Prevalence of autoimmune diseases in functional neurological disorder: influence of psychiatric comorbidities and biological sex.

BACKGROUND: Functional neurological disorder (FND) is a common and disabling neuropsychiatric condition, which disproportionally affects women compared with men. While the etiopathogenesis of this disorder remains elusive, immune dysregulation is emerging as one potential mechanism. To begin to understand the role of immune dysfunctions in FND, we assessed the prevalence of several common autoimmune diseases (ADs) in a large cohort of patients with FND and examined the influence of psychiatric comorbidities and biological sex. METHODS: Using a large biorepository database (Mass General Brigham Biobank), we obtained demographic and clinical data of a cohort of 643 patients diagnosed with FND between January 2015 and December 2021. The proportion of ADs was calculated overall, by sex and by the presence of psychiatric comorbidities. RESULTS: The overall prevalence of ADs in our sample was 41.9%, with connective tissue and autoimmune endocrine diseases being the most commonly observed ADs. Among patients with FND and ADs, 27.7% had ≥2 ADs and 8% met criteria for multiple autoimmune syndrome. Rates of ADs were significantly higher in subjects with comorbid major depressive disorder and post-traumatic stress disorder (p= 0.02). Women represented the largest proportion of patients with concurrent ADs, both in the overall sample and in the subgroups of interest (p's < 0.05). CONCLUSIONS: This study is unique in providing evidence of an association between FND and ADs. Future studies are needed to investigate the mechanisms underlying this association and to understand whether FND is characterised by distinct dysregulations in immune response.

Sex-Related Differences in Patient Characteristics, Risk Factors, and Symptomatology in Older Adults with Pulmonary Embolism: Findings from the SERIOUS-PE Study.

Sex-specific factors are implicated in pulmonary embolism (PE) presentation in young patients, as indicated by increased risk in pregnancy. Whether sex differences exist in PE presentation, comorbidities, and symptomatology in older adults, the age group in which most PEs occur, remains unknown. We identified older adults (aged ≥65 years) with PE in a large international PE registry replete with information about relevant clinical characteristics (RIETE registry, 2001-2021). To provide national data from the United States, we assessed sex differences in clinical characteristics and risk factors of Medicare beneficiaries with PE (2001-2019). The majority of older adults with PE in RIETE (19,294/33,462, 57.7%) and in the Medicare database (551,492/948,823, 58.7%) were women. Compared with men, women with PE less frequently had atherosclerotic diseases, lung disease, cancer, or unprovoked PE, but more frequently had varicose veins, depression, prolonged immobility, or history of hormonal therapy (p < 0.001 for all). Women less often presented with chest pain (37.3 vs. 40.6%) or hemoptysis (2.4 vs. 5.6%) but more often with dyspnea (84.6 vs. 80.9%) (p < 0.001 for all). Measures of clot burden, PE risk stratification, and use of imaging modalities were comparable between women and men. PE is more common in elderly women than in men. Cancer and cardiovascular disease are more common in men, whereas transient provoking factors including trauma, immobility, or hormone therapy are more common in elderly women with PE. Whether such differences correlate with disparities in treatment or differences in short- or long-term clinical outcomes warrants further investigation.

Protective effects of elevated anandamide on stress and fear-related behaviors: translational evidence from humans and mice.

Post-traumatic stress disorder (PTSD) is a common, debilitating condition with limited treatment options. Extinction of fear memories through prolonged exposure therapy, the primary evidence-based behavioral treatment for PTSD, has only partial efficacy. In mice, pharmacological inhibition of fatty acid amide hydrolase (FAAH) produces elevated levels of anandamide (AEA) and promotes fear extinction, suggesting that FAAH inhibitors may aid fear extinction-based treatments. A human FAAH 385C->A substitution encodes an FAAH enzyme with reduced catabolic efficacy. Individuals homozygous for the FAAH 385A allele may therefore offer a genetic model to evaluate the impact of elevations in AEA signaling in humans, helping to inform whether FAAH inhibitors have the potential to facilitate fear extinction therapy for PTSD. To overcome the challenge posed by low frequency of the AA genotype (appr. 5%), we prospectively genotyped 423 individuals to examine the balanced groups of CC, AC, and AA individuals (n = 25/group). Consistent with its loss-of-function nature, the A allele was dose dependently associated with elevated basal AEA levels, facilitated fear extinction, and enhanced the extinction recall. Moreover, the A-allele homozygotes were protected against stress-induced decreases in AEA and negative emotional consequences of stress. In a humanized mouse model, AA homozygous mice were similarly protected against stress-induced decreases in AEA, both in the periphery, and also in the amygdala and prefrontal cortex, brain structures critically involved in fear extinction and regulation of stress responses. Collectively, these data suggest that AEA signaling can temper aspects of the stress response and that FAAH inhibition may aid the treatment for stress-related psychiatric disorders, such as PTSD.

