Preliminary Feasibility and Acceptability Examination of Using a Novel Ergonomic Chinrest with a Low Shoulder Rest by a Viola Player: A Case Report.

BACKGROUND: High-string players, such as violinists and violists, are prone to neck problems. One factor can be their body posture, with often a rotated and flexed neck position with the jaw placed on a flat chinrest. The Kréddle chinrest (EC) was specifically designed to promote a more neutral neck position and prevent musculoskeletal problems among high-string players. This case report aims to evaluate the preliminary feasibility and acceptability of using the EC, with a low shoulder rest, in a pain-free professional high-string player. A secondary aim was to register newly developed pain and fatigue. METHODS: A 32-year-old professional viola player was instructed to use the EC for most of her playing time during a 6-week trial period. Outcome measures such as compliance (% of use out of total playing time over the last 7 days), performance, comfort and acceptability were assessed at baseline and at the end of each trial week. The Rapid Upper Limb Assessment (RULA) tool was used to evaluate the body posture at baseline when using the EC versus her own chinrest and shoulder rest. RESULTS: The initial trial period was interrupted after 2 days due to pain. A second 6-week period was completed. While compliance was high and there was positive feedback on how the EC affected her performance and comfort while holding the instrument, the case report identified a challenge with the complex instruction material, which made it difficult to install and adjust the product. The viola player was positive towards using EC in the end despite pain and fatigue during the trial period. CONCLUSION: This case report examined a professional viola player's 6-week experience with an EC. While positive outcomes were observed in posture, performance, and product acceptance, issues with complex instructions were noted. This study marks the first exploration of individual challenges with EC use.

The user experience of violinists playing with a novel ergonomic chinrest: An evaluation on motivation, usage behaviour, usability and acceptance.

BACKGROUND: This study focuses on the user experience of a novel developed ergonomic chinrest (EC), customised to accommodate the individual violinist's anthropometry and playing style. The EC was recently tested for biomechanical effect, but the violin player's motivation, usage behaviour, usability and acceptability may be equally important. OBJECTIVE: To explore the user experience of violinists who used the novel EC with a low shoulder rest for two weeks. Through that experience, we wanted to learn about the potential user barriers and facilitators related to their motivation, usage behaviour, usability, and acceptability, when trying a new product. METHODS: Thirty-eight professional violinists participated and evaluated motivation, user behaviour, usability and acceptance using a 5-point Likert scale and open-ended questions. RESULTS: Participants showed high motivation hoping to improve posture, reduce muscle tension and enhance performance. Usage behaviour was also high, while product appearance, adjustment time, and sound impact were negatively evaluated. However, 37% planned to continue to use EC after the study. CONCLUSION: Participants showed high motivation and usage behaviour but faced challenges with product appearance, adjustment time, and sound impact compared to their usual chinrest. Incorporating user feedback and addressing design and usability challenges can enhance the user experience.

Measuring the usability of a novel ergonomic chinrest during violin playing: A feasibility study.

BACKGROUND: Playing the violin often requires a rotated and lateral flexed neck, leading to potential neck and shoulder problems. An ergonomic chinrest (EC) with or without a shoulder rest (SR or WSR) may enhance neutral neck positioning, but the feasibility of the EC needs to be studied. OBJECTIVE: Our goal was to evaluate the usability of the EC for a two-week familiarisation period, including aspects such as playing performance, comfort level, and emotional response (e.g., feelings about using the product) among a group of violinists. METHODS: A one-arm feasibility study was conducted to assess the feasibility of violinists playing with EC every day for two weeks. Six violinists who usually played with SR were included and asked to divide their daily playing time equally between SR and WSR. Feasibility outcomes were measured as adherence (days), compliance (playing hours per day) and usability (5-point Likert scale and open-ended questions). Compliance was achieved with a minimum of 25% playing time. RESULTS: Daily violin playing with EC showed high adherence of 89.3%. Compliance with the 25% play time criterion was met for SR, but not for WSR. Low playing performance (median 45.8 points difference), long confidence time (two violinists failed to reach a confidence level) and mainly negative feedback (26 out of 33 comments) were found in WSR compared to SR. CONCLUSIONS: The feasibility of playing WSR was low and negatively impacted playing performance. As a result, a larger-scale study will only evaluate the EC with SR due to greater feasibility.

Early-life exposure to perfluoroalkyl substances and serum antibody concentrations towards common childhood vaccines in 18-month-old children in the Odense Child Cohort.

