristics are drawn to defend strict binary categorizations, with attendant implications for the acceptability and limits of gender identity and diversity.

AIMS

Many argue for the need to recognize the entanglement of gender/sex in humans and the myriad ways that gender experience becomes biology; translating this theory into practice in human biology research is essential. Biological anthropology is well poised to contribute to these societal conversations and debates. To do this effectively, a reconsideration of our own conceptions of gender/sex, gender identity, and sexuality is necessary.

METHODS

In this article, we discuss biological variation associated with gender/sex and propose ways forward to ensure we are engaging with gender/sex diversity. We base our analysis in the concept of "biological normalcy," which allows consideration of the relationships between statistical distributions and normative views. We address the problematic reliance on binary categories, the utilization of group means to represent typical biologies, and document ways in which binary norms reinforce stigma and inequality regarding gender/sex, gender identity, and sexuality.

DISCUSSION AND CONCLUSIONS

We conclude with guidelines and methodological suggestions for how to engage gender/sex and gender identity in research. Our goal is to contribute a framework that all human biologists can use, not just those who work with gender or sexually diverse populations. We hope that in bringing this perspective to bear in human biology, that novel ideas and applications will emerge from within our own discipline.

Co-production, multiplied: Enactments of sex as a biological variable in US biomedicine

In 2016 the US National Institutes of Health introduced a policy mandating consideration of Sex as a Biological Variable (SABV) in preclinical research. In this article, I ask what, precisely, is meant by the designation of sex as a 'biological variable', and how has its inclusion come to take the form of a policy mandate? Given the well documented complexity of 'sex' and the degree to which it is politically and scientifically contested, its enactment via policy as a biological variable is not a given. I explore how sex is multiply enacted in efforts to legitimate and realize the SABV policy and consider how the analytical lens of co-production sheds light on how and why this occurs. I show that the policy works to reassert scientific and political order by addressing two institutional concerns: the so-called reproducibility crisis in preclinical research, and pervasive gender inequality across the institution of biomedicine. From here, the entity that underpins this effort - sex as a biological variable - becomes more than one thing, with enactments ranging from an assigned category, to an outcome, to a causal biological force in its own right. Sex emerges as simultaneously entangled with yet distinct from gender, and binary (female/male) yet complex in its variation. I suggest that it is in the very attempt to delineate natural from social order, and in the process create the conditions to privilege a particular kind of science and account of embodied difference, that ontological multiplicity becomes readily visible. That this multiplicity goes unrecognized points to the unifying role of an overarching ideological commitment to sex as a presumed binary and biological scientific object, the institutional dominance of which is never guaranteed.

Paradigms of Sex Research and Women in STEM

Scientists' identities and social locations influence their work, but the content of scientific work can also influence scientists. Theory from feminist science studies, autoethnographic accounts, interviews, and experiments indicate that the substance of scientific research can have profound effects on how scientists are treated by colleagues and their sense of belonging in science. I bring together this disparate literature under the framework of professional cultures and show population-level trends supporting it. Drawing on the Survey of Earned Doctorates and the Web of Science, I use computational social science tools to argue that the way scientists write about sex in their research influences the future gender ratio of PhDs awarded across 53 subfields of the life sciences over a span of 47 years. Specifically, I show that a critical paradigm of "feminist biology" that seeks to de-essentialize sex and gender corresponds to increases in women's graduation rates, while "sex difference" research-sometimes called "neurosexism" because of its emphasis on essential, categorical differences-has negative effects on women's graduation rates in most fields.

