Sex differences in the pharmacokinetics of antidepressants: influence of female sex hormones and oral contraceptives

Utilizing national wastewater and sales data to derive and validate the correction factors of five common antidepressants for wastewater-based epidemiology

Monitoring antidepressant use is important for understanding mental health treatment status in populations and detecting potential misuse. Wastewater-based epidemiology (WBE) is a cost-effective approach to conduct such monitoring but requires valid correction factors (CFs) to accurately convert wastewater mass loads into consumption estimates. Most existing CFs are calculated from pharmacokinetic studies with small cohorts and are not specifically validated for WBE purposes. This study aimed to fill this knowledge gap by calibrating and validating the CFs for 5 commonly prescribed antidepressants. CFs were calibrated by dividing corresponding geo-located sales data by wastewater mass loads from 18 wastewater treatment plants in Australia for the same 3.5-year period. The refined CFs were 9.0 for fluoxetine, 6.4 for venlafaxine, and 25 for quetiapine. For the case of racemic citalopram and the pure S-enantiomer (escitalopram), individual CFs were proposed as 2.0 and 11, respectively. To validate their applicability, the new CFs were applied to independent datasets of wastewater samples collected in Belgium (2019 to 2022) and Australia (2020) and compared with sales data. The new calibrated CFs produced more accurate wastewater-based estimates of consumption for citalopram, escitalopram, fluoxetine, venlafaxine, and quetiapine, enhancing the capability of WBE in public health surveillance.

Sex Differences in the Pharmacokinetics of Cannabidiol and Metabolites Following Oral Administration of a Cannabidiol-Dominant Cannabis Oil in Healthy Adults

Introduction: Oral cannabidiol (CBD) product use is increasingly growing among women; however, there is a lack of data on sex differences in the pharmacokinetics (PKs) of CBD and its primary metabolites, 7-hydroxy-CBD (7-OH-CBD) and 7-carboxy-CBD (7-COOH-CBD), after repeated doses. Materials and Methods: The present study is a secondary analysis of data from a randomized, double-blind, placebo-controlled multiple-dose trial of a commercially available, CBD-dominant oral cannabis product. Healthy participants (n=17 males and 15 females) were randomized to receive 120 to 480 mg of CBD daily for 7 days. Dosing groups were pooled for all analyses due to sample size limitations. Analyses compared plasma PK parameters by sex, day, and sex×day. Results: For raw PK parameters for CBD and metabolites, there were no statistically significant effects of sex×day or sex (all p-values >0.05). For metabolite-to-parent ratios (MPRs) of AUC0-t, there were significant effects of the sex×day interactions for 7-OH-CBD (F=6.89, p=0.016) and 7-COOH-CBD (F=5.96, p=0.021). For 7-OH-CBD, follow-up analyses showed significant simple effects of day within females (t=4.13, p<0.001), but not within males (t=0.34, p=0.73), such that 7-OH-CBD MPRs increased significantly from day 1 to 7 for females, but not for males. For 7-COOH-CBD, follow-up analyses revealed significant simple effects of day within females (t=8.24, p<0.001) and males (t=5.20, p<0.001), therefore 7-COOH-CBD MPRs increased significantly from day 1 to 7 in both sexes, but the increase was significantly greater among females than among males. Within dosing days, there were no statistically significant simple effects of sex on MPRs of 7-OH-CBD or 7-COOH-CBD. Conclusions: Females exhibited greater relative exposure to CBD metabolites in plasma over time, which may reflect sex differences in CBD metabolism or elimination. Further research assessing the safety implications of higher relative exposure to CBD metabolites over longer periods of time is warranted to mirror typical consumer use patterns.

Changes in Psychotropic Drug Concentrations Across the Menstrual Cycle: A Pilot Study

BACKGROUND

The escalating prescription of psychopharmacological medications to women of reproductive age underscores the growing significance of sex-specific variations in pharmacotherapy. Despite this, clinical trials have largely overlooked these differences. Preliminary data indicate sex-specific variations in the neurobiology of affective disorders and in the metabolism, pharmacodynamics, and kinetics of therapeutic drugs. This underscores the imperative for a more nuanced exploration of menstrual cycle-dependent fluctuations in psychotropic drugs. This pilot study aimed to investigate drug and hormone fluctuations in female patients with affective disorders, aiming to enhance comprehension of the interplay between cycle-related hormone fluctuations and pharmacokinetics. The ultimate goal is to facilitate more effective and safer pharmacological therapy in the future.

METHODS

Blood samples were collected from 27 patients and 27 age-matched control participants at 3 distinct time points (early follicular phase, ovulation, and late luteal phase) during each menstrual cycle. Depressive and manic symptoms were assessed, and hormone concentrations were measured in the entire sample, while drug concentrations were assessed solely in the affective disorder sample using mass spectrometry.

RESULTS

Significant variations in drug concentration were observed throughout the menstrual cycle for bupropion, with a trend toward altered concentration for venlafaxine. Moreover, notable differences in hormone concentrations were identified between patients and controls, even after accounting for the impact of contraceptive use, diagnoses, and medication.

CONCLUSIONS

This pilot study reinforces previously reported data, underscoring the significance of sex-specific pharmacological therapy approaches. It provides further evidence supporting the interaction among sex hormones, drugs, and symptoms of affective disorders.

Novel rapid treatment options for adolescent depression

There is an urgent need for novel fast-acting antidepressants for adolescent treatment-resistant depression and/or suicidal risk, since the selective serotonin reuptake inhibitors that are clinically approved for that age (i.e., fluoxetine or escitalopram) take weeks to work. In this context, one of the main research lines of our group is to characterize at the preclinical level novel approaches for rapid-acting antidepressants for adolescence. The present review summarizes the potential use in adolescence of non-pharmacological options, such as neuromodulators (electroconvulsive therapy and other innovative types of brain stimulation), as well as pharmacological options, including consciousness-altering drugs (mainly ketamine but also classical psychedelics) and cannabinoids (i.e., cannabidiol), with promising fast-acting responses. Following a brief analytical explanation of adolescent depression, we present a general introduction for each therapeutical approach together with the clinical evidence supporting its potential beneficial use in adolescence (mainly extrapolated from prior successful examples for adults), to then report recent and/or ongoing preclinical studies that will aid in improving the inclusion of these therapies in the clinic, by considering potential sex-, age-, and dose-related differences, and/or other factors that might affect efficacy or long-term safety. Finally, we conclude the review by providing future avenues to maximize treatment response, including the need for more clinical studies and the importance of designing and/or testing novel treatment options that are safe and fast-acting for adolescent depression.

Practical solutions for including sex as a biological variable (SABV) in preclinical neuropsychopharmacological research

Recently, many funding agencies have released guidelines on the importance of considering sex as a biological variable (SABV) as an experimental factor, aiming to address sex differences and avoid possible sex biases to enhance the reproducibility and translational relevance of preclinical research. In neuroscience and pharmacology, the female sex is often omitted from experimental designs, with researchers generalizing male-driven outcomes to both sexes, risking a biased or limited understanding of disease mechanisms and thus potentially ineffective therapeutics. Herein, we describe key methodological aspects that should be considered when sex is factored into in vitro and in vivo experiments and provide practical knowledge for researchers to incorporate SABV into preclinical research. Both age and sex significantly influence biological and behavioral processes due to critical changes at different timepoints of development for males and females and due to hormonal fluctuations across the rodent lifespan. We show that including both sexes does not require larger sample sizes, and even if sex is included as an independent variable in the study design, a moderate increase in sample size is sufficient. Moreover, the importance of tracking hormone levels in both sexes and the differentiation between sex differences and sex-related strategy in behaviors are explained. Finally, the lack of robust data on how biological sex influences the pharmacokinetic (PK), pharmacodynamic (PD), or toxicological effects of various preclinically administered drugs to animals due to the exclusion of female animals is discussed, and methodological strategies to enhance the rigor and translational relevance of preclinical research are proposed.

