Course and outcome in individuals with atypical anorexia nervosa: Findings from the Study of Refeeding to Optimize iNpatient Gains (StRONG).

OBJECTIVE: We previously reported that participants with atypical anorexia nervosa (atypical AN) had higher historical and admission weights, greater eating disorder psychopathology, but similar rates of amenorrhea and weight suppression at baseline as compared to anorexia nervosa (AN); here, we compare 1-year outcomes. METHOD: Weight, % median body mass index (%mBMI), Eating Disorder Examination Questionnaire (EDE-Q) scores, resumption of menses, and rehospitalizations were examined at 3, 6, and 12 months post-discharge. Analyses (N = 111) compared changes in %mBMI, weight suppression, and EDE-Q scores over time between atypical AN and AN. RESULTS: Among the participants (48 atypical AN, 63 AN), both groups gained weight but those with atypical AN had lower gains than those with AN in %mBMI (p = .02) and greater weight suppression (p = .002) over time. EDE-Q scores improved over time, independent of weight suppression, with no significant difference between atypical AN and AN. Groups did not differ by rates of resumption of menses (80% atypical AN, 76.9% AN) or rehospitalization (29.2% atypical AN, 37.9% AN). Greater weight suppression predicted longer time to restore menses and more days of rehospitalization. DISCUSSION: Individuals with atypical AN regained a smaller proportion of body mass and were more weight suppressed over time. Change in eating disorder cognitions, resumption of menses, and rehospitalization rates at 1-year follow-up did not differ between groups. There was no significant difference in weight suppression between groups for those who were psychologically improved at 12 months. Findings highlight limitations in our understanding of weight recovery in atypical AN. New metrics for recovery are urgently needed. PUBLIC SIGNIFICANCE: Little is known about outcome in atypical anorexia nervosa (atypical AN). We examined recovery metrics in young people with atypical AN and anorexia nervosa (AN) 1 year after medical hospitalization. Individuals with atypical AN showed slower weight gain and remained further from their pre-illness weight. There were no differences in the rates of psychological recovery, resumption of menses, or rehospitalization. New metrics are needed to assess recovery in atypical AN.

Time to revisit the definition of atypical anorexia nervosa.

In this special issue, international researchers investigate how atypical anorexia nervosa (atypical AN) differs from anorexia nervosa (AN) and other eating disorders with respect to demographics, psychological and physiological morbidity, as well as treatment course and outcome. Manuscripts in this special issue report that atypical AN is associated with substantial medical and psychological morbidity, and the majority of studies find few differences between atypical AN and AN. While much remains to be learned about the long-term course and treatment response of individuals with atypical AN to psychological and pharmacological interventions, the evidence supports conceptualization of atypical AN as part of a spectrum-based restrictive eating disorder. These findings together with the potentially stigmatizing use of the term "atypical" suggest it may be time to revise the existing definition of atypical AN.

Distinguishing probable atypical anorexia nervosa from weight loss alone in a national sample of U.S. Military Veterans: Disentangling the roles of weight suppression and cognitive concerns.

OBJECTIVE: Veterans are at high risk for eating disorders (EDs), and specifically for atypical anorexia nervosa (atypical AN). The current study aimed to better understand this under-studied disorder and how it differs from weight loss without ED cognitive features. METHOD: Secondary analyses were conducted with data from a national study of Veterans (N = 882, 49.4% women). Participants were categorized into four mutually exclusive groups using the Eating Disorder Diagnostic Scale 5: probable atypical AN, a cognitive concerns group (Cog Only), a weight suppressed group (WS Only), and a no ED control group. Adjusted regression models were used to compare groups on measures of eating pathology and mental health. Three weight suppression thresholds (5%, 10%, and 15%) for probable atypical AN were also tested. RESULTS: The sample was comprised of 12% probable atypical AN, 23.6% Cog Only, 16.3% WS Only, and 48.1% Control. The probable atypical AN group was most like the Cog Only group except for higher levels of dietary restraint. Atypical AN fared worse and was least like the Control group followed by the WS Only group. All weight suppression thresholds significantly predicted dietary restraint, with 5% being the best predictor. DISCUSSION: Results found that probable atypical AN is a distinct clinical entity and that the exact weight suppression threshold associated with atypical AN is less important than having any weight suppression. Findings highlight the clinical significance of atypical AN and the importance of gaining a better understanding of how to address this clinical entity. PUBLIC SIGNIFICANCE: Atypical anorexia nervosa is a relatively underexamined but highly prevalent eating disorder in the Veteran population. Results show that ED cognitive features are more closely linked to clinically significant eating pathology and poor mental health than weight suppression alone suggesting that negative thinking about weight gain and appearance, regardless of the presence or severity of weight loss, may signal the need for specialized intervention.