"You Can't Ignore a Number This Big": Gender, Risk, and Responsibility in Online Advocacy for Women's Brain Health

Alzheimer's disease affects more women than men and has therefore been highlighted as a women's issue. However, there is much debate regarding the nature of this gap, with some studies pointing to sex/gender differences in longevity to explain the disparity. Against this background of empirical uncertainty, we ask how online women's brain health campaigns position women as specifically at risk of developing the disease. Using a multimodal approach, we examine how these platforms relate womanhood to risk, prevention, and responsibility. Four main themes emerged: risk quantification, risk management, risk dispersion, and the gendering of risk. We confirm previous studies that identified a dual discourse in which Alzheimer's is represented as both a catastrophic threat and as a fate that individuals can and must prevent. We find that both constructions are intensified on women-oriented platforms compared with nonspecific websites. Ethical implications of the individualization and gendering of risk and responsibility are discussed.

Evidence-Based Medicine and the Potential for Inclusion of Non-Biomedical Health Systems: The Case for Taijiquan

Many traditional and complementary and alternative healthcare systems or practices, such as Traditional Chinese Medicine, taijiquan, or acupuncture, are easily found in many North American and European cities. For the most part these practices are not accredited, and their validation remains limited. This is primarily the result of the lack of modern scientific research. Additionally, the studies that are performed rely on evidence and research designs that often negate the true features of these practices with a loss of authenticity. Is it possible or even desirable for these systems to acquire accreditation and inclusion? If so, given the apparent, subjective nature of these practices, can a pluralistic approach to healthcare that retains the Western values of science and medicine be developed that yet respects the diversity of different concepts about life, health and services while permitting these practices to maintain their authenticity? And is it possible to develop a regulatory framework that practitioners can use? The current paper examines questions concerning the uses of non-Western healthcare practices without the loss of their authentic nature. The process of integration is here examined using the inclusion of taijiquan as a health-promoting martial art as the model.

COVID-19 and the gendered markets of people and products: explaining inequalities in infections and deaths

COVID-19 has exposed and exploited existing inequalities in gender to drive inequities in health outcomes. Evidence illustrates the relationship between occupation, ethnicity and gender to increase risk of infection in some places. Higher death rates are seen among people also suffering from non-communicable diseases - e.g. heart disease and lung disease driven by exposure to harmful patterns of exposure to corporate products (tobacco, alcohol, ultra-processed foods), corporate by-products (e.g. outdoor air pollution) or gendered corporate processes (e.g. gendered occupational risk). The paper argues that institutional gender blindness in the health system means that underlying gender inequalities have not been taken into consideration in policies and programmatic responses to COVID-19.

Mechanistic Models of Signaling Pathways Reveal the Drug Action Mechanisms behind Gender-Specific Gene Expression for Cancer Treatments

Despite the existence of differences in gene expression across numerous genes between males and females having been known for a long time, these have been mostly ignored in many studies, including drug development and its therapeutic use. In fact, the consequences of such differences over the disease mechanisms or the drug action mechanisms are completely unknown. Here we applied mechanistic mathematical models of signaling activity to reveal the ultimate functional consequences that gender-specific gene expression activities have over cell functionality and fate. Moreover, we also used the mechanistic modeling framework to simulate the drug interventions and unravel how drug action mechanisms are affected by gender-specific differential gene expression. Interestingly, some cancers have many biological processes significantly affected by these gender-specific differences (e.g., bladder or head and neck carcinomas), while others (e.g., glioblastoma or rectum cancer) are almost insensitive to them. We found that many of these gender-specific differences affect cancer-specific pathways or in physiological signaling pathways, also involved in cancer origin and development. Finally, mechanistic models have the potential to be used for finding alternative therapeutic interventions on the pathways targeted by the drug, which lead to similar results compensating the downstream consequences of gender-specific differences in gene expression.

Sex differences in pharmacokinetics predict adverse drug reactions in women

BACKGROUND

Women experience adverse drug reactions, ADRs, nearly twice as often as men, yet the role of sex as a biological factor in the generation of ADRs is poorly understood. Most drugs currently in use were approved based on clinical trials conducted on men, so women may be overmedicated. We determined whether sex differences in drug pharmacokinetics, PKs, predict sex differences in ADRs.