Effects of TPH2 gene variation and childhood trauma on the clinical and circuit-level phenotype of functional movement disorders.

BACKGROUND: Functional movement disorders (FMDs), part of the wide spectrum of functional neurological disorders (conversion disorders), are common and often associated with a poor prognosis. Nevertheless, little is known about their neurobiological underpinnings, particularly with regard to the contribution of genetic factors. Because FMD and stress-related disorders share a common core of biobehavioural manifestations, we investigated whether variants in stress-related genes also contributed, directly and interactively with childhood trauma, to the clinical and circuit-level phenotypes of FMD. METHODS: Sixty-nine patients with a 'clinically defined' diagnosis of FMD were genotyped for 18 single-nucleotide polymorphisms (SNPs) from 14 candidate genes. FMD clinical characteristics, psychiatric comorbidity and symptomatology, and childhood trauma exposure were assessed. Resting-state functional connectivity data were obtained in a subgroup of 38 patients with FMD and 38 age-matched and sex-matched healthy controls. Amygdala-frontal connectivity was analysed using a whole-brain seed-based approach. RESULTS: Among the SNPs analysed, a tryptophan hydroxylase 2 (TPH2) gene polymorphism-G703T-significantly predicted clinical and neurocircuitry manifestations of FMD. Relative to GG homozygotes, T carriers were characterised by earlier FMD age of onset and decreased connectivity between the right amygdala and the middle frontal gyrus. Furthermore, the TPH2 genotype showed a significant interaction with childhood trauma in predicting worse symptom severity. CONCLUSIONS: This is, to our knowledge, the first study showing that the TPH2 genotype may modulate FMD both directly and interactively with childhood trauma. Because both this polymorphism and early-life stress alter serotonin levels, our findings support a potential molecular mechanism modulating FMD phenotype.

Neural correlates of cue- and stress-induced craving in gambling disorders: implications for transcranial magnetic stimulation interventions.

Gambling disorder (GD), currently considered a behavioral addiction, shows substantial similarities with substance use disorders (SUDs) in terms of neurobiology and phenomenology. These similarities have been recognized in the DSM-5, although several relevant differences still exist in the diagnostic criteria, in particular, with regard to the role of cue- and stress- induced craving. Craving, recently included as a new criterion for SUDs diagnosis only, is a key construct also in the pathophysiology of GD. Furthermore, brain imaging studies indicate that similar alterations in cortico-limbic-striatal and prefrontal control circuits underlie the emergence of craving states in both disorders. This has important implications for the identification of neurobiologically based anti-craving interventions, which may be used for both GD and SUDs. In this regard, a novel neuromodulation intervention, named repetitive transcranial magnetic stimulation (rTMS), is emerging as a promising treatment for craving in SUDs, and could potentially be effective also in treating gambling urges. Here, we review the clinical neurobiological research on GD, with a specific emphasis on the neural circuits implicated in cue- and stress-craving, taking SUDs as the major comparative example. Furthermore, we describe the studies that have evaluated rTMS as a therapeutic tool for targeting and restoring the neural alterations underlying gambling urge. The manuscript concludes discussing some of the limitations of the current studies, and suggests directions for future rTMS research in GD.

Lack of Target Engagement Following Low-Frequency Deep Transcranial Magnetic Stimulation of the Anterior Insula.

OBJECTIVE: To evaluate the safety and efficacy of low-frequency, inhibitory, deep rTMS with a novel H-coil specifically designed to stimulate the insula. METHODS: In a randomized, crossover order, 16 healthy volunteers underwent two sessions (sham; active) of 1 Hz repetitive TMS at an intensity of 120% of individual motor threshold, over the right anterior insular cortex localized using a neuronavigation system. Before, immediately after, and one hour after rTMS, subjects performed two tasks that have previously been shown in fMRI experiments to activate insular cortex: A blink suppression task and a forced-choice risk-taking task. RESULTS: No drop-outs or adverse events occurred. Active deep rTMS did not result in decreased urge to blink compared to sham. Similarly, no significant time × condition interaction on risk-taking behavior was found. CONCLUSIONS: Low-frequency deep rTMS using a novel H8 coil was shown to be safe but did not affect any of the behavioral markers, also used to investigate modulation of insula activity. Our findings highlight the challenges of modulating the activity of deep brain regions with TMS. Further studies are necessary to identify effective stimulation parameters for deep targets, and to characterize the effects of deep TMS on overlying cortical regions.