Deficits in volumetric bone mineral density, bone microarchitecture, and estimated bone strength in women with atypical anorexia nervosa compared to healthy controls.

OBJECTIVE: Anorexia nervosa is associated with low bone mineral density (BMD) and deficits in bone microarchitecture and strength. Low BMD is common in atypical anorexia nervosa, in which criteria for anorexia nervosa are met except for low weight. We investigated whether women with atypical anorexia nervosa have deficits in bone microarchitecture and estimated strength at the peripheral skeleton. METHOD: Measures of BMD and microarchitecture were obtained in 28 women with atypical anorexia nervosa and 27 controls, aged 21-46 years. RESULTS: Mean tibial volumetric BMD, cortical thickness, and failure load were lower, and radial trabecular number and separation impaired, in atypical anorexia nervosa versus controls (p < .05). Adjusting for weight, deficits in tibial cortical bone variables persisted (p < .05). Women with atypical anorexia nervosa and amenorrhea had lower volumetric BMD and deficits in microarchitecture and failure load versus those with eumenorrhea and controls. Those with a history of overweight/obesity or fracture had deficits in bone microarchitecture versus controls. Tibial deficits were particularly marked. Less lean mass and longer disease duration were associated with deficits in high-resolution peripheral quantitative computed tomography (HR-pQCT) variables in atypical anorexia nervosa. DISCUSSION: Women with atypical anorexia nervosa have lower volumetric BMD and deficits in bone microarchitecture and strength at the peripheral skeleton versus controls, independent of weight, and particularly at the tibia. Women with atypical anorexia nervosa and amenorrhea, less lean mass, longer disease duration, history of overweight/obesity, or fracture history may be at higher risk. This is salient as deficits in HR-pQCT variables are associated with increased fracture risk. PUBLIC SIGNIFICANCE: Atypical anorexia nervosa is a psychiatric disorder in which psychological criteria for anorexia nervosa are met despite weight being in the normal range. We demonstrate that despite weight in the normal range, women with atypical anorexia nervosa have impaired bone density, structure, and strength compared to healthy controls. Whether this translates to an increased risk of incident fracture in this population requires further investigation.

Comparing the knowledge, attitudes, and practices of pediatric and family medicine clinicians toward atypical anorexia nervosa versus anorexia nervosa.

OBJECTIVE: To investigate the knowledge, attitudes, and current practices of adolescent primary care providers regarding the epidemiology, clinical features, and diagnosis of atypical anorexia nervosa (AN) compared to AN. METHODS: An online survey was sent to the Pediatric and Family Medicine clinicians who provide medical care to adolescents. Statistical analyses compared differences in responses to questions about atypical AN versus AN. RESULTS: Relative to AN, participants (n = 67) were significantly less familiar with atypical AN, less likely to consider a diagnosis of atypical AN, less comfortable identifying atypical AN, less likely to counsel patients with atypical AN on health risks, less likely to refer patients with atypical AN to a specialist, and less likely to correctly identify atypical AN. Clinicians with more years in medical practice reported a significantly larger gap in familiarity between AN and atypical AN than clinicians with less than 5 years of practice. CONCLUSIONS: Providers who care for adolescents appear to be less familiar with and less likely to identify atypical AN compared to AN. This knowledge gap may be more pronounced among clinicians with more years practicing medicine due to the novelty of atypical AN as a diagnosis. Lack of knowledge surrounding atypical AN risk factors may result in delayed diagnosis and associated poor health outcomes. Future research should investigate strategies that improve knowledge and screening of atypical AN in medical and other settings. PUBLIC SIGNIFICANCE: Pediatric and Family Medicine clinicians are less familiar with atypical anorexia nervosa (AN) and less likely to diagnose a patient with atypical AN relative to AN. Insufficient knowledge about atypical AN may place these individuals at increased risk for worsening restrictive eating and the physical and psychological consequences of malnutrition.

Few differences in psychiatric comorbidities and treatment response among people with anorexia nervosa and atypical anorexia nervosa.