METHODS

Searches of the ISI Web of Science and PubMed databases were conducted with combinations of the terms: drugs, sex or gender, pharmacokinetics, pharmacodynamics, drug safety, drug dose, and adverse drug reaction, which yielded over 5000 articles with considerable overlap. We obtained information from each relevant article on significant sex differences in PK measures, predominantly area under the curve, peak/maximum concentrations, and clearance/elimination rates. ADRs were identified from every relevant article and recorded categorically as female-biased, male-biased, or not sex-biased.

RESULTS

For most of the FDA-approved drugs examined, elevated blood concentrations and longer elimination times were manifested by women, and these PKs were strongly linked to sex differences in ADRs. Of the 86 drugs evaluated, 76 had higher PK values in women; for 59 drugs with clinically identifiable ADRs, sex-biased PKs predicted the direction of sex-biased ADRs in 88% of cases. Ninety-six percent of drugs with female-biased PK values were associated with a higher incidence of ADRs in women than men, but only 29% of male-biased PKs predicted male-biased ADRs. Accessible PK information is available for only a small fraction of all drugs CONCLUSIONS: Sex differences in pharmacokinetics strongly predict sex-specific ADRs for women but not men. This sex difference was not explained by sex differences in body weight. The absence of sex-stratified PK information in public records for hundreds of drugs raises the concern that sex differences in PK values are widespread and of clinical significance. The common practice of prescribing equal drug doses to women and men neglects sex differences in pharmacokinetics and dimorphisms in body weight, risks overmedication of women, and contributes to female-biased adverse drug reactions. We recommend evidence-based dose reductions for women to counteract this sex bias.

Qualitative sex differences in pain processing: emerging evidence of a biased literature

Although most patients with chronic pain are women, the preclinical literature regarding pain processing and the pathophysiology of chronic pain has historically been derived overwhelmingly from the study of male rodents. This Review describes how the recent adoption by a number of funding agencies of policies mandating the incorporation of sex as a biological variable into preclinical research has correlated with an increase in the number of studies investigating sex differences in pain and analgesia. Trends in the field are analysed, with a focus on newly published findings of qualitative sex differences: that is, those findings that are suggestive of differential processing mechanisms in each sex. It is becoming increasingly clear that robust differences exist in the genetic, molecular, cellular and systems-level mechanisms of acute and chronic pain processing in male and female rodents and humans.

Sex bias and omission in neuroscience research is influenced by research model and journal, but not reported NIH funding

Neuroscience research has historically demonstrated sex bias that favors male over female research subjects, as well as sex omission, which is the lack of reporting sex. Here we analyzed the status of sex bias and omission in neuroscience research published across six different journals in 2017. Regarding sex omission, 16% of articles did not report sex. Regarding sex bias, 52% of neuroscience articles reported using both males and females, albeit only 15% of articles using both males and females reported assessing sex as an experimental variable. Overrepresentation of the sole use of males compared to females persisted (26% versus 5%, respectively). Sex bias and omission differed across research models, but not by reported NIH funding status. Sex omission differed across journals. These findings represent the latest information regarding the complex status of sex in neuroscience research and illustrate the continued need for thoughtful and informed action to enhance scientific discovery.

Biological intersection of sex, age, and environment in the corticotropin releasing factor (CRF) system and alcohol

