Return of genetic research results in 21,532 individuals with autism.

PURPOSE: The aim of this study is to identify likely pathogenic (LP) and pathogenic (P) genetic results for autism that can be returned to participants in SPARK (SPARKforAutism.org): a large recontactable cohort of people with autism in the United States. We also describe the process to return these clinically confirmed genetic findings. METHODS: We present results from microarray genotyping and exome sequencing (ES) of 21,532 individuals with autism and 17,785 of their parents. We returned LP and P (American College of Medical genetics (ACMG) criteria) copy number variants (CNVs), chromosomal aneuploidies, and variants in genes with strong evidence of association with autism and intellectual disability. RESULTS: We identified 1903 'returnable' LP/P variants in 1861 individuals with autism (8.6%). 89.5% of these variants were not known to participants. The diagnostic genetic result was returned to 589 participants (53% of those contacted). Features associated with a higher probability of having a returnable result include cognitive and medically complex features, being female, being White (versus non-White) and being diagnosed more than 20 years ago. We also find results among autistics across the spectrum, as well as in transmitting parents with neuropsychiatric features but no autism diagnosis. CONCLUSION: SPARK offers an opportunity to assess returnable results among autistic people who have not been ascertained clinically. SPARK also provides practical experience returning genetic results for a behavioral condition at a large scale.

Comparison of Yamuna (India) and Mississippi River (United States of America) bacterial communities reveals greater diversity below the Yamunotri Glacier.

The Yamuna River in India and the Mississippi River in the United States hold significant commercial, cultural, and ecological importance. This preliminary survey compares the bacterial communities sampled in surface waters at 11 sites (Yamuna headwaters, Mississippi headwaters, Yamuna River Yamunotri Town, Mississippi River at Winona, Tons River, Yamuna River at Paonta Sahib, Yamuna River Delhi-1, Yamuna River Delhi-2, Yamuna River before Sangam, Sangam, Ganga River before Sangam). Bacterial 16S rDNA analyses demonstrate dominance of Proteobacteria and Bacteroidetes phyla. Actinobacteria were also dominant at sites near Sangam in India and sites in Minnesota. A dominance of Epsilonbacteraeota were found in Delhi, India. Principal component analysis (PCA) using unique operational taxonomic units (OTUs) resulted in the identification of 3 groups that included the Yamuna River locations in Delhi (Delhi locations), Yamuna headwaters and Yamuna River at Yamunotri (Yamuna River locations below the Glacier) and Mississippi, Ganga, Tons, and other Yamuna River locations. Diversity indices were significantly higher at the Yamuna River locations below the Glacier (Simpson D = 0.986 and Shannon H = 5.06) as compared (p value <0.001) to the Delhi locations (D = 0.951 and H = 4.23) and as compared (p value < 0.001) to Mississippi, Ganga, Tons, and other Yamuna River locations (D = 0.943 and H = 3.96). To our knowledge, this is the first survey to compare Mississippi and Yamuna River bacterial communities. We demonstrate higher diversity in the bacterial communities below the Yamunotri glacier in India.

Designing target trials using electronic health records: A case study of second-line disease-modifying anti-rheumatic drugs and cardiovascular disease outcomes in patients with rheumatoid arthritis.

BACKGROUND: Emulation of the "target trial" (TT), a hypothetical pragmatic randomized controlled trial (RCT), using observational data can be used to mitigate issues commonly encountered in comparative effectiveness research (CER) when randomized trials are not logistically, ethically, or financially feasible. However, cardiovascular (CV) health research has been slow to adopt TT emulation. Here, we demonstrate the design and analysis of a TT emulation using electronic health records to study the comparative effectiveness of the addition of a disease-modifying anti-rheumatic drug (DMARD) to a regimen of methotrexate on CV events among rheumatoid arthritis (RA) patients. METHODS: We used data from an electronic medical records-based cohort of RA patients from Northwestern Medicine to emulate the TT. Follow-up began 3 months after initial prescription of MTX (2000-2020) and included all available follow-up through June 30, 2020. Weighted pooled logistic regression was used to estimate differences in CVD risk and survival. Cloning was used to handle immortal time bias and weights to improve baseline and time-varying covariate imbalance. RESULTS: We identified 659 eligible people with RA with average follow-up of 46 months and 31 MACE events. The month 24 adjusted risk difference for MACE comparing initiation vs non-initiation of a DMARD was -1.47% (95% confidence interval [CI]: -4.74, 1.95%), and the marginal hazard ratio (HR) was 0.72 (95% CI: 0.71, 1.23). In analyses subject to immortal time bias, the HR was 0.62 (95% CI: 0.29-1.44). CONCLUSION: In this sample, we did not observe evidence of differences in risk of MACE, a finding that is compatible with previously published meta-analyses of RCTs. Thoughtful application of the TT framework provides opportunities to conduct CER in observational data. Benchmarking results of observational analyses to previously published RCTs can lend credibility to interpretation.