OBJECTIVE: Little is known about how individuals with atypical anorexia nervosa (AN) respond to eating disorder (ED) treatment in a partial hospitalization program (PHP), nor how certain factors such as trauma, childhood abuse, psychiatric comorbidity, and suicidal thoughts and behaviors might contribute to poor treatment outcomes. Thus, the current study (1) compares prevalence of these factors between individuals with AN and atypical AN upon admission to an ED PHP, (2) compares PHP treatment response between groups, and (3) investigates whether experiencing these factors impacts treatment outcomes. METHOD: We conducted a retrospective chart review of young adults admitted to a PHP with AN (n = 95) and atypical AN (n = 59). Histories of psychiatric comorbidities and adverse childhood experiences were obtained from initial psychiatric evaluations. ED symptoms were assessed at intake and discharge with the Eating Disorder Examination-Questionnaire (EDE-Q). RESULTS: No significant differences were found at intake in ED symptom severity or prevalence of lifetime trauma, childhood abuse, number of psychiatric diagnoses, or suicidal thoughts and behavior. Symptomatology at discharge also did not differ between groups. Emotional abuse was significantly related to discharge shape and weight overvaluation. No other intake characteristics were significantly related to discharge symptomatology. DISCUSSION: To our knowledge, this is the first study to compare the prevalence of comorbidities for both AN and atypical AN, as well as differential treatment outcomes for these individuals in a PHP. Results add to growing literature suggesting that, other than weight, AN and atypical AN have few properties that reliably distinguish them from one another. PUBLIC SIGNIFICANCE: This study adds to a growing body of literature that raises questions about whether anorexia nervosa (AN) and atypical AN are truly different diagnoses. Our findings suggest these two groups present to treatment in a partial hospitalization program (PHP) with similar ED symptoms, as well as prevalence of lifetime trauma, childhood abuse, suicidal thoughts and behavior, and number of psychiatric comorbidities, and demonstrate similar treatment trajectories in PHP.

Prevalence and risk factors associated with low bone mineral density in Asian adolescents with anorexia nervosa and atypical anorexia nervosa.

OBJECTIVE: This retrospective study aimed to evaluate the prevalence and risk factors for low bone mineral density (BMD) at diagnosis in Asian adolescent females with anorexia nervosa (AN) and atypical AN. METHOD: We analyzed the BMD results for 213 patients between 10 and 18 years of age, with AN and atypical AN receiving care at a pediatric hospital in Singapore. We used linear regression analyses to determine if type of eating disorder, premorbid weight, and duration of amenorrhea were risk factors for low BMD. For a subset of patients with repeat BMD evaluation, we used paired t-tests to assess the impact of weight or menstrual restoration on the change in BMD. RESULTS: The prevalence of BMD height-for-age Z-scores <-2 at presentation was higher in patients with AN (13.0%) than atypical AN (2.3%) (p = .034). In multivariate regression, a diagnosis of atypical AN was protective against low BMD at the lumbar spine (B = 0.394, p = .009) and total body less head (B = 0.774, p = .010). Duration of amenorrhea was not associated with BMD across all sites. For those with repeat BMD measures, there was significantly less deterioration in the BMD Z-scores for patients with weight or menstrual restoration (R = -0.22 ± 0.59, NR = -0.69 ± 0.43, p = .029). CONCLUSIONS: Duration of amenorrhea was not associated with BMD in this sample. A diagnosis of AN was correlated with lower BMD than atypical AN. Further research is needed to better understand the relationship between amenorrhea, weight status, and bone health in Asian adolescents with eating disorders. PUBLIC SIGNIFICANCE: In this sample, 13% of Asian adolescents with AN and 2.3% of Asian adolescents with atypical AN have low BMD. In our study population, duration of amenorrhea was not correlated with BMD. Among adolescents with AN, a history of being underweight at the highest pre-morbid BMI, is correlated with low BMD. It is important for physicians to take a thorough weight history in evaluating bone health in this population.

Differentiation between atypical anorexia nervosa and anorexia nervosa using machine learning.

OBJECTIVE: Body mass index (BMI) is the primary criterion differentiating anorexia nervosa (AN) and atypical anorexia nervosa despite prior literature indicating few differences between disorders. Machine learning (ML) classification provides us an efficient means of accurately distinguishing between two meaningful classes given any number of features. The aim of the present study was to determine if ML algorithms can accurately distinguish AN and atypical AN given an ensemble of features excluding BMI, and if not, if the inclusion of BMI enables ML to accurately classify between the two. METHODS: Using an aggregate sample from seven studies consisting of individuals with AN and atypical AN who completed baseline questionnaires (N = 448), we used logistic regression, decision tree, and random forest ML classification models each trained on two datasets, one containing demographic, eating disorder, and comorbid features without BMI, and one retaining all features and BMI. RESULTS: Model performance for all algorithms trained with BMI as a feature was deemed acceptable (mean accuracy = 74.98%, mean area under the receiving operating characteristics curve [AUC] = 74.75%), whereas model performance diminished without BMI (mean accuracy = 59.37%, mean AUC = 59.98%). DISCUSSION: Model performance was acceptable, but not strong, if BMI was included as a feature; no other features meaningfully improved classification. When BMI was excluded, ML algorithms performed poorly at classifying cases of AN and atypical AN when considering other demographic and clinical characteristics. Results suggest a reconceptualization of atypical AN should be considered. PUBLIC SIGNIFICANCE: There is a growing debate about the differences between anorexia nervosa and atypical anorexia nervosa as their diagnostic differentiation relies on BMI despite being similar otherwise. We aimed to see if machine learning could distinguish between the two disorders and found accurate classification only if BMI was used as a feature. This finding calls into question the need to differentiate between the two disorders.

