Sexual Reassignment Fails to Prevent Kennedy's Disease

Neurological care for LGBT+ people

Sexual and gender minority (LGBT+) people face unique health disparities that must be considered by health-care providers to ensure equitable and inclusive care. Although traditionally LGBT+ health has not been integrated into neurology training, sexual orientation and gender identity have direct relevance to neurological health, driven by both systemic and interpersonal factors. In this Review, we summarize the evidence for associations between sexual orientation and gender identity with the prevalence and outcomes of various neurological conditions, including neurodegenerative diseases, epilepsy, stroke and neurodevelopmental disorders, among others. We describe important clinical considerations pertaining to LGBT+ people and recommend language and practices to promote inclusive care, as well as highlight gaps in need of further research and possible strategies to minimize these, including systematic collection of sexual orientation and gender identity and use of inclusive language.

Ligand-free mitochondria-localized mutant AR-induced cytotoxicity in spinal bulbar muscular atrophy

Spinal bulbar muscular atrophy (SBMA), the first identified CAG-repeat expansion disorder, is an X-linked neuromuscular disorder involving CAG-repeat-expansion mutations in the androgen receptor (AR) gene. We utilized CRISPR-Cas9 gene editing to engineer novel isogenic human induced pluripotent stem cell (hiPSC) models, consisting of isogenic AR knockout, control and disease lines expressing mutant AR with distinct repeat lengths, as well as control and disease lines expressing FLAG-tagged wild-type and mutant AR, respectively. Adapting a small-molecule cocktail-directed approach, we differentiate the isogenic hiPSC models into motor neuron-like cells with a highly enriched population to uncover cell-type-specific mechanisms underlying SBMA and to distinguish gain- from loss-of-function properties of mutant AR in disease motor neurons. We demonstrate that ligand-free mutant AR causes drastic mitochondrial dysfunction in neurites of differentiated disease motor neurons due to gain-of-function mechanisms and such cytotoxicity can be amplified upon ligand (androgens) treatment. We further show that aberrant interaction between ligand-free, mitochondria-localized mutant AR and F-ATP synthase is associated with compromised mitochondrial respiration and multiple other mitochondrial impairments. These findings counter the established notion that androgens are requisite for mutant AR-induced cytotoxicity in SBMA, reveal a compelling mechanistic link between ligand-free mutant AR, F-ATP synthase and mitochondrial dysfunction, and provide innovative insights into motor neuron-specific therapeutic interventions for SBMA.

Sexual and Gender Minority Health in Neurology: A Scoping Review

Importance

Little is known about the neurologic health needs of sexual and gender minority (SGM) individuals, and existing research indicates health care disparities for this group.

Objective

To describe the current state of science in SGM neurology and highlight areas of knowledge and gaps to guide future research.

Evidence Review

All articles published before April 12, 2020, in PubMed, Embase, Web of Science, PsycInfo, CINAHL, and BIOSIS Previews were searched using a search string encompassing SGM descriptors and neurologic disorders. A total of 8359 items were found and entered into EndNote, and 2921 duplicates were removed. A blind title and abstract review was performed followed by full-text review in duplicate, with conflicts settled through consensus, to identify 348 articles eligible for data abstraction. Articles presenting primary data about an identified adult SGM population addressing a clinical neurology topic were included. Descriptive statistics were used for abstracted variables.

Findings

Of 348 studies, 205 (58.9%) were case reports or series, 252 (72.4%) included sexual minority cisgender men, and 247 (70.9%) focused on HIV. An association was found between autism spectrum disorder and gender dysphoria in 9 of 16 studies (56.3%), and a higher risk of ischemic stroke in transgender women was shown in other studies. Literature in neuroinfectious disease, the most common topic, largely focused on HIV (173 of 200 studies [86.5%]). Findings in other neurologic topics were limited by lack of data.

Conclusions and Relevance

In this rigorous compendium of SGM neurology literature, several deficiencies were found: most studies focused on a limited breadth of neurologic pathology, included only a portion of the overall SGM community, and did not assess other aspects of sociodemographic diversity that may contribute to disparities in health care access and outcomes among SGM individuals. Expanding neurologic research to include broader representation of SGM individuals and incorporating sociodemographic factors, like race/ethnicity and socioeconomic status, are essential steps toward providing equitable neurologic care for this community.