First-passage time for many-particle diffusion in space-time random environments.

The first-passage time for a single diffusing particle has been studied extensively, but the first-passage time of a system of many diffusing particles, as is often the case in physical systems, has received little attention until recently. We consider two models for many-particle diffusion-one treats each particle as independent simple random walkers while the other treats them as coupled to a common space-time random forcing field that biases particles nearby in space and time in similar ways. The first-passage time of a single diffusing particle under both models shows the same statistics and scaling behavior. However, for many-particle diffusions, the first-passage time among all particles (the extreme first-passage time) is very different between the two models, effected in the latter case by the randomness of the common forcing field. We develop an asymptotic (in the number of particles and location where first passage is being probed) theoretical framework to separate the impact of the random environment with that of the sampling trajectories within it. We identify a power law describing the impact of the environment on the variance of the extreme first-passage time. Through numerical simulations, we verify that the predictions from this asymptotic theory hold even for systems with widely varying numbers of particles, all the way down to 100 particles. This shows that measurements of the extreme first-passage time for many-particle diffusions provide an indirect measurement of the underlying environment in which the diffusion is occurring.

Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates.

OBJECTIVES: Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation. METHODS: Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA. RESULTS: Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing. DISCUSSION: There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs. CONCLUSION: Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.

A Comparison of Wound Complications Following Total Hip Arthroplasty Performed Through the Direct Anterior Versus Direct Lateral Approach.

Background: Some studies have suggested the risk of wound complications may be higher using the direct anterior (DA) approach to total hip arthroplasty (THA). This study aimed to compare the risk of early postoperative wound complications between the DA and direct lateral (DL) approaches to THA and to determine patient risk factors that may contribute to this problem. Methods: All patients who underwent primary THA with a single surgeon over a 5-year period were retrospectively reviewed. All patients were treated with either the DA or DL approach. Data collected included patient demographics, surgical approach, and wound status. There was a minimum follow-up of 6 weeks to allow for an adequate assessment of surgical wound healing. Univariate and multivariate analyses were used to compare the 2 approaches. Results: Five hundred seventy-nine patients (77.6%) who underwent DA approach and 167 patients (22.4%) who underwent DL approach were included. Patients who underwent DL approach had a higher body mass index and a higher rate of diabetes than those treated with the DA approach. Forty patients (6.9%) in the DA cohort and 14 (8.4%) in the DL cohort experienced early wound complications, P = .523. After controlling for potential confounding variables, the surgical approach was not an independent risk factor for early postoperative wound complications. Conclusions: While there have been concerns regarding use of the DA approach in patients with higher body mass index and certain medical comorbidities, the results of this study suggest the choice of surgical approach may have minimal effect on the rate of early postoperative wound complications.

PKMYT1 is a Marker of Treatment Response and a Therapeutic Target for CDK4/6 Inhibitor-Resistance in ER+ Breast Cancer.