Examining the placement of atypical anorexia nervosa in the eating disorder diagnostic hierarchy relative to bulimia nervosa and binge-eating disorder.

OBJECTIVE: Some individuals meet the criteria for atypical anorexia nervosa and another eating disorder simultaneously. The current study evaluated whether allowing a diagnosis of atypical anorexia nervosa to supersede a diagnosis of bulimia nervosa (BN) or binge-eating disorder (BED) provided additional information on psychological functioning. METHODS: Archival data from 650 university students (87.7% female, 69.4% white) who met Eating Disorder Diagnostic Survey for DSM-5 eating disorder criteria and completed questionnaires assessing quality of life, eating disorder-related impairment, and/or eating pathology at a single time point. Separate regression models used diagnostic category to predict quality of life and impairment. Two diagnostic schemes were used: the DSM-5 diagnostic scheme and an alternative scheme where atypical anorexia nervosa superseded all diagnoses except anorexia nervosa. Model fit was compared using the Davidson-Mackinnon J test. Analyses were pre-registered (https://osf.io/2ejcd). RESULTS: Allowing an atypical anorexia nervosa diagnosis to supersede a BN or BED diagnosis provided better fit to the data for eating disorder-related impairment (p = .02; n = 271), but not physical, psychological, or social quality of life (p's ≥ .33; n = 306). Allowing an atypical anorexia nervosa diagnosis to supersede a BN or BED diagnosis provided a better fit in cross-sectional models predicting purging (p = .02; n = 638), but not body dissatisfaction, binge eating, restricting, or excessive exercise (p's ≥ .08; n's = 633-647). DISCUSSION: The current data support retaining the DSM-5 diagnostic scheme. More longitudinal work is needed to understand the predictive validity of the atypical anorexia nervosa diagnosis. PUBLIC SIGNIFICANCE: The current study examined how changes to the diagnostic categories for eating disorders may change how diagnoses are associated with quality of life and impairment. Overall, findings suggest that the diagnostic hierarchy should be maintained.

Predictors of psychopathology response in atypical anorexia nervosa following inpatient treatment: A propensity score matching study of weight suppression and weight loss speed.

INTRODUCTION: This study examines weight suppression (WS) and weight loss speed (WLS) in atypical anorexia nervosa (AN) and its implications for treatment outcomes, compared to people with AN and bulimia nervosa (BN). METHOD: A mixed cross-sectional and prospective design was employed, assessing WS and WLS in people with atypical AN, AN, and BN. Participants were matched for age, gender, age of onset, and disorder duration. Clinical measurements and eating disorders questionnaire (EDE-Q) scores were employed to evaluate the response to treatment. RESULTS: Individuals with atypical individuals exhibited WS patterns similar to AN, distinct from BN. Rapid WLS predicted clinical responses in atypical AN and BN, underscoring its treatment relevance. Atypical AN showed higher eating psychopathology scores than AN or BN, emphasizing the need for a reframed diagnosis. DISCUSSION: Understanding atypical AN's connection to restrictive behaviors and weight loss informs screening, assessment, and treatment practices. Recognition of atypical AN's severity and adoption of tailored approaches are essential for recovery. This study highlights the significance of WS and WLS in atypical AN treatment outcomes, offering insights into clinical practice and care. The proposal to reframe atypical AN as a restrictive eating disorder emphasizes its clinical relevance. PUBLIC SIGNIFICANCE STATEMENT: The phenomenon of weight suppression, involving the discrepancy between past highest weight and current weight, has garnered attention due to cultural pressures emphasizing fitness and appearance. This study focuses on its implications in atypical anorexia nervosa, aiming to uncover the relationship between WS, its speed, and treatment outcomes. The investigation contributes insights into tailored interventions for atypical anorexia nervosa and enriches the understanding of this complex disorder's dynamics.

Affective processes underlying restrictive eating in atypical anorexia nervosa: Comparisons to anorexia nervosa and bulimia nervosa using ecological momentary assessment.