Why do we keep ignoring sex in kidney disease?

Throughout the history of nephrology, little attention has been paid to the sex and gender differences in kidney disease. This lack of awareness prevents optimal diagnosis and management of kidney disease. In today's world of precision medicine, it is imperative to appreciate the differential factors regarding gender and kidney disease. This editorial summarizes the up-to-date literature regarding sex and gender differences in kidney disease and considers areas where knowledge is incomplete and where further research is needed. We address sex-specific effects on chronic kidney disease epidemiology; risks of dialysis underdosing and medication overdosing in women; unexplained loss of female sex advantage in life expectancy during dialysis, and impact of sex on diagnosis and management of genetic kidney disease. We also aim to highlight the impact of gender on kidney health and raise awareness of disparities that may be faced by women, and transgender and gender-diverse persons when a male-model approach is used by healthcare systems. By understanding the link between sex and kidney disease, kidney specialists can improve the care and outcomes of their patients. In addition, research on this topic can inform the development of targeted prevention and intervention strategies that address the specific needs and risk factors of different populations.

Aromatase inhibition and ketamine in rats: sex-differences in antidepressant-like efficacy

BACKGROUND

Ketamine has been recently approved to treat resistant depression; however preclinical studies showed sex differences in its efficacy. Sex steroids, such as estrogens and testosterone, both in the periphery and locally in the brain, are regarded as important modulators of these sex differences. Therefore, the present study evaluated how inhibiting the biosynthesis of estrogens with letrozole (an aromatase inhibitor) could affect the observed sex differences in ketamine's antidepressant-like-response.

METHODS

We performed several consecutive studies in adult Sprague-Dawley rats to evaluate potential sex differences in the antidepressant-like effects of ketamine (5 mg/kg, 7 days, i.p.), letrozole (1 mg/kg, 8 days, i.p.) and their combination (letrozole pre-treatment 3 h before ketamine). Acute and repeated antidepressant-like responses were ascertained in a series of behavioral tests (forced-swim, novelty-suppressed feeding, two-bottle choice for sucrose preference).

RESULTS

The main results proved clear sex differences in the antidepressant-like response induced by ketamine, which was observed following a repeated paradigm in adult male rats, but rendered inefficacious in female rats. Moreover, decreasing estrogens production with letrozole induced on itself an antidepressant-like response in female rats, while also increased ketamine's response in male rats (i.e., quicker response observed after only a single dose). Interestingly, both the antidepressant-like effects induced by ketamine in male rats or letrozole in female rats persisted over time up to 65 days post-treatment, suggesting long-term sex-directed benefits for these drugs.

CONCLUSIONS

The present results demonstrated a sex-specific role for aromatase inhibition with letrozole in the antidepressant-like response induced by ketamine in male rats. Moreover, letrozole itself presented as a potential antidepressant for females with persistent effects over time. Clearly, the production of estrogens is key in modulating, in a sex-specific manner, affective-like responses and thus deserve further studies.

Aromatase Inhibition and Electroconvulsive Seizures in Adolescent Rats: Antidepressant and Long-Term Cognitive Sex Differences

BACKGROUND

We recently showed sex differences in the antidepressant-like potential of electroconvulsive seizures (ECS) in adolescent rats; whereas it worked for male rats, it was inefficacious in females. Because sex steroids might be important modulators of these sex disparities, we evaluated the role of estrogens in the differential response induced by adolescent ECS. Moreover, given the literature suggesting certain cognitive sequelae from ECS exposure, we aimed at evaluating its long-term safety profile in adulthood.

METHODS

Adolescent Sprague-Dawley rats were pretreated with letrozole (1 mg/kg/day) or vehicle (1 mL/kg/day) for 8 days (i.p.) and treated during the last 5 days (3 hours later) with ECS (95 mA, 0.6 s, 100 Hz) or SHAM. Antidepressant-like responses were measured in the forced swim test, and long-term cognitive performance was assessed in the Barnes maze.

RESULTS

During adolescence, whereas ECS alone exerted an antidepressant-like response in male rats, its combination with letrozole permitted ECS to also induce efficacy in females. Moreover, adolescent ECS treatment improved cognitive performance in adulthood although exclusively in male rats.

CONCLUSIONS

Adolescent ECS demonstrated an antidepressant-like potential together with certain long-term beneficial cognitive effects but exclusively in male rats. For females, efficacy was restricted to a situation in which the biosynthesis of estrogens was reduced. Therefore, estrogens and/or testosterone levels play a crucial role in the sex disparities induced by ECS in Sprague-Dawley rats. Based on this study and on the literature supporting its safety, ECS should be encouraged for use in cases of treatment-resistant depression during adolescence, while adhering to sex-specific considerations.

The effect of curcumin on reserpine-induced depression-like behaviour in rats

The aim of this study was to construct an animal model of depression that reproduces the human clinical manifestation, to evaluate the possible benefits of curcumin (CUR) in the treatment of depression and to compare its effect with the effect of a classic antidepressant, escitalopram (ESC). The behavior of depressive-like animals induced by administration of 1.5 mg/kg i. p. reserpine (R), during 10 days (n = 24) was evaluated via the open field test (OFT) and elevated plus maze (EPM) compared to control animals (n = 24) treated with carboxymethylcellulose (CMC) used as a vehicle. On the 11th day, each group was divided into 3 subgroups (n = 8): control (CMC), CMC+CUR, CMC+ESC for group without depression and CMC+R, CMC+R+CUR, CMC+R+ESC for group with depression. CUR (150 mg/kg i.p.) and ESC (20 mg/kg i.p.) were intraperitoneally administrated for 21 days. The improvement in depressive behaviour was assessed by OFT, EPM and biochemical analysis on the 32nd day. The results demonstrated that R induced hypomotility and increased oxidative stress in the brain, but also in the serum of rats. CUR had an antioxidant effect in the brain without significant effect on depressive-like behaviour while ESC improved the hypomotility of the depressive rats.

Evaluation of Sex Differences in Preclinical Pharmacology Research: How Far Is Left to Go?

Until the last quarter of the 20th century, sex was not recognized as a variable in health research, nor was it believed to be a factor that could affect health and illness. Researchers preferred studying male models for a variety of reasons, such as simplicity, lower costs, hormone confounding effects, and fear of liability from perinatal exposure in case of pregnancy. Equitable representation is imperative for determining the safety, effectiveness, and tolerance of therapeutic agents for all consumers. Decades of female models' underrepresentation in preclinical studies has resulted in inequality in the understanding, diagnosis, and treatment of disease between the sexes. Sex bias has been highlighted as one of the contributing factors to the poor translation and replicability of preclinical research. There have been multiple calls for action, and the inclusion of sex as a biological variable is increasingly supported. However, although there has been substantial progress in the efforts to include more female models in preclinical studies, disparities today remain. In the present review, we consider the current standard practice of the preclinical research setting, why the sex bias exists, why there is the need to include female models, and what risks may arise from continuing this exclusion from experimental design.