Neuromodulation interventions for addictive disorders: challenges, promise, and roadmap for future research.

Addictive disorders are a major public health concern, associated with high relapse rates, significant disability and substantial mortality. Unfortunately, current interventions are only modestly effective. Preclinical studies as well as human neuroimaging studies have provided strong evidence that the observable behaviours that characterize the addiction phenotype, such as compulsive drug consumption, impaired self-control, and behavioural inflexibility, reflect underlying dysregulation and malfunction in specific neural circuits. These developments have been accompanied by advances in neuromodulation interventions, both invasive as deep brain stimulation, and non-invasive such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. These interventions appear particularly promising as they may not only allow us to probe affected brain circuits in addictive disorders, but also seem to have unique therapeutic applications to directly target and remodel impaired circuits. However, the available literature is still relatively small and sparse, and the long-term safety and efficacy of these interventions need to be confirmed. Here we review the literature on the use of neuromodulation in addictive disorders to highlight progress limitations with the aim to suggest future directions for this field.

Severity of alcohol dependence is associated with the fatty acid amide hydrolase Pro129Thr missense variant.

The endocannabinoid system plays an important role in reward and addiction. One of the two main endocannabinoid neurotransmitters, anandamide, is metabolized by fatty acid amide hydrolase, an enzyme with a functional genetic polymorphism (FAAH Pro129Thr, rs324420). The Thr129 allele has been linked to problem drug and alcohol use, but the association has not been widely replicated and may be stronger for clinical measures of severity rather than categorical diagnosis. In the present study, we sought to determine whether the Thr129 allele was associated with both alcohol dependence (AD) diagnosis and severity in a sample of 1434 European American and African American individuals, 952 of whom were diagnosed with lifetime AD. Participants were genotyped for FAAH rs324420, and ancestry was determined via a genome-wide panel of ancestry informative markers. Subjects participated in Structured Clinical Interviews for psychiatric disorders and 90-day Timeline Followback interviews to assess recent alcohol use. European American participants with current AD had a higher Thr129 allele frequency than non-dependent controls. In European Americans with lifetime AD, there were significantly different distributions of drinking days and binge drinking days between the two genotype groups, with Thr129 carriers reporting a median of 10 fewer abstinent days and 13 more binge drinking days than Pro129/Pro129 homozygotes. In African American participants, there were no significant differences between Thr129 allele frequency in cases and controls and no significant differences in measures of AD severity by genotype. These findings provide evidence that the Pro129Thr missense variant is associated with AD severity in European Americans.

Encoding of Touch Intensity But Not Pleasantness in Human Primary Somatosensory Cortex.

UNLABELLED: Growing interest in affective touch has delineated a neural network that bypasses primary somatosensory cortex (S1). Several recent studies, however, have cast doubt on the segregation of touch discrimination and affect, suggesting that S1 also encodes affective qualities. We used functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS) to examine the role of S1 in processing touch intensity and pleasantness. Twenty-six healthy human adults rated brushing on the hand during fMRI. Intensity ratings significantly predicted activation in S1, whereas pleasantness ratings predicted activation only in the anterior cingulate cortex. Nineteen subjects also received inhibitory rTMS over right hemisphere S1 and the vertex (control). After S1 rTMS, but not after vertex rTMS, sensory discrimination was reduced and subjects with reduced sensory discrimination rated touch as more intense. In contrast, rTMS did not alter ratings of touch pleasantness. Our findings support divergent neural processing of touch intensity and pleasantness, with affective touch encoded outside of S1. SIGNIFICANCE STATEMENT: Growing interest in affective touch has identified a neural network that bypasses primary somatosensory cortex (S1). Several recent studies, however, cast doubt on the separation of touch discrimination and affect. We used functional magnetic resonance imaging and repetitive transcranial magnetic stimulation to demonstrate the representation of touch discrimination and intensity in S1, but the representation of pleasantness in the anterior cingulate cortex, not S1. Our findings support divergent neural processing of touch intensity and pleasantness, with affective touch encoded outside of S1. Our study contributes to growing delineation of the affective touch system, a crucial step in understanding its dysregulation in numerous clinical conditions such as autism, eating disorders, depression, and chronic pain.