OBJECTIVE: Certain symptom and risk/maintenance factor similarities between individuals with atypical anorexia nervosa (AN) and 'typical' AN have been documented, but few studies have investigated how atypical AN compares to bulimia nervosa (BN). Further, the role of affective mechanisms in maintaining restrictive eating in atypical AN has not been examined. The current study investigated whether atypical AN resembles AN and/or BN on affect-related processes using questionnaires and ecological momentary assessment (EMA). METHOD: Women with atypical AN (n = 24), AN-restrictive subtype, (n = 27), AN-binge eating/purging subtype (n = 34), and BN (n = 58) completed questionnaires measuring depressive symptoms and emotion regulation difficulties. They also completed a 14-day EMA protocol during which they reported negative and positive affect and skipped meals five times/day (signal-contingent surveys) and restrictive eating after meals/snacks (event-contingent surveys). RESULTS: Diagnostic groups generally did not differ on questionnaire measures nor affective patterns surrounding restrictive eating behaviors. Momentary changes in affect did not predict or follow restriction at meals/snacks, though higher momentary negative affect ratings predicted skipped meals, and higher positive affect was reported after skipped meals. Greater average negative affect and lower average positive affect predicted both restrictive eating behaviors. DISCUSSION: Across diagnoses, reductions in food intake do not appear to be influenced by momentary changes in affect, though skipping meals may serve an emotion regulation function. Atypical AN seems to resemble AN and BN on affective processes underlying restrictive eating, raising further questions regarding the unique diagnosis of atypical AN. PUBLIC SIGNIFICANCE: Though atypical anorexia appears to strongly resemble anorexia nervosa, it is less clear how this disorder relates to bulimia nervosa. It is further unknown whether affective-related processes underlie restrictive eating in atypical anorexia nervosa, and how these processes compare to those in anorexia nervosa and bulimia nervosa. Results suggest that atypical anorexia does not differ from anorexia nervosa or bulimia nervosa on emotion-related measures, nor in affective patterns surrounding restrictive eating behaviors.

Naturalistic symptom trajectories of atypical anorexia nervosa, anorexia nervosa, and bulimia nervosa in a prospective cohort study of United States college students.

OBJECTIVE: Research on the natural course of symptoms of atypical anorexia nervosa (AN) relative to AN and bulimia nervosa (BN) is limited yet needed to inform nosology and improve understanding of atypical AN. This study aimed to 1) characterize trajectories of eating disorder and internalizing (anxiety, depression) symptoms in college students with and without a history of atypical AN, AN, and BN; and 2) compare sex and race/ethnicity distributions across groups. METHOD: United States college students who participated in Spit for Science™, a prospective cohort study, were classified as having a history of atypical AN (n = 125), AN (n = 160), BN (n = 617), or as non-eating-disorder controls (NCs, n = 5876). Generalized and linear mixed-effects models assessed group differences in eating and internalizing symptom trajectories, and logistic regression compared groups on sex and race/ethnicity distributions. RESULTS: Atypical AN participants demonstrated elevated eating disorder and internalizing symptoms compared to NCs during college, but less severe symptoms than AN and BN participants. Although all eating disorder groups showed signs of improvement in fasting and driven exercise, purging and depression remained elevated. Atypical AN participants showed increasing anxiety and stable binge-eating trajectories compared to AN and/or BN participants. The atypical AN group comprised significantly more people of color than the AN group. DISCUSSION: Findings underscore that atypical AN is a severe psychiatric disorder. As atypical AN may present as less severe than AN and BN and disproportionately affects people of color, clinicians should be mindful of biases that could delay diagnosis and care. PUBLIC SIGNIFICANCE: College students with histories of atypical AN, AN, and BN demonstrated improvements in fasting and driven exercise and stable purging and depression levels. Atypical AN students showed worsening anxiety and stable binge-eating trajectories compared to favorable changes among AN and BN students. A higher percentage of atypical AN (vs. AN) students were people of color. Findings may improve the detection of atypical AN in college students.

Clinical characteristics of hospitalized male adolescents and young adults with atypical anorexia nervosa.

OBJECTIVE: To describe the clinical characteristics of male adolescents and young adults hospitalized for medical complications of atypical anorexia nervosa (atypical AN) and to compare their clinical characteristics with females with atypical AN and males with anorexia nervosa (AN). METHOD: A retrospective review of electronic medical records for patients with atypical AN and AN aged 9-25 admitted to the UCSF Eating Disorders Program from May 2012 to August 2020 was conducted. RESULTS: Among 21 males with atypical AN (mean age 15.1 ± 2.7, mean %mBMI 102.0 ± 11.8), medical complications evidenced by admission laboratory values included anemia (52.9%), vitamin D insufficiency/deficiency (52.6%), and zinc deficiency (31.6%). Compared with females with atypical AN (n = 69), males with atypical AN had longer length of stay (11.4 vs 8.4 days, p = .004), higher prescribed kcal at discharge (4114 vs 3045 kcal, p < .001), lower heart rate nadir (40.0 vs 45.8, p = .038), higher aspartate transaminase (AST, 37.9 vs 26.2 U/L, p = .032), higher alanine transaminase (ALT, 30.6 vs 18.3 U/L, p = .005), and higher rates of anemia (52.9% vs 19.4%, p = .005), with no differences in vitamin D, zinc, and vital signs. Compared with males with AN (n = 40), males with atypical AN had no significant differences in vital signs or laboratory assessments during the hospitalization. DISCUSSION: Atypical AN in males leads to significant medical comorbidity, and males with atypical AN require longer hospital stays compared to females with atypical AN. Rates of abnormal vital signs and abnormal serum laboratory values during hospital admissions do not differ in males with atypical AN compared to AN. PUBLIC SIGNIFICANCE: Adolescent and young adult males with atypical anorexia nervosa experience significant medical complications. Males with atypical anorexia nervosa had longer hospitalizations and higher prescribed nutrition at discharge than females. Medical complications of atypical anorexia nervosa in male adolescents and young adults were generally equal to those of male adolescents and young adults with anorexia nervosa. Clinicians should be aware of unique medical complications of males with atypical anorexia nervosa.