The neuropeptide corticotropin-releasing factor (CRF) is critical in neural circuit function and behavior, particularly in the context of stress, anxiety, and addiction. Despite a wealth of preclinical evidence for the efficacy of CRF receptor 1 antagonists in reducing behavioral pathology associated with alcohol exposure, several clinical trials have had disappointing outcomes, possibly due to an underappreciation of the role of biological variables. Although he National Institutes of Health (NIH) now mandate the inclusion of sex as a biological variable in all clinical and preclinical research, the current state of knowledge in this area is based almost entirely on evidence from male subjects. Additionally, the influence of biological variables other than sex has received even less attention in the context of neuropeptide signaling. Age (particularly adolescent development) and housing conditions have been shown to affect CRF signaling and voluntary alcohol intake, and the interaction between these biological variables is particularly relevant to the role of the CRF system in the vulnerability or resilience to the development of alcohol use disorder (AUD). Going forward, it will be important to include careful consideration of biological variables in experimental design, reporting, and interpretation. As new research uncovers conditions in which sex, age, and environment play major roles in physiological and/or pathological processes, our understanding of the complex interaction between relevant biological variables and critical signaling pathways like the CRF system in the cellular and behavioral consequences of alcohol exposure will continue to expand ultimately improving the ability of preclinical research to translate to the clinic. This article is part of the special issue on Neuropeptides.

Sex/gender differences in neurology and psychiatry: Autism

Autism is a heterogenous set of early-onset neurodevelopmental conditions that are more prevalent in males than in females. Due to the high phenotypic, neurobiological, developmental, and etiological heterogeneity in the autism spectrum, recent research programs are increasingly exploring whether sex- and gender-related factors could be helpful markers to clarify the heterogeneity in autism and work toward a personalized approach to intervention and support. In this chapter, we summarize recent clinical and neuroscientific research addressing sex/gender influences in autism and explore how sex/gender-based investigations shed light on similar or different underlying neurodevelopmental mechanisms of autism by sex/gender. We review evidence that may help to explain some of the underlying sex-related biological mechanisms associated with autism, including genetics and the effects of sex steroid hormones in the prenatal environment. We conclude that current research points toward coexisting quantitative and, perhaps more evidently, qualitative sex/gender-modulation effects in autism across multiple neurobiological aspects. However, converging findings of specific neurobiological presentations and sex/gender-informed mechanisms cutting across the many subgroups within the autism spectrum are still lacking. Future research should use big data approaches and new stratification methods to decompose sex/gender-related heterogeneity in autism and work toward personalized, sex/gender-informed intervention and support for autistic people.

Sex bias in basic and preclinical noise-induced hearing loss research

Introduction:

Sex differences in brain biochemistry, physiology, structure, and function have been gaining increasing attention in the scientific community. Males and females can have different responses to medications, diseases, and environmental variables. A small number of the approximately 7500 studies of noise-induced hearing loss (NIHL) have identified sex differences, but the mechanisms and characterization of these differences have not been thoroughly studied. The National Institutes of Health (NIH) issued a mandate in 2015 to include sex as a biological variable in all NIH-funded research beginning in January 2016.

Materials and Methods:

In the present study, the representation of sex as a biological variable in preclinical and basic studies of NIHL was quantified for a 5-year period from January 2011 to December 2015 prior to the implementation of the NIH mandate.

Results:

The analysis of 210 basic and preclinical studies showed that when sex is specified, experiments are predominantly performed on male animals.

Discussion:

This bias is present in studies completed in the United States and foreign institutions, and the proportion of studies using only male participants has actually increased over the 5-year period examined.

Conclusion:

These results underscore the need to invest resources in studying NIHL in both sexes to better understand how sex shapes the outcomes and to optimize treatment and prevention strategies.

Addressing the dearth of critical gender analysis in public health and medical pedagogy: an interdisciplinary seminar to generate student-created teaching examples

Gender-based analysis in public health is a systematic examination of how population health is shaped by systems of gender relations, involving policies and laws, programs and services, research priorities, social norms and practices, and public discourse. To address the paucity of critical gender-based analysis training in most public health, medical, and health policy courses, we designed the capstone course in the Women, Gender, and Health (WGH) Interdisciplinary Concentration at the Harvard T.H. Chan School of Public Health. This course enables students to develop brief teaching examples to expose students in non-WGH courses to gender-based analysis (e.g., challenging simplistic conflations of gender and sex). The assignment has yielded 19 teaching examples (several available online at no cost) and offers a model that can be used to address analogous curriculum gaps in relation to other social determinants of health, including racism, social class, sexuality, and immigration.