FAAH Gene Variation Moderates Stress Response and Symptom Severity in Patients with Posttraumatic Stress Disorder and Comorbid Alcohol Dependence.

BACKGROUND: A common single nucleotide polymorphism (C385A) in the human fatty acid amide hydrolase (FAAH) gene has been associated with decreased distress responses in healthy volunteers, but its role in psychiatric disorders remains unknown. Here, we obtained genotypes and carried out a secondary analysis of subjects from a trial of comorbid posttraumatic stress disorder (PTSD) and alcohol dependence (AD). We evaluated the effects of C385A variation on behavioral and biochemical biomarkers of distress responses. METHODS: Forty-nine patients with PTSD and AD were admitted for 4 weeks to an experimental medicine unit at the National Institutes of Health Clinical Center. Following detoxification, stress reactivity and peripheral endocannabinoid (eCB) levels were assessed in response to a challenge session using personalized auditory guided imagery. Over the course of the study, subjects were also evaluated for changes in PTSD symptom severity. RESULTS: FAAH C385A allele carriers showed a marked increase in serum anandamide levels at baseline and throughout the stress challenge procedure compared with C allele homozygotes, while levels of eCBs primarily metabolized through other enzymatic activity, such as 2-arachidonoylglycerol, did not differ between genotype groups. FAAH C385A carriers also had decreased subjective anxiety responses to the stress challenge. Similar effects of FAAH C385A genotype were found at the level of clinical PTSD symptom severity, in particular in the arousal domain. CONCLUSIONS: This is to our knowledge the first study showing that FAAH C385A variation modulates stress responses in subjects with disorders characterized by increased stress reactivity. These findings point to the eCB pathway as a promising target for future antistress therapeutics.

The role of expectation in the therapeutic outcomes of alcohol and drug addiction treatments.

Throughout history, patient-physician relationships have been acknowledged as an important component of the therapeutic effects of any pharmacological treatment. Here, we discuss the role of physicians' expectations in influencing the therapeutic outcomes of alcohol and drug addiction pharmacological treatments. As largely demonstrated, such expectations and attitudes may contribute to produce placebo and nocebo effects that in turn affect the course of the disease and the response to the therapy. This article is aimed at discussing the current insights into expectations, placebo and nocebo mechanisms and their impact on the therapeutic outcomes of alcohol and drug addiction treatments; with the goal of informing physicians and other health care providers about the potentially widespread implications for clinical practice and for a successful treatment regimen.

Effects of naltrexone on neural and subjective response to alcohol in treatment-seeking alcohol-dependent patients.

BACKGROUND: Positively reinforcing properties of alcohol are in part mediated by activation of the ventral striatum (VS). Alcohol-induced release of endogenous opioids is thought to contribute to this response. Preclinical studies show that the opioid antagonist naltrexone (NTX) can block this cascade, but its ability to do so in treatment-seeking alcoholics has not been examined. Our objective was to study the effects of NTX on alcohol-induced VS activation and on amygdala response to affective stimuli in treatment-seeking alcohol-dependent inpatients. METHODS: Sixty-three treatment-seeking alcoholics were randomized to receive NTX (50 mg) or placebo (PLC) daily. On Day 7, participants underwent an alcohol cue reactivity session, and craving was measured using the Penn Alcohol Craving Scale. On Day 9, participants received a saline infusion followed by an alcohol infusion and also viewed affective stimuli in a magnetic resonance scanner. RESULTS: Irrespective of medication treatment condition, the alcohol infusion did not activate the VS in the alcohol-dependent patients. Unexpectedly, VS activation was greater in NTX treated patients than in the PLC group. NTX treated patients also reported increased craving in response to alcohol cue exposure, and increased subjective response to alcohol ("high" and "intoxicated") compared to PLC subjects. No significant effects of alcohol infusion on brain response to affective stimuli were in the NTX or PLC groups. CONCLUSIONS: Unlike previous findings in social drinkers, a moderate level of intoxication did not activate the VS in treatment-seeking alcoholics. This is likely to reflect tolerance to the positively reinforcing properties of alcohol in this clinical population. Our findings may help explain the efficacy of NTX to reduce heavy drinking, but not to maintain abstinence.

Functional Movement Disorder Is Associated with Abnormal Interoceptive Brain Activity: A Task-based Functional MRI Study.