Intersection of Sex and Depression: Pathogenesis, Presentation, and Treatments

Major Depressive Disorder (MDD) is a highly prevalent, debilitating disorder. According to the World Health Organization, approximately 5% of adults suffer from depression worldwide and more women than men are affected. Yet, we have a very limited understanding of the pathogenesis of the disease, how sex and genetics influence the pathophenotype of MDD, and how they contribute to the responses to pharmacological treatment. This chapter addresses key theories about the etiology of depression, the variations in epidemiology and presentation, and the treatment options with respect to sex and gender. Additionally, we discuss the emerging wave of treatment modalities, diagnosis, and research focusing on MDD.

Se(XY) matters: the importance of incorporating sex in microphysiological models

The development of microphysiological models is currently at the forefront of preclinical research. Although these 3D tissue models are being developed to mimic physiological organ function and diseases, which are often sexually dimorphic, sex is usually neglected as a biological variable. For decades, national research agencies have required government-funded clinical trials to include both male and female participants as a means of eliminating male bias. However, this is not the case in preclinical trials, which have been shown to favor male rodents in animal studies and male cell types in in vitro studies. In this Opinion, we highlight the importance of considering sex as a biological variable and outline five approaches for incorporating sex-specific features into current microphysiological models.

Premenstrual exacerbation of mental health disorders: a systematic review of prospective studies

Mental health disorders can be exacerbated during periods of hormonal fluctuation (e.g. pregnancy, menopause), and the risk factors for sensitivity to these fluctuations are similar to those of mental disorders (e.g. trauma). However, the extent to which hormonal fluctuations during the menstrual cycle impact symptoms of preexisting mental disorders remains unclear. Prospective methodology is considered the gold standard for measuring symptoms across the menstrual cycle. Thus, the aim of the review was to address this knowledge gap by summarising all available studies prospectively measuring symptoms of mental disorders across the menstrual cycle. A systematic review with narrative synthesis was conducted; meta-analysis was precluded due to methodological heterogeneity of included studies. Electronic databases MEDLINE, Embase, PyschINFO and CINAHL were systematically searched from inception. Risk of bias for individual studies was assessed using a modified version of the Newcastle-Ottawa Scale. The search identified 629 studies from which 35 met inclusion criteria. There was clear evidence of symptom exacerbation during the perimenstrual phase for psychotic disorders, panic disorder, eating disorders, depression and borderline personality disorder. Less consistent evidence was found for anxiety, and a different pattern of symptom exacerbation was observed in bipolar disorder. Sample size and methodology varied considerably amongst studies. Overall, there was mixed evidence for perimenstrual exacerbation across mental disorders, which could be partly explained by methodological limitations of the studies. However, hormonal fluctuations during the menstrual cycle may exacerbate psychiatric symptoms in a subgroup of individuals who are hormone sensitive.

The effects of Vilazodone, YL-0919 and Vortioxetine in hemiparkinsonian rats

Parkinson's disease is a neurodegenerative disease often characterized by motor deficits and most commonly treated with dopamine replacement therapy. Despite its benefits, chronic use of L-DOPA results in abnormal involuntary movements known as L-DOPA-induced dyskinesia. Growing evidence shows that with burgeoning dopamine cell loss, neuroplasticity in the serotonin system leads to the development of L-DOPA-induced dyskinesia through the unregulated uptake, conversion, and release of L-DOPA-derived dopamine into the striatum. Previous studies have shown that coincident 5-HT_1A agonism and serotonin transporter inhibition may have anti-dyskinetic potential. Despite this, few studies have explicitly focused on targeting both 5-HT_1A and the serotonin transporter. The present study compares the 5-HT compounds Vilazodone, YL-0919, and Vortioxetine which purportedly work as simultaneous 5-HT_1A receptor agonists and SERT blockers. To do so, adult female Sprague Dawley rats were rendered hemiparkinsonian and treated daily for two weeks with L-DOPA to produce stable dyskinesia. The abnormal involuntary movements and forehand adjusting step tests were utilized as measurements for L-DOPA-induced dyskinesia and motor performance in a within-subjects design. Lesion efficacy was determined by analysis of striatal monoamines via high-performance liquid chromatography. Compounds selective for 5-HT_1A/SERT target sites including Vilazodone and Vortioxetine significantly reduced L-DOPA-induced dyskinesia without compromising L-DOPA pro-motor efficacy. In contrast, YL-0919 failed to reduce L-DOPA-induced dyskinesia, with no effects on L-DOPA-related improvements. Collectively, this work supports pharmacological targeting of 5-HT_1A/SERT to reduce L-DOPA-induced dyskinesia. Additionally, this further provides evidence for Vilazodone and Vortioxetine, FDA-approved compounds, as potential adjunct therapeutics for L-DOPA-induced dyskinesia management in Parkinson's patients.

Sex-Related Differences in Pharmacological Response to CNS Drugs: A Narrative Review

In the last decades, both animal and human studies have neglected female subjects with the aim of evading a theorized intricacy of feminine hormonal status. However, clinical experience proves that pharmacological response may vary between the two sexes since pathophysiological dissimilarities between men and women significantly influence the pharmacokinetics and pharmacodynamics of drugs. Sex-related differences in central nervous system (CNS) medication are particularly challenging to assess due to the complexity of disease manifestation, drugs’ intricate mechanisms of action, and lack of trustworthy means of evaluating the clinical response to medication. Although many studies showed contrary results, it appears to be a general tendency towards a certain sex-related difference in each pharmacological class. Broadly, opioids seem to produce better analgesia in women especially when they are administered for a prolonged period of time. On the other hand, respiratory and gastrointestinal adverse drug reactions (ADRs) following morphine therapy are more prevalent among female patients. Regarding antidepressants, studies suggest that males might respond better to tricyclic antidepressants (TCAs), whereas females prefer selective serotonin reuptake inhibitors (SSRI), probably due to their tolerance to particular ADRs. In general, studies missed spotting any significant sex-related differences in the therapeutic effect of antiepileptic drugs (AED), but ADRs have sex variations in conjunction with sex hormones’ metabolism. On the subject of antipsychotic therapy, women appear to have a superior response to this pharmacological class, although there are also studies claiming the opposite. However, it seems that reported sex-related differences regarding ADRs are steadier: women are more at risk of developing various side effects, such as metabolic dysfunctions, cardiovascular disorders, and hyperprolactinemia. Taking all of the above into account, it seems that response to CNS drugs might be occasionally influenced by sex as a biological variable. Nonetheless, although for each pharmacological class, studies generally converge to a certain pattern, opposite outcomes are standing in the way of a clear consensus. Hence, the fact that so many studies are yielding conflicting results emphasizes once again the need to address sex-related differences in pharmacological response to drugs.

Towards better care for women with schizophrenia-spectrum disorders

Women with a schizophrenia-spectrum disorder (SSD) have a better clinical profile than do men at the start of their illness but progress to the same state within the first few years of living with SSD. There are benefits to be gained across different areas in the care currently offered to women with psychosis. An important point for improvement is the early detection of female-specific signs of a first episode of psychosis, to shorten the duration of untreated psychosis, with prompt access to early intervention services. Special attention should be paid to sexual health, and to any history of childhood trauma. Antipsychotics require dosing and prescription tailored to the female physiology that consider hormonal life phases such as menopause. Switching to prolactin-sparing medications can benefit both mental and somatic health. Finally, hormone replacement therapy should be considered for postmenopausal women. By providing female-specific care, women with schizophrenia-spectrum disorders will have optimal chances to fare well.

