Psychometric evaluation of the Muscle Dysmorphic Disorder Inventory (MDDI) among cisgender gay men and cisgender lesbian women

Despite increasing empirical interest in muscle dysmorphia (MD), a dearth of research has assessed this construct in sexual minority populations. In particular, the psychometric properties of one of the most widely used measures of MD symptoms—the Muscle Dysmorphic Disorder Inventory (MDDI)—have not been evaluated in sexual minority populations despite emerging evidence suggesting differential risk for MD symptoms across sexual orientation groups. In this study, we assessed the psychometric properties of the MDDI in a sample of 715 cisgender gay men and 404 cisgender lesbian women ages 18–50 years who participated in a large-scale national longitudinal cohort study of sexual and gender minority adults. The factor structure of the MDDI was examined in each sample using a two-step, split-sample exploratory and confirmatory factor analytic approach. Exploratory factor analysis supported a three-factor structure in both samples, which were confirmed by confirmatory factor analysis. Moreover, results supported the internal consistency reliability and convergent validity of the MDDI subscales in both samples. Cumulatively, these findings suggest that the MDDI is an appropriate measure of MD symptoms among cisgender gay men and cisgender lesbian women

Associations among romantic and sexual partner history and muscle dysmorphia symptoms, disordered eating, and appearance- and performance-enhancing drugs and supplement use among cisgender gay men

This study examined relationship status (e.g., single versus not single) and number of sexual partners in relation to muscularity- and disordered eating-related attitudes and behaviors among 1090 cisgender gay men enrolled in The PRIDE Study in 2018. Participants completed measures assessing muscle dysmorphia (MD) symptoms, disordered eating attitudes and behaviors, and appearance- and performance-enhancing drug or supplement (APEDS) use. In linear regression models adjusting for theoretically relevant covariates, neither relationship status nor number of past-month sexual partners was associated with disordered eating attitudes. In terms of MD symptoms, single (versus not single) relationship status was associated with greater appearance intolerance, and a greater number of sexual partners was associated with greater drive for size and functional impairment. In adjusted logistic regression models, a greater number of past-month sexual partners was associated with use of anabolic-androgenic steroids, synthetic performance-enhancing substances, protein supplements, and creatine supplements, as well as greater likelihood of engaging in compelled/driven exercise. Across all associations, effect sizes were generally small. Overall, results support that inquiring about sexual partners may have utility in evaluating risk for muscularity-oriented attitudes and behaviors among cisgender gay men. Future work will need to replicate these findings, particularly in more diverse samples

Community norms of the Muscle Dysmorphic Disorder Inventory (MDDI) among cisgender sexual minority men and women

Abstract Background Representing the pathological extreme pursuit of muscularity, muscle dysmorphia (MD) is characterized by a pervasive belief or fear around insufficient muscularity and an elevated drive for muscularity. Despite evidence of elevated body image-related concerns among sexual minority populations, little is known about the degree of muscle dysmorphia (MD) symptoms among sexual minorities, particularly based on Muscle Dysmorphic Disorder Inventory (MDDI) scores. The objective of this study was to examine the nature and severity of MD symptoms in cisgender sexual minority men and women and provide community norms of the MDDI for these populations. Methods Data from participants in The PRIDE Study, an existing study of health outcomes in sexual and gender minority people from the United States, were examined. Participants included cisgender gay men (N = 1090), cisgender bisexual plus (bisexual, pansexual, and/or polysexual) men (N = 100), cisgender lesbian women (N = 563), and cisgender bisexual plus women (N = 507). We calculated means, standard deviations (SD), and percentiles for the MDDI total and subscale scores for cisgender sexual minority men and women. We compared MDDI scores by sexual orientation using linear regression models, both unadjusted and adjusted for sociodemographics. Results Overall, the sample was 85.2% White, 3.0% Asian or Pacific Islander, 2.0% Black, 0.5% Native American, 3.9% multiracial, and 6.6% Hispanic/Latino/a. The mean age was 38.6 (SD = 14.3) and 69.4% had a college degree or higher. Means (SD) for the MDDI total score were 27.4 (7.7) for cisgender gay men, 26.4 (6.4) for cisgender bisexual plus men, 24.3 (6.1) for cisgender lesbian women, and 24.6 (5.5) for cisgender bisexual plus women. There were no significant differences in MDDI scores between cisgender gay and bisexual plus men, or between cisgender lesbian women and bisexual plus women in unadjusted or adjusted models. Conclusions These normative data provide insights into the experience of MD symptoms among cisgender sexual minority men and women and can aid researchers and clinicians in the evaluation of MD symptoms and interpretation of MDDI scores in sexual minority populations

Psychometric evaluation of the muscle dysmorphic disorder inventory (MDDI) among gender-expansive people.