Understanding community provider practices in diagnosing and treating atypical anorexia nervosa: A mixed methods study.

OBJECTIVE: There is a lack of consensus in defining "significant weight loss" when diagnosing atypical anorexia nervosa (atypical AN) and no guidelines exist for setting target weight (TW). The current study aimed to identify community providers' practices related to the diagnosis of atypical AN and the determination of TW. A secondary aim was to evaluate whether professional discipline impacted "significant weight loss" definitions. METHOD: A variety of providers (N = 141; 96.4% female) completed an online survey pertaining to diagnostic and treatment practices with atypical AN. Descriptive statistics were computed to characterize provider-based practices and Fisher's exact tests were used to test for differences in diagnostic practices by professional discipline. Thematic analysis was used to examine open-ended questions. RESULTS: Most (63.97%) providers diagnosed atypical AN in the absence of any weight loss if other AN criteria were met, but doctoral-level psychologists and medical professionals were less likely to do so compared to nutritional or other mental health professionals. Most providers found weight gain was only sometimes necessary for atypical AN recovery. Qualitative responses revealed providers found atypical AN to be a stigmatizing label that was not taken seriously. Providers preferred to use an individualized approach focused on behaviors, rather than weight when diagnosing and treating atypical AN. DISCUSSION: Lack of diagnostic clarity and concrete treatment guidelines for atypical AN may result in substantial deviations from the DSM-5-TR criteria in real-world practice. Clinically useful diagnostic definitions for restrictive eating disorders and evidence-based treatment guidelines for TW and/or other relevant recovery metrics are needed. PUBLIC SIGNIFICANCE: The current study found variability in how community providers diagnose and determine target recovery weight for atypical anorexia nervosa (atypical AN). Many providers viewed the diagnosis of atypical AN as stigmatizing and preferred to focus on behaviors, rather than weight. This study underscores the importance of creating a clinically useful diagnostic definition and guidelines for recovery for atypical AN backed by empirical evidence that providers may implement in practice.

Comparing changes in eating disorder psychopathology and comorbid symptoms over treatment in anorexia nervosa and atypical anorexia nervosa in a partial hospitalization program.

OBJECTIVE: The objective of this study is to compare treatment trajectories in anorexia nervosa (AN) and atypical AN. METHOD: Adolescents and adults with AN (n = 319) or atypical AN (n = 67) in a partial hospitalization program (PHP) completed diagnostic interviews and self-report questionnaires measuring eating disorder (ED), depression, and anxiety symptoms throughout treatment. RESULTS: Premorbid weight loss did not differ between diagnoses. Individuals with atypical AN had more comorbid diagnoses, but groups did not differ on specific diagnoses. ED psychopathology and comorbid symptoms of depression/anxiety did not differ at admission between groups nor did rate of change in ED psychopathology and comorbid symptoms of depression/anxiety from admission to 1-month. From admission to discharge, individuals with atypical AN had a faster reduction in ED psychopathology and comorbid symptoms of depression and anxiety (ps < 0.05; rs = 0.01-0.32); however, there were no group differences in ED psychopathology or depression symptoms at discharge (ps>.50; ds = .01-.30). Individuals with atypical AN had lower anxiety at discharge compared to individuals with AN (p = 0.05; d = .4). Length of stay did not differ between groups (p = 0.11; d = .21). DISCUSSION: Groups had similar ED treatment trajectories, suggesting more similarities than differences. PHP may also be effective for AAN. PUBLIC SIGNIFICANCE: This study supports previous research that individuals with AN and atypical AN have more similarities than differences. Results from this study indicate that individuals with AN and atypical AN have similar treatment outcomes for both ED psychopathology and depressive symptoms; however, individuals with atypical AN have lower anxiety symptoms at discharge compared to individuals with AN. AN and atypical AN also have more symptom similarity at admission and throughout treatment, which challenges their current designation as distinct disorders.

Differentiating anorexia nervosa and atypical anorexia nervosa with absolute weight cut-offs results in a skewed distribution for premorbid weight among youth.

