What is different about anorexia nervosa sufferers that, in contrast to most dieters, enables them to maintain a persistent calorie deficit? Although no one can truthfully claim they know the full answer to that question, we do know that part of the answer most likely lies with serotonin (5-HT), a molecule that neurons use to communicate with each other.
I’ve written about serotonin in the context of anorexia nervosa before, so I’ll just do a brief summary of the important points here:
Given that serotonin mediates a lot of psychological and physiological traits associated with anorexia nervosa, and given that altering food intake affects how much serotonin is made in our bodies, it is no surprise that it has been a popular research target among eating disorder researchers.
Two important findings that are particularly relevant to the study I will discuss below are:
These findings suggest that individuals with AN may have premorbid (or intrinsic) abnormalities in the serotonergic system (elevated 5-HT activity compared to healthy controls), which may mediate behavioural and/or temperamental traits that in turn predispose these …
Excessive exercise played a big role in my eating disorder and, predictably, I am drawn to studies that look at the role excessive exercise plays in eating disorder symptomatology, course and outcome. This topic has captured the interest of many eating disorder researchers, with studies revealing that up to 80% of individuals with anorexia nervosa may exercise excessively (Davis et al., 1997), though others suggest more modest statistics, around 39% (Shroff et al., 2006; Tetyana wrote a post about this article here).
Scholars have also noted the potentially obsessive and compulsive nature of exercise among some individuals with eating disorders and have made the natural transition toward examining whether links exist between excessive exercise and obsessive-compulsive disorder (OCD) and/or obsessive-compulsive personality disorder (OCPD) traits (If you are confused about the difference between OCD and OCPD, click here). Young, Rhode, Touyz & Hay (2013) conducted a rigorous systematic review to synthesize and draw conclusions from the results of such studies.
The authors aimed to clarify the links between both OCPD traits and OCD …
Anxiety disorders (ADs) are common among patients with eating disorders. In one study of female inpatients, around 50-65% had a comorbid anxiety disorder (see my post here). Anxiety disorders in patients with anorexia nervosa (AN) typically begin before the eating disorder and often persist after weight restoration and recovery (Bulik et al., 1997; Casper, 1990). Moreover, previous twin studies have suggested that there’s a “correlation between eating disorders and certain anxiety and depressive disorders, suggesting they comprise a spectrum of inherited phenotypes” (Hudson et al., 2003; Mangweth et al., 2003).
In this paper, Michael Strober and colleagues hypothesized that anxiety disorders and anorexia nervosa share common genetic, neural, and/or behavioural mechanisms. As such, they sought to investigate the association of AN with ADs by studying the prevalence of ADs in first-degree relatives of AN patients and comparing it to the prevalence of ADs in first-degree relatives of healthy controls.
Their rationale was that,
Just to note, this study only investigated the relatives of restrictive-type AN patients, and in addition to ADs, they included obsessive compulsive personality disorder (OCPD) …
Excessive exercise (EE) is common among eating disorder patients. Indeed, in the study I’ll write about today, 39% of patients engaged in EE. Previous studies have tried to find psychopathological and personality correlates of EE but the results have been inconsistent. Some studies have suggested that impulsivity and addictiveness are highly correlated with EE whereas others found that anxious and depressive traits were more closely associated.
In this multi-site study, Shroff and colleagues wanted to examine the prevalence of EE across eating disorder subtypes and the personality traits and clinical variables that were associated with EE in a large sample of women (1,857 in this study).
But first, what exactly is “excessive exercise”?
In this study, participants were deemed to be excessive exercisers when they endorsed at least one of the following with regard to exercise: “(1) severe interference with important activities; (2) exercising more than 3 h/day and distress if unable to exercise; (3) frequent exercise at inappropriate times and places and little or no attempt to suppress the behavior; and (4) exercising despite more serious injury, illness or medical complication.”
PREVALENCE OF EXCESSIVE EXERCISE ACROSS ED …
This post continues the discussion of the chapter on eating disorders by Carolina Lopez, Marion Roberts, and Janet Treasure from The Handbook of Neuropsychiatric Biomarkers, Endophenotypes and Genes (2009). Part 1 focused on neurotransmitter biomarkers, and this second part will focus on the neuropsychological biomarkers.
Attentional bias is the tendency for individuals to attend to or be distracted by emotionally relevant stimuli over neutral stimuli. Attentional biases have been observed in several studies:
These biases can be minimal but annoying: waiting in line at the pharmacy, staring into space and finding your focus automatically pulled to the magazine headlines promising diet tips or drop a dress size in a week! even if those topics would not normally interest you. Or they might have a more intrusive …
Symptom fluctuation and diagnostic crossover are common in eating disorder patients. A study by Eddy et al. (2008) - who followed patients over an average of 7 years – showed that crossover between subtypes and full-syndrome diagnoses is very common : of those initially diagnosed with anorexia nervosa, almost 73% crossed over to another diagnosis (between symptoms and to bulimia nervosa). More specifically, roughly 50% experienced fluctuation between subtypes (restricting, AN-R, and binge/purge type, AN-BP) and roughly 35% crossed over to bulimia nervosa (a subset experienced both). Of those initially diagnosed with bulimia, roughly 14% crossed over to AN-BP and of those, 3.91% crossed over to AN-R.
This finding (though, well-known to ED specialists and even more well-known to patients) has important implications for treatment. For example, CBT and anti-depressants seem to have positive results in bulimic patients, but not so much in anorexics. What then, about those that crossover from AN-R/AN-BP to BN? Would they, too, benefit from these interventions?
In order to answer those questions, it would be helpful to know who whether we can actually predict who …