448 CHAPTER 10
problematic by nature, or is there, in fact, a faulty chemical pathway in your brain?
If so, was it there before you started starving yourself, or did the starving put it there?...
All of the above?
(1998, pp. 195–196)
In this passage, Hornbacher is trying to understand how, or why, some people—but
not others—develop an eating disorder. Note that she mentions explanations that
involve all three of the types of factors in the neuropsychosocial approach, although
she does not consider ways in which such factors might interact. