The recent revision of the American Psychiatric Associations Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition (DSM-5) altered several eating disorder diagnostic criteria.

Some have expressed concern that these revisions are overly broad and may result in over diagnosis in some clinical populations. One clinical population where this is a concern is obesity.

A research study has been recently published addressing this issue.

Jennifer Thomas and colleagues at Harvard University and Massachusetts General Hospital recruited a series of subjects from an obesity program for eating disorder diagnostic assessment.

All subjects completed an assessment for presence of an eating disorder 
diagnosis using both DSM-IV and DSM-5 criteria.

For DSM-IV eating disorder diagnoses, the research team used a validated module from a validated measure known as SCID-IV. For DSM-5 eating disorder diagnosis an early structured interview developed by the DSM-5 Eating Disorders Task Group was used.

The key findings from the study included:

• Prevalence rates for eating disorders using DSM-5 criteria did not increase compared to DSM-IV criteria
• Bulimia nervosa prevalence rates were 2% in both interviews
• Binge eating disorder prevalence rates were 9% in both interviews
• An additional 20% of the obese sample met residual eating disorder criteria in both interviews

Obese individuals with a formal eating disorder diagnosis endorsed higher rates of psychological impairment, depression and anxiety validating the impact of eating disorder comorbidity.

Assessment for the presence of eating disorders is an important part of treatment planning. Eating disorders are more prevalent in obese populations are relatively easy to diagnose.

Some studies have found poor outcomes in obese populations with severe binge eating behaviors.

Treatment of a comorbid eating disorder in obese populations may improve weight and psychological outcomes.

Readers with more interest in this research can access the free full-text manuscript by clicking on the PMID link below.

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Thomas JJ, Koh KA, Eddy KT, Hartmann AS, Murray HB, Gorman MJ, Sogg S, & Becker AE (2014). Do DSM-5 eating disorder criteria overpathologize normative eating patterns among individuals with obesity? Journal of obesity, 2014 PMID: 25057413

There is increasing evidence for inflammation contributing to risk for a variety of psychiatric disorders.

I previously summarized research supporting use of anti-inflammatory drugs in the treatment of depression.

A recent study from Finland supports an inflammation link to the eating disorder categories.

The key elements of the design of this study included:

• Subjects: 2342 subjects admitted for treatment in the Eating Disorders Unit at the central hospital in Finland. Four controls were identified for each case matched by age, gender and place of residence
• Identification of presence for autoimmune diseases: Cases and controls were examined for the presence of one of 30 autoimmune diagnoses in their Hospital Discharge Register
• Statistical analysis: Period and lifetime rates for autoimmune disorders were compared between eating disorder cases and control using logistic regression modeling with calculation of odds ratios and 95% confidence intervals.

Here are the important findings from the study:

• Eating disorders subjects had a 5.6% rate for presence of any autoimmune disease compared to only 2.8% of controls (Odds ratio 2.13, 95% confidence interval 1.71-2.65)
• Rates for autoimmune disorders were increased across all eating disorder diagnostic categories including anorexia nervosa, bulimia nervosa and binge eating disorder
• Within autoimmune disease subtypes, endocrinological and gastroenterological diseases were statistically increased in eating disorders
• Type I diabetes and Crohn's disease were individual autoimmune disorders found at higher rates in eating disorders

The authors note there are several methods that could explain the association between autoimmunity and eating disorder risk. Higher rates of autoantibodies against peptides that control appetite and stress response could contribute to eating disorder risk.

Additionally, the authors note disturbed eating may contribute to disturbance of the microbiome of the gut. Gut microbiome is a known regulator of autoimmunity and a contributor to allergies and type I diabetes risk.

The authors noted additional specific autoimmune disorders may be increased in eating disorders but due to small sample size their study may have not found a statistical association.

Systemic lupus erythematosis rates were increased in the eating disorder group but this was one of the individual disorders that failed to reach statistical significance.

The take home message for clinicians treating eating disorder patients is to be vigilant for the presence of autoimmune medical disorders in this population. Accurate and early detection of autoimmune disorders in those with eating disorders may contribute to improved medical outcomes.

Readers with more interest can access the free full text manuscript by clicking on the PMID link below.

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Raevuori A, Haukka J, Vaarala O, Suvisaari JM, Gissler M, Grainger M, Linna MS, & Suokas JT (2014). The increased risk for autoimmune diseases in patients with eating disorders. PloS one, 9 (8) PMID: 25147950

I am focusing on recent research in eating disorders this month on Brain Posts.

Here are some of the research abstracts I will be reviewing for upcoming posts.

Clicking on the title will take you to the PubMed abstract and also to a link for the free full-text manuscript.

Higher parental education as a risk factor for eating disorders
This study of the Swedish population examined the effect education and social class on risk for eating disorders. Individuals diagnosed with an eating disorder were more likely to have higher educational levels in their parents. This is an interesting finding as educational typically reduces rates for many psychiatric disorders. 

Increased rates of autoimmune diseases in patients with eating disorders
A study of a large cohort from Finland found higher rates of a variety of autoimmune disorders in a sample of patients treated for eating disorders. Type I diabetes and Crohn's disease were two of the disorders that were more likely to be seen in eating disorder patients compared to controls.

Epidemiology of eating disorders
This literature examined 149 studies on the epidemiology of eating disorders. The review found evidence for genetic and environmental factors as risk factors for eating disorders. Additionally, the review found support for esthetic or weight-oriented sport participation also as risk factors for eating disorders.

Evidence for effective treatment options of eating disorders in young people
This review examined evidence for effective prevention and treatment of eating disorders in adolescents and young adults. The authors note the paucity of large well-designed clinical trials for the treatment of most eating disorders and make recommendations about directions for future research. 

Inferior frontal cortex network abnormalities in anorexia nervosa
This study examined resting functional connectivity in 12 subjects with anorexia nervosa compared to controls. The study found impairment in connectivity in the inferior frontal cortex in those with anorexia nervosa.

Binge eating and risk for gastrointestinal disorders
The Swedish Twin Study of Adults: Genes and Environment (STAGE) cohort was used to look for associations between binge eating and gastrointestinal disorders. Binge eating was found to be increased in irritable bowel syndrome and may be important in effectively managing this disorder. 

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