Sex differences in the blood-brain barrier: Implications for mental health

Prevalence of mental disorders, including major depressive disorder (MDD), bipolar disorder (BD) and schizophrenia (SZ) are increasing at alarming rates in our societies. Growing evidence points toward major sex differences in these conditions, and high rates of treatment resistance support the need to consider novel biological mechanisms outside of neuronal function to gain mechanistic insights that could lead to innovative therapies. Blood-brain barrier alterations have been reported in MDD, BD and SZ. Here, we provide an overview of sex-specific immune, endocrine, vascular and transcriptional-mediated changes that could affect neurovascular integrity and possibly contribute to the pathogenesis of mental disorders. We also identify pitfalls in current literature and highlight promising vascular biomarkers. Better understanding of how these adaptations can contribute to mental health status is essential not only in the context of MDD, BD and SZ but also cardiovascular diseases and stroke which are associated with higher prevalence of these conditions.

Antipsychotic medication for women with schizophrenia spectrum disorders

There are significant differences between men and women in the efficacy and tolerability of antipsychotic drugs. Here, we provide a comprehensive overview of what is currently known about the pharmacokinetics and pharmacodynamics of antipsychotics in women with schizophrenia spectrum disorders (SSDs) and translate these insights into considerations for clinical practice. Slower drug absorption, metabolism and excretion in women all lead to higher plasma levels, which increase the risk for side-effects. Moreover, women reach higher dopamine receptor occupancy compared to men at similar serum levels, since oestrogens increase dopamine sensitivity. As current treatment guidelines are based on studies predominantly conducted in men, women are likely to be overmedicated by default. The risk of overmedicating generally increases when sex hormone levels are high (e.g. during ovulation and gestation), whereas higher doses may be required during low-hormonal phases (e.g. during menstruation and menopause). For premenopausal women, with the exceptions of quetiapine and lurasidone, doses of antipsychotics should be lower with largest adjustments required for olanzapine. Clinicians should be wary of side-effects that are particularly harmful in women, such as hyperprolactinaemia which can cause oestrogen deficiency and metabolic symptoms that may cause cardiovascular diseases. Given the protective effects of oestrogens on the course of SSD, oestrogen replacement therapy should be considered for postmenopausal patients, who are more vulnerable to side-effects and yet require higher dosages of most antipsychotics to reach similar efficacy. In conclusion, there is a need for tailored, female-specific prescription guidelines, which take into account adjustments required across different phases of life.

The Impact of Hormonal Contraceptive Use on Serotonergic Neurotransmission and Antidepressant Treatment Response: Results From the NeuroPharm 1 Study

BACKGROUND

Hormonal contraceptive (HC) use has been associated with an increased risk of developing a depressive episode. This might be related to HC's effect on the serotonergic brain system as suggested by recent cross-sectional data from our group, which show that healthy oral contraceptive (OC) users relative to non-users have lower cerebral serotonin 4 receptor (5-HT4R) levels. Here, we determine if cerebral 5-HT4R binding differs between HC non-users, OC users, and hormonal intrauterine device (HIUD) users among women with an untreated depressive episode. Also, we test if antidepressant drug treatment response and its association with pre-treatment 5-HT4R binding depends on HC status.

METHODS

[¹¹C]-SB207145 Positron Emission Tomography imaging data from the NeuroPharm-NP1 Study (NCT02869035) were available from 59 depressed premenopausal women, of which 26 used OCs and 10 used HIUDs. The participants were treated with escitalopram. Treatment response was measured as the relative change in the Hamilton Depression Rating Scale 6 items (rΔHAMD₆) from baseline to week eight. Latent variable models were used to evaluate the association between global 5-HT4R binding and OC and HIUD use as well as rΔHAMD₆.

RESULTS

We found no evidence of a difference in global 5-HT4R binding between depressed HC users and non-users (p≥0.51). A significant crossover interaction (p=0.02) was observed between non-users and OC users in the association between baseline global 5-HT4R binding and week eight rΔHAMD₆; OC users had 3-4% lower binding compared to non-users for every 10% percent less improvement in HAMD₆. Within the groups, we observed a trend towards a positive association in non-users (p_adj=0.10) and a negative association in OC users (p_adj=0.07). We found no strong evidence of a difference in treatment response between the groups (p=0.13).

CONCLUSIONS

We found no difference in 5-HT4R binding between HC users vs. non-users in depressed women, however, it seemed that 5-HT4R settings differed qualitatively in their relation to antidepressant drug treatment response between OC users and non-users. From this we speculate that depressed OC users constitutes a special serotonin subtype of depression, which might have implications for antidepressant drug treatment response.

Premenstrual Exacerbations of Mood Disorders: Findings and Knowledge Gaps

PURPOSE OF REVIEW

In contrast to premenstrual dysphoric disorder (PMDD), premenstrual exacerbations (PMEs) of ongoing mood disorders are understudied. The aim of this review is to describe diagnostic issues, epidemiology, underlying mechanisms, and treatment for PME in unipolar depression and bipolar disorder, and to discuss clinical and research implications.

RECENT FINDINGS

Community-based and clinical studies estimate that in women with mood disorders around 60% report PME, while some women with bipolar disorder also show symptom exacerbations around ovulation. In general, PME predicts a more severe illness course and an increased burden. While heightened sensitivity to fluctuations of sex hormone levels across the menstrual cycle appears to contribute to PME and PMDD, the overlap of their underlying biological mechanisms remains unclear. Beneficial treatments for PMDD show less or no efficacy in PME. Pharmacological treatments for PME in mood disorders predominantly seem to profit from adjustable augmentation of treatment dosages during the luteal phase for the underlying disorder. However, the evidence is sparse and mainly based on earlier small studies and case reports. Previous research is mainly limited by the lack of a clear differentiation between PME and PMDD comorbidity with mood disorders. More systematic research with uniformly defined and prospectively assessed subgroups of PME in larger epidemiological and clinical samples is needed to receive reliable prevalence estimates and information on the clinical impact of PME of mood disorders, and to uncover underlying mechanisms. In addition, larger randomized controlled trials are warranted to identify efficacious pharmacological and psychotherapeutic treatments for affected women.

Let's talk about sex: Differences in drug therapy in males and females

Professor Henry Higgins in My Fair Lady said, 'Why can't a woman be more like a man?' Perhaps unintended, such narration extends to the reality of current drug development. A clear sex-gap exists in pharmaceutical research spanning from preclinical studies, clinical trials to post-marketing surveillance with a bias towards males. Consequently, women experience adverse drug reactions from approved drug products more often than men. Distinct differences in pharmaceutical response across drug classes and the lack of understanding of disease pathophysiology also exists between the sexes, often leading to suboptimal drug therapy in women. This review explores the influence of sex as a biological variable in drug delivery, pharmacokinetic response and overall efficacy in the context of pharmaceutical research and practice in the clinic. Prospective recommendations are provided to guide researchers towards the consideration of sex differences in methodologies and analyses. The promotion of disaggregating data according to sex to strengthen scientific rigour, encouraging innovation through the personalisation of medicines and adopting machine learning algorithms is vital for optimised drug development in the sexes and population health equity.

Sex hormones and immune system: A possible interplay in affective disorders? A systematic review

BACKGROUND

Sex hormones and the immune system may play a key role in sex differences in affective disorders. The understanding of their interplay may lead to the detection of new sex-specific tailored therapeutic approaches. The aim of this systematic review is to summarise the evidence supporting a possible association between sex hormones and inflammatory biomarkers in people with affective disorders.

METHODS

A systematic search of the literature published until January 2021 was conducted on PubMed database. The initial search identified a total of 1259 studies; 20 studies investigating inflammatory biomarkers and sex hormones in patients exhibiting depressive symptoms were included: 10 studies focused on patients with affective disorders, and 10 studies focused on women in menopause or in the post-partum period exhibiting depressive symptoms.

RESULTS

Testosterone and exogenous female sex hormones may play protective roles through their modulation of the immune system, respectively, in male patients with bipolar disorder and in peri-/post-menopausal women with depression.

LIMITATIONS

The main limitations are the paucity of studies investigating both sex hormones and immune biomarkers, the lack of statistical analyses exploring specifically the association between these two classes of biomarkers, and the great heterogeneity between the participants' samples in the studies.

CONCLUSION

This review highlights the need to investigate the interplay between sex hormones and immune system in affective disorders. The inconsistent or incomplete evidence may be improved by studies in patients with moderate-high inflammatory levels that specifically evaluate the relationship between sex hormones and the immune system.

Sex hormone levels in females of different ages suffering from depression

Background

There are only a few studies on sex hormones in females of different ages suffering from depression, and their conclusions are not uniform until now. This study aimed to investigate the correlation between the severity of depression in females and factors such as sex hormones and differences in sex hormone levels in females of different ages, exploring variations after treatment.

Methods

A total of 169 females with depression were selected and divided into the first-episode (91 cases) and recurrent (78 cases) groups. Then, on the basis of their age, the first-episode patients were divided into the young (48 cases, age < 45 years), perimenopausal (20 cases, 45–55 years), and elderly groups (23 cases, age > 55 years); the patients with recurrent depression were classified into the young (37 cases, age < 45 years), perimenopausal (19 cases, 45–55 years), and elderly groups (22 cases, age > 55 years). The patients were assessed in accordance with the International Classification of Diseases of mental and behavioral disorders. The serum progesterone, prolactin, estradiol, and testosterone levels in the patients were measured, and differences in sex hormone levels of the groups were analyzed.

Results

The estradiol level was negatively correlated with age and the prolactin level was positively correlated with occupation. The severity of depression in females was found to be negatively correlated with age. The serum progesterone and estradiol levels in the young group were significantly higher than those in the elderly group, regardless of the first episode or recurrence. Estradiol levels in the perimenopausal and elderly groups with first-episode depression were significantly higher than those in the same group with recurrent depression. However, there was no significant difference in the serum progesterone, prolactin, estradiol, and testosterone levels in the recurrent group before and after treatment.

Conclusions

Sex hormone levels, especially estradiol, varied among females of different ages suffering from depression. Recurrent depression also has a certain effect on sex hormone levels in females. Not only should the age and relapse be considered when studying the sex hormone levels of females with depression, but also attention should be paid to whether the patients have used antidepressants before their sexual hormonal testing.

Antidepressants' effects on testosterone and estrogens: What do we know?

Various antidepressants are commonly used to treat depression and anxiety disorders, and sex differences have been identified in their efficacy and side effects. Steroids, such as estrogens and testosterone, both in the periphery and locally in the brain, are regarded as important modulators of these sex differences. This review presents published data from preclinical and clinical studies that measure testosterone and estrogen level changes during and/or after acute or chronic administration of different antidepressants. The majority of studies show an interaction between sex hormones and antidepressants on sexual function and behavior, or in depressive symptom alleviation. However, most of the studies omit to investigate antidepressants' effects on circulating levels of gonadal hormones. From data reviewed herein, it is evident that most antidepressants can influence testosterone and estrogen levels. Still, the evidence is conflicting with some studies showing an increase, others decrease or no effect. Most studies are conducted in male animals or humans, underscoring the importance of considering sex as an important variable in such investigations, especially as depression and anxiety disorders are more common in women than men. Therefore, research is needed to elucidate the extent to which antidepressants can influence both peripheral and brain levels of testosterone and estrogens, in males and females, and whether this impacts the effectiveness or side effects of antidepressants.

Sex-specific Association of Antipsychotic-induced Weight Gain and Treatment Response for Antipsychotic-Naive First Episode Schizophrenia Patients: A Prospective 8-week Longitudinal Study

BACKGROUND

Patients with antipsychotic-naïve first-episode (ANFE) schizophrenia (SZ) can help clarify many confounding factors in determining sex differences in antipsychotic drug induced weight gain and its association with symptom improvement.

METHODS

This 8-week longitudinal trial of ANFE patients with SZ enrolled 526 patients and 313 healthy controls. We evaluated bodyweight and the efficacy of antipsychotics on the Positive and Negative Syndrome Scale (PANSS) at baseline and at the end of week 8.

RESULTS

Males and females after treatment showed no sex difference in weight gain, BMI increase, and percentage of weight gain. However, at baseline, male patients had more positive symptoms than female patients, and decreases in positive symptoms, general psychopathology, and total PANSS scores were less in male than female patients. Adjusting for confounding factors using multiple linear regression confirmed that weight gain was significantly associated with these decreases in PANSS symptoms only in men not women.

CONCLUSIONS

The relationship between weight gain and symptom reduction after 8 weeks of antipsychotic treatment exists only in male patients with ANFE SZ and not in female patients.

Gender-specific approach in psychiatric diseases: Because sex matters

In both animals and human beings, males and females differ in their genetic background and hormonally driven behaviour and show sex-related differences in brain activity and response to internal and external stimuli. Gender-specific medicine has been a neglected dimension of medicine for long time, and only in the last three decades it is receiving the due scientific and clinical attention. Research has recently begun to identify factors that could provide a neurobiological basis for gender-based differences in health and disease and to point to gonadal hormones as important determinants of male-female differences. Animal studies have been of great help in understanding factors contributing to sex-dependent differences and sex hormones action. Here we review and discuss evidence provided by clinical and animal studies in the last two decades showing gender (in humans) and sex (in animals) differences in selected psychiatric disorders, namely eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder), schizophrenia, mood disorders (anxiety, depression, obsessive-compulsive disorder) and neurodevelopmental disorders (autism spectrum disorders, attention-deficit/hyperactivity disorder).

Gender Differences in the First-Year Antipsychotic Treatment for Chinese First-Episode Schizophrenia

OBJECTIVE

To investigate the gender differences in the efficacy and side effects of three frequently used antipsychotic medicines (risperidone, olanzapine, aripiprazole) for patients with first-episode schizophrenia during the first year of treatment.

METHODS

A total of 569 patients with first-episode schizophrenia were randomly assigned to risperidone, olanzapine, and aripiprazole groups. All patients were treated according to their actual clinical needs. Clinical efficacies were assessed by the Positive and Negative Symptom Scale (PANSS) and side effects were assessed by the Udvalg for Kliniske Undersogelser Side-Effect scale (UKU). All assessments were completed at baseline and at 1, 2, 3, 6, 9, and 12 months.

RESULTS

Males had higher baseline PANSS total scores and PANSS negative and general pathological scores. No significant interactions were found between treatment time and gender in psychopathology improvements in all three groups. In the end of the first year, female patients receiving risperidone reported more dermatological symptoms (rashes) than males, female patients receiving olanzapine reported more autonomic side effects and dermatological symptoms than males, and female patients receiving aripiprazole reported more psychotic side effects than males.

CONCLUSION

Gender differences exhibited in response to antipsychotic treatments for Chinese patients with first-episode schizophrenia. After the first year of antipsychotic treatment, drug-related side effects were more likely presented in female patients than male patients.

Do we need sex-oriented clinical practice guidelines for the treatment of schizophrenia?

PURPOSE OF REVIEW

Clinical practice guidelines (CPGs) do not usually offer a sex-specific approach for the management of schizophrenia. With this narrative review, we aim to give an integrated and synthesized overview of the current state of knowledge regarding sex-specific aspects in schizophrenia and how this topic may be adapted in the development of CPGs.

RECENT FINDINGS

Recent studies further suggest sex-specific differences in epidemiologic features, the course of illness, underlying pathomechanisms, response likelihood to antipsychotic medication and differences in tolerability. Beyond this, selective estrogen receptor modulators like raloxifene have shown beneficial effects on symptom severity and cognition in women with schizophrenia.

SUMMARY

Sex-specific aspects can already be integrated in clinical guideline recommendations, especially with regard to efficacy and tolerability of antipsychotic treatment. Moreover, these aspects may be used for an individual risk-stratification. Recent studies provide evidence supporting the hypothesis of sex-specific modulation in schizophrenia and build the groundwork for sex-specific novel treatment options. However, there remains a clear need for additional studies focusing on women with schizophrenia to substantiate current findings.

The role of sex and gender in anxiety disorders: Being scared "like a girl"?

Anxiety disorders are among the most prevalent mental disorders, and women are at much higher risk to develop an(y) anxiety disorder. Women seem to experience more severe and long-lasting symptoms than men. Sex differences regarding etiology can be best understood from a vulnerability-stress perspective. A different exposure to psychosocial stressors and an increased biologic and/or psychologic vulnerability toward anxiety in women may contribute to the sex differences in anxiety disorders. Evidently, these findings have implications for both the diagnosis and treatment of patients with anxiety disorders. Therapists should be aware of gender bias during the diagnostic process and be sensitive for self-reporting bias (i.e., the reluctance to report "female-like" symptoms by men). Research on sex differences with respect to treatment is lacking and gender-related knowledge has rarely been integrated into clinical interventions. Interventions aimed at transdiagnostic factors that have been shown to relate to sex differences in anxiety seem rather promising and have the potential to enhance the care for both men and women with anxiety disorders.

Antidepressant effects of ketamine on depression-related phenotypes and dopamine dysfunction in rodent models of stress

Depression, the most prevalent psychiatric disorder, is characterized by increased negative affect (i.e. depressed mood) and reduced positive affect (i.e. anhedonia). Stress is a risk factor for depression in humans, and animal models of chronic stress are typically used to study neurobehavioral alterations relevant to depression. Common behavioral outcomes in rodent models of chronic stress include anhedonia, social dysfunction and behavioral despair. For example, chronically stressed rodents exhibit reduced reward preference, as measured by a loss of preference for sucrose solutions and time spent interacting with a novel conspecific, while also exhibiting less time struggling against inescapable stressors (e.g. forced swim, tail suspension). In both humans and rodents, anhedonia is associated with dysfunction of the dopamine (DA) system. Unlike traditional antidepressants, which are limited by inadequate efficacy and delayed therapeutic response, acute ketamine administration rapidly alleviates depressive symptoms in humans and reverses stress-induced changes in animal models. These effects are partially mediated via actions on the DA system. This review summarizes the clinical effects of ketamine, the neurobiological underpinnings of depression with a focus on DA dysfunction, as well as antidepressant effects of ketamine on depression-related endophenotypes (i.e. anhedonia, despair) and ventral tegmental area (VTA) activity in rodent models of repeated stress. Moreover, we discuss evidence regarding sex differences in ketamine's antidepressant effects, wherein females appear to be more sensitive to lower dose ketamine, as well as novel findings suggesting that ketamine has prophylactic effects with regard to protection against the neurobehavioral impact of future stressors.

Sex differences in fear extinction

Despite the exponential increase in fear research during the last years, few studies have included female subjects in their design. The need to include females arises from the knowledge gap of mechanistic processes underlying the behavioral and neural differences observed in fear extinction. Moreover, the exact contribution of sex and hormones in relation to learning and behavior is still largely unknown. Insights from this field could be beneficial as fear-related disorders are twice as prevalent in women compared to men. Here, we review an up-to-date summary of animal and human studies in adulthood that report sex differences in fear extinction from a structural and functional approach. Furthermore, we describe how these factors could contribute to the observed sex differences in fear extinction during normal and pathological conditions.

Sex differences in depression: Insights from clinical and preclinical studies

Depression represents a global mental health concern, and disproportionally affects women as they are twice more likely to be diagnosed than men. In this review, we provide a summary of evidence to support the notion that differences in depression between men and women span multiple facets of the disease, including epidemiology, symptomology, treatment, and pathophysiology. Through a lens of biological sex, we overview depression-related transcriptional patterns, changes in neuroanatomy and neuroplasticity, and immune signatures. We acknowledge the unique physiological and behavioral demands of pregnancy and motherhood by devoting special attention to depression occurring in the peripartum period. Specifically, we discuss issues surrounding the presentation, time course, treatment, and neurobiology of peripartum depression. We write this review with the intention of highlighting the encouraging advancements in our understanding of sex differences in depression, while underscoring the gaps that remain. A more systematic consideration of biological sex as a variable in depression research will be critical in the discovery and development of pharmacotherapies that are efficacious for both men and women.

Women's Psychiatry

Brain disorders and mental diseases, in particular, are common and considered as a top global health challenge for the twenty-first century. Interestingly, women suffer more frequently from mental disorders than men. Moreover, women may respond to psychotropic drugs differently than men, and, through their lifespan, they endure sex-orientated social stressors. In this chapter, we present how women may differ in the development and manifestation of mental health issues and how they differ from men in pharmacokinetics and pharmacodynamics. We discuss issues in clinical trials regarding women participation, issues in the use of psychotropic medications in pregnancy, and challenges that psychiatry faces as a result of the wider use of contraceptives, of childbearing at older age, and of menopause. Such issues, among others, demand further women-oriented psychiatric research that can improve the care for women during the course of their lives. Indeed, despite all these known sex differences, psychiatry for both men and women patients uses the same approach. Thereby, a modified paradigm for women's psychiatry, which takes into account all these differences, emerges as a necessity, and psychiatric research should take more vigorously into account sex differences.

Sex differences in antidepressant efficacy

Sex differences have been observed across many psychiatric diseases, especially mood disorders. For major depression, the most prevalent psychiatric disorder, females show a roughly two-fold greater risk as compared to males. Depression is sexually dimorphic with males and females exhibiting differences in clinical presentation, course, and response to antidepressant treatment. In this review, we first discuss sex differences observed in depressed patients, as well as animal models that reveal potential underlying mechanisms. We then discuss antidepressant treatments including their proposed mechanism of action and sex differences observed in treatment response. We include possible mechanisms underlying these sex differences with particular focus on synaptic transmission.