Endocrine therapies (ET) with CDK4/6 inhibition are the standard treatment for estrogen receptor-α-positive (ER+) breast cancer, however drug resistance is common. In this study, proteogenomic analyses of 22 ER+ breast cancer patient-derived xenografts (PDXs) demonstrated that PKMYT1, a WEE1 homolog, is estradiol (E2) regulated in E2-dependent PDXs and constitutively expressed when growth is E2-independent. In clinical samples, high PKMYT1 mRNA levels associated with resistance to both ET and CDK4/6 inhibition. The PKMYT1 inhibitor lunresertib (RP-6306) with gemcitabine selectively and synergistically reduced the viability of ET and palbociclib-resistant ER+ breast cancer cells without functional p53. In vitro the combination increased DNA damage and apoptosis. In palbociclib-resistant, TP53 mutant PDX organoids and xenografts, RP-6306 with low-dose gemcitabine induced greater tumor volume reduction compared to treatment with either single agent. Our study demonstrates the clinical potential of RP-6306 in combination with gemcitabine for ET and CDK4/6 inhibitor resistant TP53 mutant ER+ breast cancer.

Volumetric Analysis of a Novel Chimeric Gracilis and Profunda Artery Perforator Flap.

BACKGROUND: The presence of a chimeric gracilis and profunda artery perforator (PAP) flap with a common arterial pedicle has been demonstrated on computed tomography angiography in up to 59% of patients and confirmed in a cadaveric model. Already utilized for head and neck reconstruction by Heredero et al, this novel flap could provide more volume than either flap alone which is advantageous, particularly in patients with sizable defects. The purpose of this study was to determine the average tissue volume that can be utilized from this chimeric flap. METHODS: CT Angiogram imaging studies exhibiting chimeric flap anatomy were reviewed over a 7-year period at a single institution utilizing Visage Version 7.1, a radiology picture archiving and communication system. This software was used to trace the flap pedicles and to capture estimated soft tissue volumes of each respective flap. RESULTS: A total of 31 patients, consisting of 52 lower extremity gracilis and PAP chimeric flaps, underwent tissue volume analysis. The average total volume of soft tissue supplied by the gracilis flap was found to be 70.21 cm3 (standard deviation [SD] = 26.99). The average volume of the PAP flap was 31.73 cm3 (SD = 26.12). The average total volume captured by the chimeric gracilis and PAP flap was 101.94 cm3 (SD = 62.40). CONCLUSION: The potential soft tissue volume that can be harvested from a chimeric gracilis and PAP flap is significantly greater than solitary gracilis or PAP flaps. This chimeric flap may serve as a viable and advantageous reconstructive option for patients requiring large volume soft tissue coverage, particularly if other sizable options are not available.

Exercise does not cause post-exertional malaise in Veterans with Gulf War Illness: A randomized, controlled, dose-response, crossover study.

Chronic multisymptom illnesses (CMI) such as Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, Long-COVID, and Gulf War Illness (GWI) are associated with an elevated risk of post-exertional malaise (PEM), an acute exacerbation of symptoms and other related outcomes following exercise. These individuals may benefit from personalized exercise prescriptions which prioritize risk minimization, necessitating a better understanding of dose-response effects of exercise intensity on PEM. METHODS: Veterans with GWI (n = 40) completed a randomized controlled crossover experiment comparing 20 min of seated rest to light-, moderate-, and vigorous-intensity cycling conditions over four separate study visits. Symptoms, pain sensitivity, cognitive performance, inflammatory markers (C-reactive protein and plasma cytokines) were measured before and within 1 h after exercise and seated rest. Physical activity behavior was measured ≥ 7 days following each study visit via actigraphy. Linear mixed effects regression models tested the central hypothesis that higher intensity exercise would elicit greater exacerbation of negative outcomes, as indicated by a significant condition-by-time interaction for symptom, pain sensitivity, cognitive performance, and inflammatory marker models and a significant main effect of condition for physical activity models. RESULTS: Significant condition-by-time interactions were not observed for primary or secondary measures of symptoms, pain sensitivity, cognitive performance, and a majority of inflammatory markers. Similarly, a significant effect of condition was not observed for primary or secondary measures of physical activity. CONCLUSIONS: Undesirable effects such as symptom exacerbation were observed for some participants, but the group-level risk of PEM following light-, moderate-, or vigorous-intensity exercise was no greater than seated rest. These findings challenge several prior views about PEM and lend support to a broader body of literature showing that the benefits of exercise outweigh the risks.

Discovery of Potent, Selective, and Orally Available IRE1α Inhibitors Demonstrating Comparable PD Modulation to IRE1 Knockdown in a Multiple Myeloma Model.