OBJECTIVE: Anorexia nervosa (AN) and atypical AN are conceptualized as distinct illnesses, despite similar characteristics and sequelae. Whereas DSM-5 differentiates youth with AN and atypical AN by the presence of clinical 'underweight' (i.e., 5th BMI percentile for age-and-sex (BMI%)), we hypothesized that using this weight cut-off to discern diagnoses creates a skewed distribution for premorbid weight. METHOD: Participants included hospitalized youth with AN (n = 165, 43.1%) and atypical AN (n = 218, 56.9%). Frequency analyses and chi-square tests assessed the distribution of premorbid BMI z-scores (BMIz) for diagnosis. Non-parametric Spearman correlations and Stepwise Linear regressions examined relationships between premorbid BMIz, admission BMIz, and weight loss in kg. RESULTS: Premorbid BMIz distributions differed significantly for diagnosis (p < .001), with an underrepresentation of 'overweight/obesity' (i.e., BMI% ≥ 85th) in AN. Despite commensurate weight loss in AN and atypical AN, patients with premorbid 'overweight/obesity' were 8.31 times more likely to have atypical AN than patients with premorbid BMI% < 85th. Premorbid BMIz explained 57% and 39% of the variance in admission BMIz and weight loss, respectively. DISCUSSION: Findings support a homogenous model of AN and atypical AN, with weight loss predicted by premorbid BMI in both illnesses. Accordingly, premorbid BMI and weight loss (versus presenting BMI) may better denote the presence of an AN-like phenotype across the weight spectrum. Findings also suggest that differentiating diagnoses with BMI% < 5th requires that youth with higher BMIs lose disproportionately more weight for an AN diagnosis. This is problematic given unique treatment barriers experienced in atypical AN. PUBLIC SIGNIFICANCE: Anorexia nervosa (AN) and atypical AN are considered distinct conditions in youth, with differential diagnosis hinging upon a presenting weight status of 'underweight' (i.e., BMI percentile for age-and-sex (BMI%) < 5th). In our study, youth with premorbid 'overweight/obesity' (BMI% ≥ 85th) disproportionately remained above this threshold, despite similar weight loss. Coupled with prior evidence for commensurate characteristics and sequelae in both diagnoses, we propose that DSM-5 differentiation of AN and atypical AN inadvertently reinforces weight stigma and may contribute to treatment disparities in atypical AN.

Emotion coaching skills as an augmentation to family-based therapy for adolescents with anorexia nervosa: A pilot effectiveness study with families with high expressed emotion.

OBJECTIVE: To examine the feasibility and acceptability of augmenting family-based treatment (FBT) for adolescents with anorexia nervosa (AN) or atypical anorexia nervosa (AAN) with a parent emotion coaching intervention (EC) focused on reducing parent expressed emotion. METHOD: In this pilot effectiveness trial, families of adolescents with AN/AAN exhibiting high expressed emotion received standard FBT with either (1) EC group or (2) support group (an attention control condition focused on psychoeducation). RESULTS: Forty-one adolescents with AN or AAN were recruited (88% female, Mage = 14.9 ± 1.6 years, 95% White: Non-Hispanic, 1% White: Hispanic, 1% Bi-racial: Asian). Most study adolescents were diagnosed with AN (59%) while 41% were diagnosed with AAN. Participating parents were predominantly mothers (95%). Recruitment and retention rates were moderately high (76% and 71%, respectively). High acceptability and feasibility ratings were obtained from parents and interventionists with 100% reporting the EC intervention was "beneficial"-"very beneficial." The FBT + EC group demonstrated higher parental warmth scores at post-treatment compared to the control group (standardized effect size difference, d = 1.58), which was maintained at 3-month follow-up. Finally, at post-treatment, the FBT + EC group demonstrated higher rates of full remission from AN/AAN (40%) compared to FBT + support (27%), and were nine times more likely to be weight restored by 3-month follow-up. DISCUSSION: Augmenting FBT with emotion coaching for parents with high expressed emotion is acceptable, feasible, and demonstrates preliminary effectiveness. PUBLIC SIGNIFICANCE: Family based treatment for AN/AAN is the recommended treatment for youth but families with high criticism/low warmth are less likely to respond to this treatment. Adding a parent emotion coaching group (EC) where parents learn to talk to their adolescents about tough emotions is feasible and well-liked by families.

An examination of adults with atypical anorexia nervosa at admission to treatment at higher levels of care: An attempt to increase diagnostic clarity.