Background: Aberrant interoceptive processing has been hypothesized to contribute to the pathophysiology of functional neurological disorder, although findings have been inconsistent. Here, we utilized functional magnetic resonance imaging (fMRI) to examine neural correlates of interoceptive attention - the conscious focus and awareness of bodily sensations - in functional movement disorder (FMD). Methods: We used voxelwise analyses to compare blood oxygenation level-dependent responses between 13 adults with hyperkinetic FMD and 13 healthy controls (HCs) during a task requiring attention to different bodily sensations and to an exteroceptive stimulus. Additionally, we examined between-group differences in self-reported measures of interoception and evaluated their relationship with neural activity. Results: Interoceptive conditions (heartbeat, stomach and 'body', indicating sensations from the body part or limb affected in FMD participants) activated a network involving the precuneus, the posterior cingulate cortex (PCC) and caudate nucleus (CN) bilaterally, and the right anterior insula (aINS) (p <0.05, corrected). Group differences in brain activity were mainly driven by processing of disease-related interoceptive signals, which in the FMD group was associated with a broader neural activation than monitoring gastric interoception, while no group differences were detected during cardiac interoception. Differences based on interoceptive focus (body vs heartbeat and stomach) between FMD subjects and HCs were found in PCC, CN, angular gyrus, thalamus, and in the mid-insula (p <0.05, corrected). Conclusions: This is, to our knowledge, the first study showing that FMD is associated with abnormal interoceptive processing in regions involved in monitoring body state, attentional focus, and homeostatic inference.

Methylome changes associated with functional movement/conversion disorder: Influence of biological sex and childhood abuse exposure.

Epigenetic changes, such as DNA methylation (DNAm), may represent an important mechanism implicated in the etiopathogenesis of functional movement/conversion disorder (FMD). Here, we aimed to identify methylomic variations in a case-control cohort of FMD and to uncover specific epigenetic signatures associated with female sex and childhood abuse, two key risk factors for FMD and other functional neurological disorders. Genome-wide DNAm analysis was performed from peripheral blood in 57 patients with FMD and 47 healthy controls with and without childhood abuse. Using principal component analysis, we examined the association of principal components with FMD status in abused and non-abused individuals, in the entire study sample and in female subjects only. Next, we used enrichment pathway analysis to investigate the biological significance of DNAm changes and explored differences in methylation levels of genes annotated to the top enriched biological pathways shared across comparisons. We found that FMD was associated with DNAm variation across the genome and identified a common epigenetic 'signature' enriched for biological pathways implicated in chronic stress and chronic pain. However, methylation levels of genes included in the top two shared pathways hardly overlapped, suggesting that transcriptional profiles may differ as a function of childhood abuse exposure and sex among subjects with FMD. This study is unique in providing genome-wide evidence of DNAm changes in FMD and in indicating a potential mechanism linking childhood abuse exposure and female sex to differences in FMD pathophysiology. Future studies are needed to replicate our findings in independent cohorts.

Impact of cannabidiol on reward- and stress-related neurocognitive processes among individuals with opioid use disorder: A pilot, double-blind, placebo-controlled, randomized cross-over trial.

Introduction: Opioid use disorder (OUD) continues to be a significant public health concern. Medications for OUD (MOUD) such as buprenorphine reduce overdose mortality, but relapses occur often, leading to adverse outcomes. Preliminary data suggest that cannabidiol (CBD) may be a potential adjunctive treatment to MOUD by attenuating cue-reactivity. This pilot study sought to evaluate the impact of a single dose of CBD on reward- and stress-related neurocognitive processes implicated in relapse among those with OUD. Methods: The study was a pilot, double-blind, placebo-controlled, randomized cross-over trial aimed at assessing the effects of a single dose of CBD (Epidiolex®) 600 mg or matching placebo administered to participants with OUD receiving either buprenorphine or methadone. Vital signs, mood states, pain, opioid withdrawal, cue-induced craving, attentional bias, decision-making, delayed discount, distress tolerance, and stress-reactivity were examined at each testing session on two separate testing days at least 1 week apart. Results: Ten participants completed all study procedures. Receipt of CBD was associated with a significant decrease in cue-induced craving (0.2 vs. 1.3, p = 0.040), as well as reduced attentional bias toward drug-related cues as measured by the visual probe task (-80.4 vs. 100.3, p = 0.041). No differences were found among all the other outcomes examined. Discussion: CBD may have promise as an adjunct to MOUD treatment by attenuating the brain response to drug-related cues, which, in turn, may reduce the risk of relapse and overdoses. Further research is warranted to evaluate the potential for CBD as an adjunctive therapy for individuals in treatment for OUD. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04982029.