The lack of selective and safe in vivo IRE1α tool molecules has limited the evaluation of IRE1α as a viable target to treat multiple myeloma. Focus on improving the physicochemical properties of a literature compound by decreasing lipophilicity, molecular weight, and basicity allowed the discovery of a novel series with a favorable in vitro safety profile and good oral exposure. These efforts culminated in the identification of a potent and selective in vivo tool compound, G-5758, that was well tolerated following multiday oral administration of doses up to 500 mg/kg. G-5758 demonstrated comparable pharmacodynamic effects to induced IRE1 knockdown as measured by XBP1s levels in a multiple myeloma model (KMS-11).

Broadband near-infrared emission in silicon waveguides.

Silicon photonic integrated circuit foundries enable wafer-level fabrication of entire electro-optic systems-on-a-chip for applications ranging from datacommunication to lidar to chemical sensing. However, silicon's indirect bandgap has so far prevented its use as an on-chip optical source for these systems. Here, we describe a fullyintegrated broadband silicon waveguide light source fabricated in a state-of-the-art 300-mm foundry. A reverse-biased p-i-n diode in a silicon waveguide emits broadband near-infrared optical radiation directly into the waveguide mode, resulting in nanowatts of guided optical power from a few milliamps of electrical current. We develop a one-dimensional Planck radiation model for intraband emission from hot carriers to theoretically describe the emission. The brightness of this radiation is demonstrated by using it for broadband characterization of photonic components including Mach-Zehnder interferometers and lattice filters, and for waveguide infrared absorption spectroscopy of liquid-phase analytes. This broadband silicon-based source can be directly integrated with waveguides and photodetectors with no change to existing foundry processes and is expected to find immediate application in optical systems-on-a-chip for metrology, spectroscopy, and sensing.

Single episode of moderate to severe traumatic brain injury leads to chronic neurological deficits and Alzheimer's-like pathological dementia.

Traumatic brain injury (TBI) is one of the foremost causes of disability and mortality globally. While the scientific and medical emphasis is to save lives and avoid disability during acute period of injury, a severe health problem can manifest years after injury. For instance, TBI increases the risk of cognitive impairment in the elderly. Remote TBI history was reported to be a cause of the accelerated clinical trajectory of Alzheimer's disease-related dementia (ADRD) resulting in earlier onset of cognitive impairment and increased AD-associated pathological markers like greater amyloid deposition and cortical thinning. It is not well understood whether a single TBI event may increase the risk of dementia. Moreover, the cellular signaling pathways remain elusive for the chronic effects of TBI on cognition. We have hypothesized that a single TBI induces sustained neuroinflammation and disrupts cellular communication in a way that results later in ADRD pathology. To test this, we induced TBI in young adult CD1 mice and assessed the behavioral outcomes after 11 months followed by pathological, histological, transcriptomic, and MRI assessment. On MRI scans, these mice showed significant loss of tissue, reduced CBF, and higher white matter injury compared to sham mice. We found these brains showed progressive atrophy, markers of ADRD, sustained astrogliosis, loss of neuronal plasticity, and growth factors even after 1-year post-TBI. Because of progressive neurodegeneration, these mice had motor deficits, showed cognitive impairments, and wandered randomly in open field. We, therefore, conclude that progressive pathology after adulthood TBI leads to neurodegenerative conditions such as ADRD and impairs neuronal functions.

Cardiovascular disease and cancer: shared risk factors and mechanisms.

Cardiovascular disease (CVD) and cancer are among the leading causes of morbidity and mortality globally, and these conditions are increasingly recognized to be fundamentally interconnected. In this Review, we present the current epidemiological data for each of the modifiable risk factors shared by the two diseases, including hypertension, hyperlipidaemia, diabetes mellitus, obesity, smoking, diet, physical activity and the social determinants of health. We then review the epidemiological data demonstrating the increased risk of CVD in patients with cancer, as well as the increased risk of cancer in patients with CVD. We also discuss the shared mechanisms implicated in the development of these conditions, highlighting their inherent bidirectional relationship. We conclude with a perspective on future research directions for the field of cardio-oncology to advance the care of patients with CVD and cancer.