PurposeMuscle dysmorphia is generally classified as a specific form of body dysmorphic disorder characterized by a pathological drive for muscularity and the preoccupation that one is too small or not sufficiently muscular. The majority of research on the condition has been conducted in cisgender men with a paucity of literature on gender minority people, a population that is at risk for muscle dysmorphia. One of the most widely used measures of muscle dysmorphia symptoms, the Muscle Dysmorphic Disorder Inventory (MDDI), has not been psychometrically validated for use in gender minority samples, the aim of the present study.MethodsWe evaluated the psychometric properties of the MDDI in a sample of 1031 gender-expansive individuals (gender minority people whose gender identity differs from that assumed for their sex assigned at birth and is not exclusively binary man or woman) aged 18-74 who were part of The PRIDE Study, a large-scale, U.S., longitudinal cohort study.ResultsUsing a two-step, split-sample exploratory and confirmatory factor analytic approach, we found support for the original three-factor structure of the measure. The subscales showed adequate internal consistency, and convergent validity was supported based on significant associations of the MDDI subscale scores with theoretically related scores on a widely used measure of disordered eating.ConclusionsThese findings provided novel support for adequate psychometric properties of the MDDI in a sample of gender-expansive individuals, facilitating the use of this measure in future research on muscle dysmorphia in this understudied and at-risk population

Associations among romantic and sexual partner history and muscle dysmorphia symptoms, disordered eating, and appearance- and performance-enhancing drugs and supplement use among cisgender gay men

This study examined relationship status (e.g., single versus not single) and number of sexual partners in relation to muscularity- and disordered eating-related attitudes and behaviors among 1090 cisgender gay men enrolled in The PRIDE Study in 2018. Participants completed measures assessing muscle dysmorphia (MD) symptoms, disordered eating attitudes and behaviors, and appearance- and performance-enhancing drug or supplement (APEDS) use. In linear regression models adjusting for theoretically relevant covariates, neither relationship status nor number of past-month sexual partners was associated with disordered eating attitudes. In terms of MD symptoms, single (versus not single) relationship status was associated with greater appearance intolerance, and a greater number of sexual partners was associated with greater drive for size and functional impairment. In adjusted logistic regression models, a greater number of past-month sexual partners was associated with use of anabolic-androgenic steroids, synthetic performance-enhancing substances, protein supplements, and creatine supplements, as well as greater likelihood of engaging in compelled/driven exercise. Across all associations, effect sizes were generally small. Overall, results support that inquiring about sexual partners may have utility in evaluating risk for muscularity-oriented attitudes and behaviors among cisgender gay men. Future work will need to replicate these findings, particularly in more diverse samples

The case for using mapped exonic non-duplicate reads when reporting RNA-sequencing depth: examples from pediatric cancer datasets.

BackgroundThe reproducibility of gene expression measured by RNA sequencing (RNA-Seq) is dependent on the sequencing depth. While unmapped or non-exonic reads do not contribute to gene expression quantification, duplicate reads contribute to the quantification but are not informative for reproducibility. We show that mapped, exonic, non-duplicate (MEND) reads are a useful measure of reproducibility of RNA-Seq datasets used for gene expression analysis.FindingsIn bulk RNA-Seq datasets from 2,179 tumors in 48 cohorts, the fraction of reads that contribute to the reproducibility of gene expression analysis varies greatly. Unmapped reads constitute 1-77% of all reads (median [IQR], 3% [3-6%]); duplicate reads constitute 3-100% of mapped reads (median [IQR], 27% [13-43%]); and non-exonic reads constitute 4-97% of mapped, non-duplicate reads (median [IQR], 25% [16-37%]). MEND reads constitute 0-79% of total reads (median [IQR], 50% [30-61%]).ConclusionsBecause not all reads in an RNA-Seq dataset are informative for reproducibility of gene expression measurements and the fraction of reads that are informative varies, we propose reporting a dataset's sequencing depth in MEND reads, which definitively inform the reproducibility of gene expression, rather than total, mapped, or exonic reads. We provide a Docker image containing (i) the existing required tools (RSeQC, sambamba, and samblaster) and (ii) a custom script to calculate MEND reads from RNA-Seq data files. We recommend that all RNA-Seq gene expression experiments, sensitivity studies, and depth recommendations use MEND units for sequencing depth

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Letter to the editor