The Role of Sex and Sex Hormones in Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a wide class of disorders of the central nervous system (CNS) with unknown etiology. Several factors were hypothesized to be involved in the pathogenesis of these diseases, including genetic and environmental factors. Many of these diseases show a sex prevalence and sex steroids were shown to have a role in the progression of specific forms of neurodegeneration. Estrogens were reported to be neuroprotective through their action on cognate nuclear and membrane receptors, while adverse effects of male hormones have been described on neuronal cells, although some data also suggest neuroprotective activities. The response of the CNS to sex steroids is a complex and integrated process that depends on (i) the type and amount of the cognate steroid receptor and (ii) the target cell type-either neurons, glia, or microglia. Moreover, the levels of sex steroids in the CNS fluctuate due to gonadal activities and to local metabolism and synthesis. Importantly, biochemical processes involved in the pathogenesis of NDs are increasingly being recognized as different between the two sexes and as influenced by sex steroids. The aim of this review is to present current state-of-the-art understanding on the potential role of sex steroids and their receptors on the onset and progression of major neurodegenerative disorders, namely, Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, and the peculiar motoneuron disease spinal and bulbar muscular atrophy, in which hormonal therapy is potentially useful as disease modifier.

Molecular Mechanisms and Therapeutics for SBMA/Kennedy's Disease

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR). Despite the fact that the monogenic cause of SBMA has been known for nearly 3 decades, there is no effective treatment for this disease, underscoring the complexity of the pathogenic mechanisms that lead to a loss of motor neurons and muscle in SBMA patients. In the current review, we provide an overview of the system-wide clinical features of SBMA, summarize the structure and function of the AR, discuss both gain-of-function and loss-of-function mechanisms of toxicity caused by polyQ-expanded AR, and describe the cell and animal models utilized in the study of SBMA. Additionally, we summarize previously conducted clinical trials which, despite being based on positive results from preclinical studies, proved to be largely ineffective in the treatment of SBMA; nonetheless, these studies provide important insights as researchers develop the next generation of therapies.

American Academy of Neurology members' preparedness to treat sexual and gender minorities

Objective

To measure the attitudes and knowledge of American Academy of Neurology (AAN) member neurologists in caring for sexual and gender minority (SGM) patients (e.g., those who identify in the lesbian, gay, bisexual, transgender, queer, or questioning [LGBTQ+] spectrum) to inform future educational offerings.

Methods

A questionnaire was created in an iterative process by the LGBTQ+ Survey Task Force, consisting of 21 questions examining self-reported knowledge, attitudes, and clinical preparedness in caring for SGM patients. Participants responded to each statement with a 5-point Likert scale (“strongly disagree” to “strongly agree”). The survey was distributed via electronic and conventional mail to a random, representative sample of 1,000 AAN members.

Results

The response rate was 13.5% (n = 135). Most respondents (60%–66%) were aware of local and national barriers that inhibit SGM individuals from using health care services; the majority (73%–91%) felt comfortable assessing SGM patients. Over half believed sexual orientation (SO) and gender identity (GI) to be social determinants of health (61% and 57%, respectively). Yet a third would not tailor neurologic care based on a patient's SGM identity, and 43% believed that SO/GI has no bearing on the management of neurologic illness.

Conclusions

Most neurologists surveyed were aware of overarching barriers to care experienced by SGM individuals; however, a minority of respondents recognized the intersection of SGM identity with neurologic health. Our results highlight awareness gaps that could be addressed via targeted educational opportunities, ensuring that neurologists provide high-quality neurologic care to patients of all sexual orientations and gender identities.

Pre-clinical symptoms of SBMA may not be androgen-dependent: implications from two SBMA mouse models

A distinguishing aspect of spinal and bulbar muscular atrophy (SBMA) is its androgen-dependence, possibly explaining why only males are clinically affected. This disease, which impairs neuromuscular function, is linked to a polyglutamine expansion mutation in the androgen receptor (AR). In mouse models of SBMA, motor dysfunction is associated with pronounced defects in neuromuscular transmission, including defects in evoked transmitter release (quantal content, QC) and fiber membrane excitability (based on the resting membrane potential, RMP). However, whether such defects are androgen-dependent is unknown. Thus, we recorded synaptic potentials intracellularly from adult muscle fibers of transgenic (Tg) AR97Q male mice castrated pre-symptomatically. Although castration largely protects both QC and the RMP of fibers, correlating with the protective effect of castration on motor function, significant deficits in QC and RMP remained. Surprisingly, comparable defects in QC and RMP were also observed in pre-symptomatic AR97Q males, indicating that such defects emerge early and are pre-clinical. Exposing asymptomatic Tg females to androgens also induces both motor dysfunction and comparable defects in QC and RMP. Notably, asymptomatic Tg females also showed significant deficits in QC and RMP, albeit less severe, supporting their pre-clinical nature, but also raising questions about the androgen-dependence of pre-clinical symptoms. In summary, current evidence indicates that disease progression depends on androgens, but early pathogenic events may be triggered by the mutant AR allele independent of androgens. Such early, androgen-independent disease mechanisms may also be relevant to females carrying the SBMA allele.