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with reduced antibody response to childhood vaccinations. Previous studies have mostly focused on antibodies against diphtheria or tetanus, while fewer studies have assessed antibodies toward attenuated viruses, such as measles, mumps or rubella (MMR). Therefore, we set out to determine associations between prenatal and early postnatal PFAS exposure and vaccine-specific Immunoglobulin G (IgG) in the background-exposed Odense Child Cohort. Blood samples were drawn in pregnancy at gestation weeks 8-16 and from the offspring at age 18 months. In the maternal serum samples we quantified perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA). In the offspring serum samples we quantified the same five PFAS compounds and IgG towards diphtheria, tetanus and MMR. A total of 880 and 841 children were included in the analyses of diphtheria and tetanus or MMR, respectively. Multiple linear regression models were used for estimation of difference in virus-specific IgG per doubling of PFAS concentrations. Maternal PFAS concentrations were non-significantly inversely associated with most vaccine-specific antibody concentrations. Likewise, child PFAS concentrations were associated with non-significant reductions of antibodies towards tetanus and MMR. A significant reduction in the percent difference in mumps antibody concentration per doubling of child PFNA (-9.2% (95% confidence interval: -17.4;-0.2)), PFHxS (-8.3% (-15.0;-1.0) and PFOS (-7.9% (-14.8;-0.4) was found. These findings are of public health concern, as inadequate response towards childhood vaccines may represent a more general immune dysfunction.

Rickettsiosis in Denmark: A nation-wide survey.

Rickettsia helvetica has been reported at varying prevalences in Danish and other European Ixodes ricinus populations. Though apparently widespread and with reported cases of human infection, the significance of the bacteria as a threat to public health remains unclear. We present a nation-wide survey of rickettsia in ticks, roe deer and humans in Denmark. Ticks were collected by flagging and screened for presence of rickettsial DNA by polymerase chain reaction. Sera from roe deer, hunters, neuroborreliosis patients and blood donors were analyzed for presence of anti-R. helvetica and Rickettsia felis antibodies by immunofluorescence microscopy. The Rickettsia minimum infection rate in ticks was 4.9 % (367/973 pools positive, 7510 ticks in total), with 3.9 % in nymphs and 9.3 % in adults. Rickettsia helvetica accounted for 4.17 % and Rickettsia monacensis for 0.03 %, 0.6 % comprised non-differentiable rickettsial DNA. The prevalence of antibodies against R. helvetica was 2.8 % (9/319) in roe deer, while no hunters (n = 536) or blood donors (n = 181) were positive. The prevalence of anti-R. helvetica antibodies among Lyme neuroborreliosis patients was 6 % (3/47), where it co-occurred with Anaplasma phagocytophilum. Based on our study autochthonous rickettsiosis is of limited concern to the public health in Denmark, but our finding of R. monacensis for the first time in Denmark illustrates the dynamic nature of tick-borne pathogens, emphasizing that continuous surveillance is necessary.

The effects of an ergonomic chinrest among professional violin players. A biomechanical investigation in a randomised crossover design.

This study aimed to compare violinists' upper body kinematics and muscle activity while playing with different supportive equipment: their usual chinrest (UC) or an ergonomic chinrest (EC), each mounted on the violin. Three-dimensional motion capture and electromyographic data were acquired from the upper body while 38 pain-free professional violinists performed an excerpt of a music piece. There were only minor differences between the two set-ups tested. The EC resulted in less left rotation of the head (3.3°), slightly more neck extension (1.3°) and less muscle activity (0.5-1.0 %MVE). However, the overall high static muscle activity (4-10 %MVE across all muscles) was maintained using EC. For both setups, the head posture was left-rotated >15°, ≤6° flexed and left-bent 90% of the time. The EC did not produce a substantial difference in biomechanical load. Instead, future studies may focus on aspects other than chinrest design to lower the static workload demands.

Effects of different violin playing techniques on workload in forearm and shoulder muscles.

Due to their working position, violinists are more prone to musculoskeletal pain than other instrumentalists. Playing the violin may cause increased activity in the shoulder and forearm muscles due to techniques such as vibrato (pitch variation), double-fingering (thirds), and changes in speed and volume (piano and forte). This study investigated how the different violin techniques affect muscle activity while playing scales and a music piece. Surface EMG was recorded bilaterally from the upper trapezius and forearm muscles in 18 violinists. Increased playing speed followed by playing with vibrato was the most demanding task affecting the left forearm muscles. Playing forte was the most demanding factor for the right forearm muscles. The music piece and the grand mean of all techniques showed similar workload demands. These results show that specific techniques require higher workload demands and should be considered when planning rehearsals with these techniques as a part of injury prevention.