Menstrual cycle rhythmicity: metabolic patterns in healthy women

The menstrual cycle is an essential life rhythm governed by interacting levels of progesterone, estradiol, follicular stimulating, and luteinizing hormones. To study metabolic changes, biofluids were collected at four timepoints in the menstrual cycle from 34 healthy, premenopausal women. Serum hormones, urinary luteinizing hormone and self-reported menstrual cycle timing were used for a 5-phase cycle classification. Plasma and urine were analyzed using LC-MS and GC-MS for metabolomics and lipidomics; serum for clinical chemistries; and plasma for B vitamins using HPLC-FLD. Of 397 metabolites and micronutrients tested, 208 were significantly (p < 0.05) changed and 71 reached the FDR 0.20 threshold showing rhythmicity in neurotransmitter precursors, glutathione metabolism, the urea cycle, 4-pyridoxic acid, and 25-OH vitamin D. In total, 39 amino acids and derivatives and 18 lipid species decreased (FDR < 0.20) in the luteal phase, possibly indicative of an anabolic state during the progesterone peak and recovery during menstruation and the follicular phase. The reduced metabolite levels observed may represent a time of vulnerability to hormone related health issues such as PMS and PMDD, in the setting of a healthy, rhythmic state. These results provide a foundation for further research on cyclic differences in nutrient-related metabolites and may form the basis of novel nutrition strategies for women.

The impact of sex as a biological variable in the search for novel antidepressants

A roadblock to successful treatment for anxiety and depression is the high proportion of individuals that do not respond to existing treatments. Different underlying neurobiological mechanisms may drive similar symptoms, so a more personalized approach to treatment could be more successful. There is increasing evidence that sex is an important biological variable modulating efficacy of antidepressants and anxiolytics. We review evidence for sex-specific effects of traditional monoamine based antidepressants and newer pharmaceuticals targeting kappa opioid receptors (KOR), oxytocin receptors (OTR), and N-methyl-D-aspartate receptors (ketamine). In some cases, similar behavioral effects are observed in both sexes while in other cases strong sex-specific effects are observed. Most intriguing are cases such as ketamine which has similar behavioral effects in males and females, perhaps through sex-specific neurobiological mechanisms. These results show how essential it is to include both males and females in both clinical and preclinical evaluations of novel antidepressants and anxiolytics.

Treatment of Depression in Women

Women are more likely than men to experience depression throughout the life span. Sex differences in neurochemistry and brain structure, as well as societal factors may contribute to women's increased likelihood of depression. Pharmacological research targeting depression has historically excluded women, leading to a knowledge gap regarding effective antidepressant treatment in women. Antidepressant pharmacokinetics and pharmacodynamics are clearly different in men and women, necessitating a thoughtful approach to their prescription and management. Hormone changes associated with the menstrual cycle, pregnancy, and menopause also contribute to differences in depression and effective antidepressant use in women. Finally, it is important to consider potential interactions between antidepressant drugs and medications specifically used by women (oral contraceptives, tamoxifen, and estrogen).

The effects of six-day SSRI administration on diurnal cortisol secretion in healthy volunteers

RATIONALE

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been widely reported in depression, and evidence suggests that selective serotonin reuptake inhibitors (SSRIs) might exert their therapeutic effects through altering cortisol secretion.

OBJECTIVE

This study assessed the effects of SSRI administration on diurnal cortisol secretion in healthy volunteers.

METHODS

Sixty-four healthy men and women were randomised to receive either 10 mg escitalopram or placebo for six days in a double-blind fashion. On day six of medication, saliva samples were obtained at home for measurement of diurnal cortisol parameters (cortisol slope, cortisol awakening response, total daily cortisol output).

RESULTS

Women receiving escitalopram had significantly steeper cortisol slopes across the day compared with those receiving placebo (F(1, 36) = 7.54, p = 0.009). This alteration in cortisol slope was driven by increases in waking cortisol levels (F(1, 35) = 9.21, p = 0.005). Escitalopram did not have any significant effect on the cortisol awakening response or the total daily cortisol output.

CONCLUSIONS

Flattened cortisol slopes have been seen in depression. The results of this study suggest that escitalopram might exert its therapeutic effect in women in part through correction of a flattened diurnal cortisol rhythm.

Use of Selective Serotonin Reuptake Inhibitors and Bone Mineral Density Change: A Population-Based Longitudinal Study in Middle-Aged and Elderly Individuals

BACKGROUND

Longitudinal studies showed conflicting results regarding the association between use of selective serotonin reuptake inhibitors (SSRIs) and bone mineral density (BMD). Therefore, we investigate the association between-duration of-SSRI use and BMD, and change in BMD ([INCREMENT]BMD).

METHODS

Data from the population-based Rotterdam Study cohort (1991-2008) were used. In total, 4915 men and 5831 postmenopausal women, aged 45 years and older, were included, having measurement visits at 4- to 5-year intervals. Multivariable linear mixed models were applied to examine the association between SSRI use, based on pharmacy records, duration of SSRI use, and repeated measures of BMD, and changes in BMD, compared with nonuse. Femoral neck BMD (grams per centimeters squared) was measured at 4 visits, comprising 19,861 BMD measurements. Three [INCREMENT]BMD periods were examined, comprising 7897 [INCREMENT]BMD values. Change in BMD was expressed in the annual percentage [INCREMENT]BMD between 2 consecutive visits.

RESULTS

In men and women, we observed no association between SSRI and BMD when compared with nonuse (women: mean difference, 0.007 g/cm; 95% confidence interval, -0.002 to 0.017; P = 0.123). We did not find an association between duration of SSRI use and [INCREMENT]BMD (women: annual percentage change, -0.081; 95% confidence interval, -0.196 to 0.033; P = 0.164).

CONCLUSIONS

In conclusion, use of SSRIs is not associated with BMD or [INCREMENT]BMD, after taking duration of treatment into account, in middle-aged and elderly individuals. Therefore, our results question previously raised concerns on the adverse effects of SSRIs on BMD.

Why are women so vulnerable to anxiety, trauma-related and stress-related disorders? The potential role of sex hormones

Increased prevalence, severity, and burden of anxiety, trauma-related and stress-related disorders in women compared with men has been well documented. Evidence from a variety of fields has emerged suggesting that sex hormones, particularly oestradiol and progesterone, play a significant part in generation of these sex differences. In this Series paper, we aim to integrate the literature reporting on the effects of sex hormones on biological, behavioural, and cognitive pathways, to propose two broad mechanisms by which oestradiol and progesterone influence sex differences in anxiety disorders: augmentation of vulnerability factors associated with anxiety disorder development; and facilitation of the maintenance of anxious symptoms post-development. The implications for future research, along with novel approaches to psychological and pharmacological treatment of anxiety disorders, are also considered.

An integrative review of methylation at the serotonin transporter gene and its dialogue with environmental risk factors, psychopathology and 5-HTTLPR

Gene-environment (G×E) interactions have largely been regarded as the root of many complex disorders, including several psychiatric disorders. In this regard, it has been hypothesized that epigenetic mechanisms may be the main mediators of such interactions. Of particular interest is the previously described interaction between psychosocial stress and genetic variability of the serotonin transporter gene (SLC6A4) in its polymorphic region 5-HTTLPR. Here we review the literature concerning SLC6A4 methylation in association with environmental, clinical or genetic variables. While SLC6A4 hypermethylation has typically been described to be independently associated with both early life stress and depressive disorders, only a few papers address whether methylation could mediate the interaction between stress and 5-HTTLPR in predicting psychopathological risk. Nevertheless, research preliminarily indicates a methylation-driven increased vulnerability of carriers of the short allele of 5-HTTLPR to psychiatric disorders when exposed to early stress or soon after exposure to stress.