OBJECTIVE: Anorexia nervosa (AN) is a serious illness with a high mortality rate and multiple physiological complications. The vague definition of atypical AN allows for subjective interpretation. This retrospective study aimed to focus future research on the operational definition of atypical AN by examining four factors associated with atypical AN at admission to higher level of care treatment. METHODS: Adults with atypical AN (n = 69) were examined within sample analyses among four groups: (1) >10% versus ≤10% weight loss; (2) weight loss within the previous 3 months versus >3 months; (3) engaging in purging behaviors versus absence of purging behaviors; and (4) endorsing versus not endorsing significant cognitive aspects of AN. RESULTS: Patients with atypical AN endorsed elevated ED cognitions on the Eating Disorder Examination-Questionnaire and depressive symptoms; a lack of association was found between weight loss severity and weight loss time frame with depressive symptoms, eating concern, and restraint. Purging behavior was associated with a higher expected body weight percentage (%EBW) and dietary restraint, while greater AN cognitions were associated with a higher EBW and weight loss percentage. Few patients demonstrated bradycardia, hypophosphatemia, or amenorrhea. DISCUSSION: This study demonstrated the severity of ED cognitions and depressive symptoms in this atypical AN sample and provided directions for future studies in the nosology of atypical AN. It may be important to distinguish between individuals with atypical AN who are purging and those who are not. Atypical AN was associated with a low frequency of physiological disturbances. PUBLIC SIGNIFICANCE: This study provides further clarification regarding the operational definition of atypical AN; currently, a constellation of symptoms under Other Specified Feeding or Eating Disorders. This study was consistent with previous research in reporting severe eating disorder cognitions in adults with atypical AN, and noted the potential importance of distinguishing a purging distinction. A minority of patients in this study had physiological impairments.

Associations between low body weight, weight loss, and medical instability in adults with eating disorders.

OBJECTIVE: The physical complications of atypical anorexia nervosa remain understudied, with most studies completed in adolescents. This study seeks to examine the impact of various weight measures as predictors of medical instability in a large cohort of adult eating disorder patients. METHODS: In this retrospective cohort study, the impact of admission body mass index (BMI), weight suppression, and recent weight loss (the rate of weight loss within the last 12 months) toward the development of medical complications of malnutrition were examined. Multivariable logistic regression assessed the association of binary clinical outcomes of interest with recent weight loss and weight suppression (adjusting for age, admission BMI, gender, and purging behaviors). Odds ratios (OR) and 99% confidence intervals were reported. RESULTS: Greater recent weight loss increased the odds of developing low prealbumin and reduced hand grip strength. A greater weight suppression was associated with increased likelihood of amenorrhea, reduced systolic blood pressure, nadir hemoglobin, and weekly weight gain upon nutritional rehabilitation. Lower admission BMI was predictive of all the medical outcomes examined, with the exception of bradycardia, and was generally the strongest predictor based on standardized coefficients. DISCUSSION: Recent weight loss and weight suppression are predictive of some of the physiologic changes of malnutrition, although low BMI is seemingly the greatest predictor for the development of these complications. These findings suggest that some patients with aggressive weight suppression and/or acute weight loss would benefit from medical stabilization, although this needs to be further defined. PUBLIC SIGNIFICANCE: In adults, low BMI seems to be a better predictor of medical complications than weight suppression or aggressive recent weight loss. In adults, greater weight suppression is associated with increased likelihood of amenorrhea, reduced systolic blood pressure, nadir hemoglobin, and weight gain upon nutritional rehabilitation.

The role of readiness and confidence to change in the treatment of atypical anorexia nervosa and bulimia nervosa.

OBJECTIVE: Atypical anorexia nervosa (AN) is a serious eating disorder that is more common in the population than AN. Despite this, people with atypical AN are less likely to be referred or admitted for eating disorder treatment and there is evidence that they are less likely to complete or benefit from existing interventions. This study examined whether baseline readiness and/or confidence moderated outcomes from 10-session cognitive behavioral therapy among people with atypical AN and bulimia nervosa (BN), and whether the impact of these variables differed between diagnoses. METHODS: Participants (n = 67; 33 with atypical AN) were a subset from an outpatient treatment study. Linear mixed model analyses were conducted to examine whether baseline readiness and/or confidence moderated outcomes. RESULTS: People with BN who had higher levels of readiness or confidence at baseline had steeper decreases in eating disorder psychopathology over time. There was no evidence that readiness or confidence moderated outcomes for people with atypical AN. DISCUSSION: This study suggests that the moderators that have been identified for other eating disorders may not apply for people with atypical AN and highlights a need for future work to routinely investigate whether theoretically or empirically driven variables moderate outcomes in this little-understood population. PUBLIC SIGNIFICANCE STATEMENT: People with bulimia nervosa with higher readiness and confidence experienced greater decreases in eating disorder symptoms than people with lower readiness and confidence when treated with cognitive behavioral therapy. These findings did not apply to people with atypical anorexia nervosa. Results demonstrate that future work is urgently required to identify helpful treatments for people with atypical anorexia nervosa as well as the variables that have a positive impact on outcomes in treatment for these individuals.