A Danish national, multicentre evaluation of the new donor vigilance system among different staff groups.

BACKGROUND AND OBJECTIVES: Two years after implementing a new national donor vigilance system, the Danish Haemovigilance Committee conducted a nationwide survey to evaluate the implementation among different staff groups. We present the results here. MATERIALS AND METHODS: The study was designed as an anonymous online survey to evaluate the satisfaction with the new registration, understanding of the parameters used and the user-friendliness. The REDCap platform was used. The questionnaire consisted of 22 questions. Ordinal variables were answered using five-point Likert scale (1 = strongly disagree to 5 = strongly agree). The data were analysed using descriptive statistics. Successful implementation was defined as mean overall satisfaction ≥4 and mean understanding of the individual components (adverse reaction category, severity and imputability) in the registration ≥4. RESULTS: In all, 104 staff members (77.9% donation staff) participated. The mean (SD) overall satisfaction among all participants was 3.96 (0.94), highest among medical doctors (4.43 (0.78)) and lowest for administrative or other personnel (2.78 (1.09)). The mean scores for understanding the adverse reaction categories, severity and imputability were 3.92 (0.94), 3.92 (0.94) and 3.88 (1.00), respectively. Experience with a previous donor vigilance system was associated with lower scores. The most successful implementation programme included a medical doctor for introduction and a contact person. CONCLUSION: The goal for successful implementation was not met. However, the overall attitude towards the new registration was positive and indicates that the system is suitable for different staff groups. Our results suggest that implementation could benefit from special attention to administrative staff and those accustomed to another donor vigilance system.

Workplace Social Capital as Buffer for Emotional Demands and Perceived Stress in Symphony Orchestras: A Danish Cross-Sectional Survey.

INTRODUCTION: High workplace social capital (WSC) is associated with improved occupational health in the common occupational areas. However, little is known on WSC and its effect on the emotional demands and stress seen in the work of classical symphonic musicians. AIM: To investigate whether WSC moderates the associations between emotional demands and stress in the professional musicians working in Danish symphony orchestras. METHODS: This cross-sectional study builds on existing data collected on a sample of 341 Danish classical symphonic musicians. An interaction model based on multiple regression with bias corrected boot-strapping was used to assess the moderating effect of low, medium and high levels of WSC on the association between emotional demands and perceived stress. RESULTS: WSC had a significant moderating effect on the association between emotional demands and perceived stress: b = -0.01, t(212) = -2.40, p = 0.018. At low levels of WSC the effect of emotional demands on stress was strongest, declining at higher levels of WSC in a dose response pattern: low-WSC, b = 0.23, t(212) 3.20, p = 0.002, medium-WSC, b = 0.11, t(212) = 2.40, p = 0.017, and high-WSC, b = 0.04, t(212) = 0.75, p = 0.455. CONCLUSION: The study indicates a buffering effect of WSC on the association between emotional demands and stress in the work of orchestra musicians. Thus, enhancement of WSC could be a potential stress-preventing strategy in symphony orchestras and should be investigated in future studies on musicians' mental health.

The new donor vigilance system in Denmark reveals regional differences in adverse reactions supposedly caused by variation in the registration.

BACKGROUND AND OBJECTIVES: In recent years, there has been an increased focus among blood bank professionals on the health and safety of blood donors. In 2019, the Danish Haemovigilance Committee designed a national donor vigilance system to improve the registration of adverse reactions (AR) in blood donors. The new donor vigilance system was implemented on 1 January 2020 and we here present the results from the first year of registration. MATERIALS AND METHODS: AR categories, severity level and imputability score were defined based on the definitions from the International Society of Blood Transfusion, AABB and the European Commission directive 2005/61/EC, respectively. RESULTS: Across all severity levels, AR in Danish blood donors were found to be rare (1498 per 100,000 donations). Only 0.2% of the registered reactions were classified as serious (2.7 per 100,000 donations). Large regional differences were seen in the registration of citrate reactions and haematomas. CONCLUSION: Significant differences across regions in what to categorize as an AR were persistent even when including a severity score in the reporting. The Danish Haemovigilance Committee will commence a national work to align the definitions but suggests that this matter is raised to an international level as part of the current work to agree upon definitions for assessment of donor AR.

Combinations of self-reported rhinitis, conjunctivitis, and asthma predicts IgE sensitization in more than 25,000 Danes.