Physiologically-based pharmacokinetic models: approaches for enabling personalized medicine

Personalized medicine strives to deliver the 'right drug at the right dose' by considering inter-person variability, one of the causes for therapeutic failure in specialized populations of patients. Physiologically-based pharmacokinetic (PBPK) modeling is a key tool in the advancement of personalized medicine to evaluate complex clinical scenarios, making use of physiological information as well as physicochemical data to simulate various physiological states to predict the distribution of pharmacokinetic responses. The increased dependency on PBPK models to address regulatory questions is aligned with the ability of PBPK models to minimize ethical and technical difficulties associated with pharmacokinetic and toxicology experiments for special patient populations. Subpopulation modeling can be achieved through an iterative and integrative approach using an adopt, adapt, develop, assess, amend, and deliver methodology. PBPK modeling has two valuable applications in personalized medicine: (1) determining the importance of certain subpopulations within a distribution of pharmacokinetic responses for a given drug formulation and (2) establishing the formulation design space needed to attain a targeted drug plasma concentration profile. This review article focuses on model development for physiological differences associated with sex (male vs. female), age (pediatric vs. young adults vs. elderly), disease state (healthy vs. unhealthy), and temporal variation (influence of biological rhythms), connecting them to drug product formulation development within the quality by design framework. Although PBPK modeling has come a long way, there is still a lengthy road before it can be fully accepted by pharmacologists, clinicians, and the broader industry.

Role of Acid Sphingomyelinase in the Regulation of Social Behavior and Memory

Major depressive disorder is often associated with deficits in social and cognitive functioning. Mice transgenic for acid sphingomyelinase (t-ASM) were previously shown to have a depressive-like phenotype, which could be normalized by antidepressant treatment. Here, we investigated whether t-ASM mice show deficits in social behavior and memory performance, and whether these possible deficits might be normalized by amitriptyline treatment. Our results revealed that ASM overexpression altered the behavior of mice in a sex-dependent manner. As such, t-ASM female, but not male, mice showed an impaired social preference and a depressive- and anxiogenic-like phenotype, which could be normalized by amitriptyline treatment. Both male and female t-ASM mice showed unaltered preference for social novelty, novel object recognition, and social and object discrimination abilities. Amitriptyline treatment impaired novel object recognition and object discrimination abilities in female, but not in male, wild-type mice, while female t-ASM mice showed unaltered novel object recognition and object discrimination abilities. This study suggests that female t-ASM mice represent a model of depression with comorbid anxiety and social deficits, without memory impairments. It further suggests that ASM overexpression has a protective role against the detrimental effects of amitriptyline on female, but not on male, non-social (object) memory.

Navigating the human gastrointestinal tract for oral drug delivery: Uncharted waters and new frontiers

Many concepts of oral drug delivery are based on our comprehension of human gastrointestinal physiology. Unfortunately, we tend to oversimplify the complex interplay between the various physiological factors in the human gut and, in particular, the dynamics of these transit conditions to which oral dosage forms are exposed. Recent advances in spatial and temporal resolution of medical instrumentation as well as improved access to these technologies have facilitated clinical trials to characterize the dynamic processes within the human gastrointestinal tract. These studies have shown that highly relevant parameters such as fluid volumes, dosage form movement, and pH values in the lumen of the upper GI tract are very dynamic. As a result of these new insights into the human gastrointestinal environment, some common concepts and ideas of oral drug delivery are no longer valid and have to be reviewed in order to ensure efficacy and safety of oral drug therapy.

Roads Less Traveled: Sexual Dimorphism and Mast Cell Contributions to Migraine Pathology

Migraine is a common, little understood, and debilitating disease. It is much more prominent in women than in men (~2/3 are women) but the reasons for female preponderance are not clear. Migraineurs frequently experience severe comorbidities, such as allergies, depression, irritable bowel syndrome, and others; many of the comorbidities are more common in females. Current treatments for migraine are not gender specific, and rarely are migraine and its comorbidities considered and treated by the same specialist. Thus, migraine treatments represent a huge unmet medical need, which will only be addressed with greater understanding of its underlying pathophysiology. We discuss the current knowledge about sex differences in migraine and its comorbidities, and focus on the potential role of mast cells (MCs) in both. Sex-based differences in pain recognition and drug responses, fluid balance, and the blood–brain barrier are recognized but their impact on migraine is not well studied. Furthermore, MCs are well recognized for their prominent role in allergies but much less is known about their contributions to pain pathways in general and migraine specifically. MC-neuron bidirectional communication uniquely positions these cells as potential initiators and/or perpetuators of pain. MCs can secrete nociceptor sensitizing and activating agents, such as serotonin, prostaglandins, histamine, and proteolytic enzymes that can also activate the pain-mediating transient receptor potential vanilloid channels. MCs express receptors for both estrogen and progesterone that induce degranulation upon binding. Furthermore, environmental estrogens, such as Bisphenol A, activate MCs in preclinical models but their impact on pain pathways or migraine is understudied. We hope that this discussion will encourage scientists and physicians alike to bridge the knowledge gaps linking sex, MCs, and migraine to develop better, more comprehensive treatments for migraine patients.

Gender differences in the treatment of first-episode schizophrenia: Results from the European First Episode Schizophrenia Trial

Gender differences in the response to antipsychotic treatment have been detected in the past, but not studied in great detail. The results of the European First-Episode Schizophrenia Trial (EUFEST) were analyzed with a focus on gender differences in the response to randomized treatment of first-episode schizophrenia. A total of 498 patients (298 men and 200 women) were randomly assigned by a web-based online system to open-label treatment with haloperidol, amisulpride, olanzapine, quetiapine, and ziprasidone. Treatment response was evaluated using the positive and negative syndrome scale (PANSS). Data were collected at baseline and then prospectively for one year. Baseline characteristics (age and proportion of patients assigned to individual antipsychotics) were the same between the male and female patients with the exception of ziprasidone: significantly fewer men, proportionately, were prescribed ziprasidone. There was no significant difference between genders between the initial total PANSS and subscale scores. A significant interaction between time and gender was found, with more robust PPANSS and TPANSS score improvement in women during the course of treatment. Of all of the antipsychotics used, only olanzapine led to significantly greater improvement in the total PANSS score in women during the follow-up period. Gender differences should be given more attention in research and clinical practice. Their causes require clarification, and future strategies for dealing with them may be considered in early intervention programs and guidelines.

Sex differences in anxiety disorders: Interactions between fear, stress, and gonadal hormones

This article is part of a Special Issue "SBN 2014". Women are more vulnerable to stress- and fear-based disorders, such as anxiety and post-traumatic stress disorder. Despite the growing literature on this topic, the neural basis of these sex differences remains unclear, and the findings appear inconsistent. The neurobiological mechanisms of fear and stress in learning and memory processes have been extensively studied, and the crosstalk between these systems is beginning to explain the disproportionate incidence and differences in symptomatology and remission within these psychopathologies. In this review, we discuss the intersect between stress and fear mechanisms and their modulation by gonadal hormones and discuss the relevance of this information to sex differences in anxiety and fear-based disorders. Understanding these converging influences is imperative to the development of more effective, individualized treatments that take sex and hormones into account.