Elucidating the Cell Surfaceome to Accelerate Cancer Drug Development.

SUMMARY: Cell surface proteins represent ideal therapeutic targets because of their accessibility to antibodies, T cell-directed therapies, and radiotherapies, but there are only 25 therapeutically relevant cell surface targets for which cancer therapies are approved in the United States or European Union. This commentary calls for intensified research into mapping the universe of cell surface proteins - the cell surfaceome - in order to accelerate cancer drug development.

Internal Herniation of the Transverse Colon and Stricture of the Gastric Body: A Case Report.

Internal herniation is a protrusion of the bowel limited to the abdominal cavity. This pathology is rare and difficult to diagnose due to a wide array of symptoms that may manifest. Internal hernias have the potential to affect surrounding organs such as the stomach and adjacent bowel due to the compressive force of the protruding bowel. The effects of internal herniation commonly present in one of two ways: acute obstruction which requires emergent intervention and subacute, vague symptoms that are difficult to diagnose. This case presents the findings of a post-mortem dissection of a 92-year-old willed body donor. Dissection of the abdominal cavity revealed a large internal hernia of the transverse colon that communicated superiorly posterior to the stomach. As a result of the hernia, the stomach in this patient had a stricture of the gastric body. We assert that this stricture was formed over an extended period of time due to the lack of diagnosis and treatment of the internal hernia.

Integrated pain care models and the importance of aligning stakeholder values.

Sustained widespread deployment of clinically and cost-effective models of integrated pain care could be bolstered by optimally aligning shared stakeholder values.

Impact of recipient and donor pretransplantation body mass index on early postosperative complications after lung transplantation.

BACKGROUND: Prior studies have assessed the impact of the pretransplantation recipient body mass index (BMI) on patient outcomes after lung transplantation (LT), but they have not specifically addressed early postoperative complications. Moreover, the impact of donor BMI on these complications has not been evaluated. The first aim of this study was to assess complications during hospitalization in the ICU after LT according to donor and recipient pretransplantation BMI. METHODS: All the recipients who underwent LT at Bichat Claude Bernard Hospital, Paris, between January 2016 and August 2022 were included in this observational retrospective monocentric study. Postoperative complications were analyzed according to recipient and donor BMIs. Univariate and multivariate analyses were also performed. The 90-day and one-year survival rates were studied. P < 0.05 was considered to indicate statistical significance. The Paris-North Hospitals Institutional Review Board approved the study. RESULTS: A total of 304 recipients were analyzed. Being underweight was observed in 41 (13%) recipients, a normal weight in 130 (43%) recipients, and being overweight/obese in 133 (44%) recipients. ECMO support during surgery was significantly more common in the overweight/obese group (p = 0.021), as were respiratory complications (primary graft dysfunction (PGD) (p = 0.006), grade 3 PDG (p = 0.018), neuroblocking agent administration (p = 0.008), prone positioning (p = 0.007)), and KDIGO 3 acute kidney injury (p = 0.036). However, pretransplantation overweight/obese status was not an independent risk factor for 90-day mortality. An overweight or obese donor was associated with a decreased PaO2/FiO2 ratio before organ donation (p < 0.001), without affecting morbidity or mortality after LT. CONCLUSION: Pretransplantation overweight/obesity in recipients is strongly associated with respiratory and renal complications during hospitalization in the ICU after LT.

Eligibility and Projected Benefits of Rapid Initiation of Quadruple Medical Therapy for Newly Diagnosed Heart Failure.