BACKGROUND: Allergic rhinitis (AR), allergic conjunctivitis (AC), and asthma composing multiple phenotypes and improved understanding of these phenotypes and their respective risk factors are needed. OBJECTIVES: The objective of this study was to define the prevalence of AR, AC, and asthma and their association with allergen-specific immunoglobulin E (sIgE) sensitization in a large cohort of blood donors and identify risk factors. METHODS: From the nationwide population-based Danish Blood Donor Study, 52,976 participants completed an electronic questionnaire including AR, AC, asthma, allergic predisposition, and childhood residence. Of these, 25,257 were additionally tested for sIgE to inhalation allergens (Phadiatop). RESULTS: The prevalence of sIgE sensitization, AR, AC, and asthma was 30%, 19%, 15%, and 9%, respectively. The youngest birth cohorts had the highest prevalence of sIgE sensitization and symptoms of asthma, AR, and AC, and for asthma, they apparently experienced symptoms at an earlier age. The sIgE sensitization was positively associated with male sex. The sIgE seroprevalence was higher in participants with both AR and AC (ARC) than in participants with either AR or AC. Allergic predisposition and sIgE sensitization increased the risk of the diseases, while farm upbringing was associated with reduced prevalence of ARC, however, only in sIgE sensitized participants. CONCLUSION: Birth year, childhood residence, sIgE sensitization, and allergic predisposition were associated with asthma, AR, and AC prevalence. Individuals with self-reported ARC represent a primarily sIgE-positive phenotype, while those with either AR or AC represent more diverse phenotypes.

A genome-wide meta-analysis yields 46 new loci associating with biomarkers of iron homeostasis.

Iron is essential for many biological functions and iron deficiency and overload have major health implications. We performed a meta-analysis of three genome-wide association studies from Iceland, the UK and Denmark of blood levels of ferritin (N = 246,139), total iron binding capacity (N = 135,430), iron (N = 163,511) and transferrin saturation (N = 131,471). We found 62 independent sequence variants associating with iron homeostasis parameters at 56 loci, including 46 novel loci. Variants at DUOX2, F5, SLC11A2 and TMPRSS6 associate with iron deficiency anemia, while variants at TF, HFE, TFR2 and TMPRSS6 associate with iron overload. A HBS1L-MYB intergenic region variant associates both with increased risk of iron overload and reduced risk of iron deficiency anemia. The DUOX2 missense variant is present in 14% of the population, associates with all iron homeostasis biomarkers, and increases the risk of iron deficiency anemia by 29%. The associations implicate proteins contributing to the main physiological processes involved in iron homeostasis: iron sensing and storage, inflammation, absorption of iron from the gut, iron recycling, erythropoiesis and bleeding/menstruation.

A meta-analysis uncovers the first sequence variant conferring risk of Bell's palsy.

Bell's palsy is the most common cause of unilateral facial paralysis and is defined as an idiopathic and acute inability to control movements of the facial muscles on the affected side. While the pathogenesis remains unknown, previous studies have implicated post-viral inflammation and resulting compression of the facial nerve. Reported heritability estimates of 4-14% suggest a genetic component in the etiology and an autosomal dominant inheritance has been proposed. Here, we report findings from a meta-analysis of genome-wide association studies uncovering the first unequivocal association with Bell's palsy (rs9357446-A; P = 6.79 × 10-23, OR = 1.23; Ncases = 4714, Ncontrols = 1,011,520). The variant also confers risk of intervertebral disc disorders (P = 2.99 × 10-11, OR = 1.04) suggesting a common pathogenesis in part or a true pleiotropy.

Surface electromyography of forearm and shoulder muscles during violin playing.

The aims of this study were to explore muscle activity levels during different violin repertoires, quantify the general levels bilaterally in upper extremity muscles, and evaluate associations between muscle activity and anthropometrics characteristics. In 18 skilled violin players surface EMG was recorded bilaterally from trapezius (UT), flexor digitorum superficialis (FDS), extensor carpi ulnaris (ECU), extensor digitorum cummunis (EDC), and extensor carpi radialis (ECR) during A and E major scales played in three octaves and Mozart's Violin Concerto no. 5. To compare side differences the static, median and peak levels of muscle activity were calculated from an amplitude probability distribution function (APDF). This study demonstrated that scales played as standardized tasks can be used to estimate the average muscle activity during violin playing. Comparing results from scales and the music piece revealed a similar muscle activity across all muscles in the music piece and E major scales. The static, median and peak EMG levels were higher in left than in right forearm muscles with left ECU presenting the highest peak load of 30 %MVE. Females demonstrated a higher muscle activity than males, but this was in accordance with differences in anthropometric measures.