Sex and gender bias in the experimental neurosciences: the case of the maternal immune activation model

Recent and rapidly developing movements relating to the increasing awareness and reports of gender bias, discrimination, and abuse have reached the academic environments. The consideration that negative attitudes toward women and abuse of power creates a hostile environment for female scientists, facilitating sexual harassment and driving women out of science, can be easily related to. Rationally inaccessible gender biases are not only evident at the level of the researchers, but are also paralleled by a corresponding imbalance at the level of the research subjects. Here, we focus on the maternal immune activation (MIA) animal model to illustrate exemplarily the current state of ex-/inclusion of female research subjects and the consideration of sex as biological variable in the basic neurosciences. We demonstrate a strong sex disparity with a major emphasis on male animals in studies examining behavioral and neurochemical alterations in MIA offspring. We put forward the hypothesis that this neglect of female subjects in basic research may stem from a hard-wired sex/gender bias, which may also be reflected in a similar attitude toward female scientists. We suggest exploring the possibility that by dismantling sex bias and male dominance in basic research one would get an additional handle on favorably modifying the perception and appreciation for women in science.

Inclusion of females does not increase variability in rodent research studies

The underrepresentation of female subjects in animal research has gained attention in recent years, and new NIH guidelines aim to address this problem early, at the grant proposal stage. Many researchers believe that use of females will hamper research because of the need for increased sample sizes, and increased costs. Here I review empirical research across multiple rodent species and traits that demonstrates that females are not more variable than males, and that for most traits, female estrous cyclicity need not be considered. I present statistical simulations illustrating how factorial designs can reduce the need for additional research subjects, and discuss cultural issues around the inclusion of male and female subjects in research.

Reprint of: Environmental toxicology and omics: A question of sex

Molecular initiating events and downstream transcriptional/proteomic responses provide valuable information for adverse outcome pathways, which can be used predict the effects of chemicals on physiological systems. There has been a paucity of research that addresses sex-specific expression profiling in toxicology and due to cost, time, and logistic considerations, sex as a variable has not been widely considered. In response to this deficiency, federal agencies in the United States, Canada, and Europe have highlighted the importance of including sex as a variable in scientific investigations. Using case studies from both aquatic and mammalian toxicology, we report that there can be less than ~20-25% consensus in how the transcriptome and proteome of each sex responds to chemicals. Chemicals that have been shown to elicit sex-specific responses in the transcriptome or proteome include pharmaceuticals, anti-fouling agents, anticorrosive agents, and fungicides, among others. Sex-specific responses in the transcriptome and proteome are not isolated to whole animals, as investigations demonstrate that primary cell cultures isolated from each sex responds differently to toxicants. This signifies that sex is important, even in cell lines. Sex has significant implications for predictive toxicology, and both male and female data are required to improve robustness of adverse outcome pathways.

BIOLOGICAL SIGNIFICANCE

Clinical toxicology recognizes that sex is an important variable, as pharmacokinetics (ADME; absorption, distribution, metabolism, and excretion) can differ between females and males. However, few studies in toxicology have explored the implication of sex in relation to the transcriptome and proteome of whole organisms. High-throughput molecular approaches are becoming more frequently applied in toxicity screens (e.g. pre-clinical experiments, fish embryos, cell lines, synthetic tissues) and such data are expected to build upon reporter-based cell assays (e.g. receptor activation, enzyme inhibition) used in toxicant screening programs (i.e. Tox21, ToxCast, REACH). Thus, computational models can more accurately predict the diversity of adverse effects that can occur from chemical exposure within the biological system. Our studies and those synthesized from the literature suggest that the transcriptome and proteome of females and males respond quite differentially to chemicals. This has significant implications for predicting adverse effects in one sex when using molecular data generated in the other sex. While molecular initiating events are not expected to differ dramatically between females and males (i.e. an estrogen binds estrogen receptors in both sexes), it is important to acknowledge that the downstream transcriptomic and proteomic responses can differ based upon the presence/absence of co-regulators and inherent sex-specific variability in regulation of transcriptional and translational machinery. Transcriptomic and proteomic studies also reveal that cell processes affected by chemicals can differ due to sex, and this can undoubtedly lead to sex-specific physiological responses.