Enrollment of female participants in United States drug and device phase 1-3 clinical trials between 2016 and 2019.

BACKGROUND: Historically, females have been underrepresented in clinical trials evaluating the safety and efficacy of investigational drugs and devices. We assessed participation by sex in recent clinical trials. METHODS: We extracted data over a 4-year period (2016-2019) from ClinicalTrials.gov on US-based, pharmaceutical industry or government-funded Phase 1-3 clinical trials of drugs and devices. We included trials with adult cardiovascular, psychiatric, and cancer endpoints whose protocol planned to enroll both sexes. Average proportions of females enrolled per trial were described overall and by disease area. RESULTS: Across 1433 trials including 302,664 participants in our analysis, on average, 41.2% were female. Females were underrepresented compared with their proportion of the disease population in cardiovascular disease trials (41.9% female participants vs. 49% female population with cardiovascular disease). In psychiatry, where females comprise 60% of patients, the mean participation of females in clinical trials was 42.0%. Similarly, for cancer trials, where 51% of patients are female, only 41.0% of cancer clinical trial participants were female. For each therapeutic area analyzed, the participation of females in clinical trials fell short of the benchmark derived from national prevalence data. CONCLUSIONS: While the participation of females in clinical trials has improved compared to previous reports, sex-based gaps still persist between trial populations and those expected to use these drugs/devices based on distributions of diseases in the population. Given potential sex-based differences in treatment responses and toxicities, adequate inclusion of females in clinical trials remains critical.

Analysis of female enrollment in clinical trials for alcohol and substance use disorders: Is it time for sex-informed pharmacotherapy?

BACKGROUND: Women represent an increasing number of individuals with alcohol and substance use disorders (ASUDs), and sex-differences might affect results of interventional clinical trials (CTs). We aim at assessing the proportion of women and the reporting of sex-stratified and female-specific data in CTs for ASUDs. METHODS: We extracted data from ClinicalTrials.gov on Phase 1-3 CTs of investigational drugs for ASUDs conducted from 2000 to 2021 and identified articles related to these trials. We determined the average proportions of women enrolled per trial overall, over time, and by disease area and trial phase. Next, we calculated the proportion of articles reporting sex-stratified and female-specific data. RESULTS: In the 234 CTs identified, the overall proportion of women was 33.4% [95% CI: 32.7%-33.9%]), with an increasing temporal trend. Women's participation was higher in CTs of investigational drugs for tobacco (43.5% [95% CI: 42.4% -44.5%]) and alcohol use disorder (35.9% [95% CI: 34.54%-37.21%]), and closely mirrored their representation in the disease populations (46% and 37%). Conversely, women were underrepresented in clinical trials of drugs for cocaine and stimulant use disorders (25.8% [95% CI: 24.6%-27.1%]) and opioid use disorders (25.9% [95% CI:24.2%-27.7%]). Nine publications reported sex-stratified data in the method and/or result section, whereas none documented female-specific data. CONCLUSIONS: Enrollment of women in ASUDs CTs has increased over time but remains low in several disease areas. This, together with the low rates of reporting of sex-stratified data, calls for an adequate inclusion of sex in the design and analysis of CTs for ASUDs.

A dimensional approach to functional movement disorders: Heresy or opportunity.

Functional movement disorders (FMD) are a common and disabling neuropsychiatric condition, part of the spectrum of functional neurological/conversion disorder. FMD represent one of the most enigmatic disorders in the history of medicine. However, in the twenty years after the first report of distinctive abnormal brain activity associated with functional motor symptoms, there have been tremendous advances in the pathophysiologic understanding of these disorders. FMD can be characterized as a disorder of aberrant neurocircuitry interacting with environmental and genetic factors. These developments suggest that research on FMD could be better served by an integrative, neuroscience-based approach focused on functional domains and their neurobiological substrates. This approach has been developed in 'Research Domain Criteria' (RDoC) project, which promotes a dimensional approach to psychiatric disorders. Here, we use the RDoC conceptualization to review recent neuroscience research on FMD, focusing on the domains most relevant to these disorders. We discuss how the adoption of a similar integrative framework may facilitate the identification of the mechanisms underlying FMD and could also have potential clinical applicability.