Performance characteristics of thromboelastometry assays using incompletely filled and prolonged stored samples.

BACKGROUND: Thromboelastometry (TEM) is often used to guide transfusion therapy in patients with massive bleeding. The effect of testing incompletely filled samples and those stored for a prolonged time at 4°C was investigated. METHODS: Whole blood samples were collected from 15 healthy blood donors and were pooled according to ABO group. From these pools, aliquots were taken and diluted to produce final whole blood:citrate buffer ratios ranging from 90:10 (fully filled sample) to 40:60 (extremely under filled samples). These samples were then tested by EXTEM, INTEM, and FIBTEM on calibrated ROTEM delta machines. Separately, the four samples at 90:10 dilution were kept at 4°C for 16-20 hours and then retested on the ROTEM machines. RESULTS: All of the samples at the 90:10 and 80:20 (half-filled sample) whole blood:citrate buffer dilutions demonstrated ROTEM parameters within their respective reference ranges, although the samples from the 80:20 dilution tended to demonstrate slightly longer or slower times, depending on each ROTEM parameter, compared to the completely filled samples. All of the samples with more dilute whole blood to citrate buffer ratios (i.e., 70:30 to 40:60) yielded abnormal TEM results. The TEM results for the 90:10 dilution samples exposed to 16-20 hours of storage at 4°C were within the reference intervals. CONCLUSION: Completely and half-filled samples, and completely filled samples after prolonged cold storage, produced normal ROTEM results. Tubes that are less than half-filled should not be used for ROTEM testing.

Prevalence and socio-demographic characteristics of persons who have never had a headache among healthy voluntary blood donors - a population-based study.

INTRODUCTION: Headache is an extremely prevalent disorder with a lifetime prevalence of 90-99%. However, a small fraction of people never experiences a headache. Research on people without headache could uncover protective factors in headache, but to our knowledge no study on headache-free individuals has been published. We aim to estimate the prevalence of headache-free individuals among Danish blood donors, and to describe the socio-demographics and health factors of headache-free participants. MATERIALS AND METHODS: In all, 38,557 healthy volunteers were recruited as part of the Danish Blood Donor Study. Headache-free participants were identified based on the question "Have you ever experienced a headache of any kind?". Utilising the Danish registries and self-reported questionnaires, we analysed socio-demographic and lifestyle factors using logistic regression adjusted for age and sex. RESULTS: The prevalence of headache-free individuals was 4.1% (n = 1362) with a female-male ratio of 1:2.2. To be headache free was significantly associated with an employment status as a student, a low level of income and a regular alcohol consumption. DISCUSSION: The prevalence of headache-free individuals was comparable to population-wide studies of headache. To be headache free was not associated with a high socio-economic status. Further studies on people without headache will hopefully reveal protective factors in headache, and this novel approach might be useful in other very prevalent disorders.

The donors perceived positive and negative effects of blood donation.

BACKGROUND: Occasionally blood donation has a negative influence on some donors, while others express feelings of increased energy or wellbeing after donation. Some donors even report symptoms such as headache or feelings of unease indicating "it is time to donate blood again." This study aims to determine symptoms and frequencies of blood donors experiencing positive and negative effects of blood donation, and study possible associations with sex, age, body mass index, smoking status, and hemoglobin level. STUDY DESIGN AND METHODS: We developed and validated a questionnaire with eight predefined physical and psychological symptoms related to blood donation using a 5-point Likert Scale. Participants in The Danish Blood Donor Study were asked to indicate if they experienced the present symptom prior to and/or after the donation. RESULTS: A total of 6,073 donors were included. Of the donors, 61% experienced one or more effects of blood donation. Positive effects were experienced by 18% of the donors, 29% experienced negative effects, and 14% experienced both. Most notable positive effects were alleviated headache (14%), feeling lighter (14%), and less tiredness (7%). Most notable negative effects were less energy (25%), more dizziness (22%), and more tiredness (21%). Logistic regression analysis revealed that positive effects were more likely among donors with higher BMI, older donors, and smokers. Negative effects were more likely among younger donors, donors with lower BMI, and among female donors. CONCLUSION: Analyses indicate that susceptibility to blood donation effects varies by BMI, sex, smoking status, and age, and therefore should be taken into consideration when informing donors about potential effects of blood donation.

Herpes Simplex Virus Type 1 infection is associated with suicidal behavior and first registered psychiatric diagnosis in a healthy population.