Sex in basic research: concepts in the cardiovascular field

Women and men, female and male animals and cells are biologically different, and acknowledgement of this fact is critical to advancing medicine. However, incorporating concepts of sex-specific analysis in basic research is largely neglected, introducing bias into translational findings, clinical concepts and drug development. Research funding agencies recently approached these issues but implementation of policy changes in the scientific community is still limited, probably due to deficits in concepts, knowledge and proper methodology. This expert review is based on the EUGenMed project (www.eugenmed.eu) developing a roadmap for implementing sex and gender in biomedical and health research. For sake of clarity and conciseness, examples are mainly taken from the cardiovascular field that may serve as a paradigm for others, since a significant amount of knowledge how sex and oestrogen determine the manifestation of many cardiovascular diseases (CVD) has been accumulated. As main concepts for implementation of sex in basic research, the study of primary cell and animals of both sexes, the study of the influence of genetic vs. hormonal factors and the analysis of sex chromosomes and sex specific statistics in genome wide association studies (GWAS) are discussed. The review also discusses methodological issues, and analyses strength, weaknesses, opportunities and threats in implementing sex-sensitive aspects into basic research.

Organ-on-a-Chip Systems for Women's Health Applications

Biomedical research, for a long time, has paid little attention to the influence of sex in many areas of study, ranging from molecular and cellular biology to animal models and clinical studies on human subjects. Many studies solely rely on male cells/tissues/animals/humans, although there are profound differences in male and female physiology, which can significantly impact disease mechanisms, toxicity of compounds, and efficacy of pharmaceuticals. In vitro systems have been traditionally very limited in their capacity to recapitulate female-specific physiology and anatomy such as dynamic sex-hormone levels and the complex interdependencies of female reproductive tract organs. However, the advent of microphysiological organ-on-a-chip systems, which attempt to recreate the 3D structure and function of human organs, now gives researchers the opportunity to integrate cells and tissues from a variety of individuals. Moreover, adding a dynamic flow environment allows mimicking endocrine signaling during the menstrual cycle and pregnancy, as well as providing a controlled microfluidic environment for pharmacokinetic modeling. This review gives an introduction into preclinical and clinical research on women's health and discusses where organ-on-a-chip systems are already utilized or have the potential to deliver new insights and enable entirely new types of studies.

Problems and Progress regarding Sex Bias and Omission in Neuroscience Research

Neuroscience research has historically ignored female animals. This neglect comes in two general forms. The first is sex bias, defined as favoring one sex over another; in this case, male over female. The second is sex omission, which is the lack of reporting sex. The recognition of this phenomenon has generated fierce debate across the sciences. Here we test whether sex bias and omission are still present in the neuroscience literature, whether studies employing both males and females neglect sex as an experimental variable, and whether sex bias and omission differs between animal models and journals. To accomplish this, we analyzed the largest-ever number of neuroscience articles for sex bias and omission: 6636 articles using mice or rats in 6 journals published from 2010 to 2014. Sex omission is declining, as increasing numbers of articles report sex. Sex bias remains present, as increasing numbers of articles report the sole use of males. Articles using both males and females are also increasing, but few report assessing sex as an experimental variable. Sex bias and omission varies substantially by animal model and journal. These findings are essential for understanding the complex status of sex bias and omission in neuroscience research and may inform effective decisions regarding policy action.