BACKGROUND: U.S. nationwide estimates of the proportion of patients newly diagnosed with heart failure with reduced ejection fraction (HFrEF) eligible for quadruple medical therapy, and the associated benefits of rapid implementation, are not well characterized. OBJECTIVES: This study sought to characterize the degree to which patients newly diagnosed with HFrEF are eligible for quadruple medical therapy, and the projected benefits of in-hospital initiation. METHODS: Among patients hospitalized for newly diagnosed HFrEF in the Get With The Guidelines-Heart Failure registry from 2016 to 2023, eligibility criteria based on regulatory labeling, guidelines, and expert consensus documents were applied for angiotensin receptor-neprilysin inhibitor, beta-blocker, mineralocorticoid receptor antagonist, and sodium-glucose cotransporter 2 inhibitor therapies. Of those eligible, the projected effect of quadruple therapy on 12-month mortality was modeled using treatment effects from pivotal clinical trials utilized by the AHA/ACC/HFSA Guideline for the Management of Heart Failure, and compared with observed outcomes among patients treated with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and beta-blockers. RESULTS: Of 33,036 patients newly diagnosed with HFrEF, 27,158 (82%) were eligible for quadruple therapy, and 30,613 (93%) were eligible for ≥3 components. From 2021 to 2023, of patients eligible for quadruple therapy, 15.3% were prescribed quadruple therapy and 41.5% were prescribed triple therapy. Among Medicare beneficiaries eligible for quadruple therapy, 12-month incidence of mortality was 24.7% and HF hospitalization was 22.2%. Applying the relative risk reductions in clinical trials, complete implementation of quadruple therapy by time of discharge was projected to yield absolute risk reductions in 12-month mortality of 10.4% (number needed to treat = 10) compared with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and beta-blocker, and 24.8% (number needed to treat = 4) compared with no GDMT. CONCLUSIONS: In this nationwide U.S. cohort of patients hospitalized for newly diagnosed HFrEF, >4 of 5 patients were projected as eligible for quadruple therapy at discharge; yet, <1 in 6 were prescribed it. If clinical trial benefits can be fully realized, in-hospital initiation of quadruple medical therapy for newly diagnosed HFrEF would yield large absolute reductions in mortality.

Pleistocene glaciation advances the cryptic speciation of Stellera chamaejasme L. in a major biodiversity hotspot.

The mountains of Southwest China comprise a significant large mountain range and biodiversity hotspot imperiled by global climate change. The high species diversity in this mountain system has long been attributed to a complex set of factors, and recent large-scale macroevolutionary investigations have placed a broad timeline on plant diversification that stretches from 10 million years ago (Mya) to the present. Despite our increasing understanding of the temporal mode of speciation, finer-scale population-level investigations are lacking to better refine these temporal trends and illuminate the abiotic and biotic influences of cryptic speciation. This is largely due to the dearth of organismal sampling among closely related species and populations, spanning the incredible size and topological heterogeneity of this region. Our study dives into these evolutionary dynamics of speciation using genomic and eco-morphological data of Stellera chamaejasme L. We identified four previously unrecognized cryptic species having indistinct morphological traits and large metapopulation of evolving lineages, suggesting a more recent diversification (~2.67-0.90 Mya), largely influenced by Pleistocene glaciation and biotic factors. These factors likely influenced allopatric speciation and advocated cyclical warming-cooling episodes along elevational gradients during the Pleistocene. The study refines the evolutionary timeline to be much younger than previously implicated and raises the concern that projected future warming may influence the alpine species diversity, necessitating increased conservation efforts.

Variation in monthly and seasonal elevation use impacts behavioral and dietary flexibility in Rhinopithecus bieti.

Black-and-white snub-nosed monkeys (Rhinopithecus bieti) rely on behavioral and dietary flexibility to survive in temperate latitudes at high-elevation habitats characterized by climate and resource seasonality. However, little is known about how elevation influences their behavioral and dietary flexibility at monthly or seasonal scales. We studied an isolated R. bieti population at Mt. Lasha in the Yunling Provincial Nature Reserve, Yunnan, China, between May 2008 and August 2016 to assess the impacts of elevation on feeding behavior and diet. Across our sample, R. bieti occupied elevations between 3031 and 3637 m above mean sea level (amsl), with a 315.1 m amsl range across months and a 247.3 m amsl range across seasons. Contrary to expectations, individuals spent less time feeding when ranging across higher elevations. Lichen consumption correlated with elevation use across months and seasons, with individuals spending more time feeding on this important resource at higher elevations. Leaf consumption only correlated with elevation use during the spring. Our results suggest that R. bieti do not maximize their food intake at higher elevations and that monthly and seasonal changes in lichen and leaf consumption largely explain variation in elevation use. These findings shed light on the responses of R. bieti to environmental change and offer insight into strategies for conserving their habitats in the face of anthropogenic disturbance.