Increasing evidence shows that latent infections and inflammation is associated with cognitive and behavioral changes in humans. This case-control study investigates the association between Herpes Simplex Virus Type 1 (HSV-1) infection and C-reactive Protein (CRP) levels, and psychiatric disorders and suicidal behavior. Public health register data from 81,912 participants in the Danish Blood Donor Study, were reviewed to identify individuals registered with an ICD-10 code of any psychiatric diagnosis, or who had attempted or committed suicide. We found 1,504 psychiatric cases and 353 suicidal cases; for all cases, controls were frequency-matched by age and sex, resulting in 5,336 participants. Plasma samples were analyzed for IgG-class antibodies against HSV-1 and CRP. HSV-1 infection was associated with suicidal behavior (odds-ratio, 1.40; 95% confidence interval [CI] 1.11-1.77). Accounting for temporality, HSV-1 infection was associated with having first psychiatric disorder after the date of blood collection (incidence rate ration, 1.44; 95% CI, 1.05-1.95). No association between CRP and psychiatric disorders or suicidal behavior was found. The finding that HSV-1 was associated with suicidal behavior and first psychiatric disorder indicates that infection may play a role in the etiology and pathogenesis of suicidal behavior and development of psychiatric disorders.

DBDS Genomic Cohort, a prospective and comprehensive resource for integrative and temporal analysis of genetic, environmental and lifestyle factors affecting health of blood donors.

PURPOSE: To establish a cohort that enables identification of genomic factors that influence human health and empower increased blood donor health and safe blood transfusions. Human health is complex and involves several factors, a major one being the genomic aspect. The genomic era has resulted in many consortia encompassing large samples sizes, which has proven successful for identifying genetic factors associated with specific traits. However, it remains a big challenge to establish large cohorts that facilitate studies of the interaction between genetic factors, environmental and life-style factors as these change over the course of life. A major obstacle to such endeavours is that it is difficult to revisit participants to retrieve additional information and obtain longitudinal, consecutive measurements. PARTICIPANTS: Blood donors (n=110 000) have given consent to participate in the Danish Blood Donor Study. The study uses the infrastructure of the Danish blood banks. FINDINGS TO DATE: The cohort comprises extensive phenotype data and whole genome genotyping data. Further, it is possible to retrieve additional phenotype data from national registries as well as from the donors at future visits, including consecutive measurements. FUTURE PLANS: To provide new knowledge on factors influencing our health and thus provide a platform for studying the influence of genomic factors on human health, in particular the interaction between environmental and genetic factors.

Self-reported restless legs syndrome and involuntary leg movements during sleep are associated with symptoms of attention deficit hyperactivity disorder.

BACKGROUND: Restless legs syndrome (RLS) and attention-deficit hyperactivity disorder (ADHD) are disorders with virtually unknown etiologies. Several studies suggest that these disorders are comorbid. However, previous findings may have been influenced by study participants undergoing medical treatments. Thus, the association between RLS and ADHD needs to be investigated in a large population of individuals, not in continuous medical treatment. MATERIALS AND METHODS: This was a cross-sectional study of 25,336 participants enrolled in the Danish Blood Donor Study from May 1, 2015, to February 1, 2017. Study participants completed the Cambridge-Hopkins RLS questionnaire, reported experience of involuntary leg movements during sleep (ILMS), completed the Adult ADHD Self-Report Scale v.1.1 (ASRS), and provided information on sex, age, body mass index, smoking status, alcohol consumption, whole blood donation history, and self-appraised quality of sleep. Associations between RLS and ADHD symptoms, including subtypes, were examined using multivariate linear- and logistic regression analyses. RESULTS: Of the 25,336 participants with complete data, 1,322 (5.2%) were classified with RLS, and 653 (2.6%) experienced ADHD symptoms. RLS sufferers were more prone to classify with ADHD according to the full ASRS (OR = 3.57, 95% CI: 3.14-4.0), and they were also more likely to experience ADHD-subtype symptoms (inattention, OR = 1.66, 95% CI: 1.43-1.90; hyperactivity-impulsivity, OR = 1.90, 95% CI: 1.66-2.14). Finally, RLS sufferers with ILMS had increased odds for ADHD symptoms compared with RLS sufferers without (OR = 2.15, 95% CI: 1.30-3.55). This was also observed for the hyperactivity-impulsivity subtype (OR = 5.57, 95% CI: 2.14-14.5). CONCLUSIONS: RLS and ADHD are associated and may be comorbid disorders.