Enhancing Scientific Foundations to Ensure Reproducibility: A New Paradigm

Progress in science is dependent on a strong foundation of reliable results. The publish or perish paradigm in research, coupled with an increase in retracted articles from the peer-reviewed literature, is beginning to erode the trust of both the scientific community and the public. The NIH is combating errors by requiring investigators to follow new guidelines addressing scientific premise, experimental design, biological variables, and authentication of reagents. Herein, we discuss how implementation of NIH guidelines will help investigators proactively address pitfalls of experimental design and methods. Careful consideration of the variables contributing to reproducibility helps ensure robust results. The NIH, investigators, and journals must collaborate to ensure that quality science is funded, explored, and published.

Considering Sex as a Biological Variable Will Be Valuable for Neuroscience Research

The recently implemented National Institutes of Health policy requiring that grant applicants consider sex as a biological variable in the design of basic and preclinical animal research studies has prompted considerable discussion within the neuroscience community. Here, we present reasons to be optimistic that this new policy will be valuable for neuroscience, and we suggest some ways for neuroscientists to think about incorporating sex as a variable in their research.

Prevalence of sexual dimorphism in mammalian phenotypic traits

The role of sex in biomedical studies has often been overlooked, despite evidence of sexually dimorphic effects in some biological studies. Here, we used high-throughput phenotype data from 14,250 wildtype and 40,192 mutant mice (representing 2,186 knockout lines), analysed for up to 234 traits, and found a large proportion of mammalian traits both in wildtype and mutants are influenced by sex. This result has implications for interpreting disease phenotypes in animal models and humans.

Systemic dissection of sexually dimorphic phenotypes in mice is lacking. Here, Karp and the International Mouse Phenotype Consortium show that approximately 10% of qualitative traits and 56% of quantitative traits in mice as measured in laboratory setting are sexually dimorphic.

A Guide for the Design of Pre-clinical Studies on Sex Differences in Metabolism

In animal models, the physiological systems involved in metabolic homeostasis exhibit a sex difference. Investigators often use male rodents because they show metabolic disease better than females. Thus, females are not used precisely because of an acknowledged sex difference that represents an opportunity to understand novel factors reducing metabolic disease more in one sex than the other. The National Institutes of Health (NIH) mandate to consider sex as a biological variable in preclinical research places new demands on investigators and peer reviewers who often lack expertise in model systems and experimental paradigms used in the study of sex differences. This Perspective discusses experimental design and interpretation in studies addressing the mechanisms of sex differences in metabolic homeostasis and disease, using animal models and cells. We also highlight current limitations in research tools and attitudes that threaten to delay progress in studies of sex differences in basic animal research.

Mechanistic Pathways of Sex Differences in Cardiovascular Disease

Major differences between men and women exist in epidemiology, manifestation, pathophysiology, treatment, and outcome of cardiovascular diseases (CVD), such as coronary artery disease, pressure overload, hypertension, cardiomyopathy, and heart failure. Corresponding sex differences have been studied in a number of animal models, and mechanistic investigations have been undertaken to analyze the observed sex differences. We summarize the biological mechanisms of sex differences in CVD focusing on three main areas, i.e., genetic mechanisms, epigenetic mechanisms, as well as sex hormones and their receptors. We discuss relevant subtypes of sex hormone receptors, as well as genomic and nongenomic, activational and organizational effects of sex hormones. We describe the interaction of sex hormones with intracellular signaling relevant for cardiovascular cells and the cardiovascular system. Sex, sex hormones, and their receptors may affect a number of cellular processes by their synergistic action on multiple targets. We discuss in detail sex differences in organelle function and in biological processes. We conclude that there is a need for a more detailed understanding of sex differences and their underlying mechanisms, which holds the potential to design new drugs that target sex-specific cardiovascular mechanisms and affect phenotypes. The comparison of both sexes may lead to the identification of protective or maladaptive mechanisms in one sex that could serve as a novel therapeutic target in one sex or in both.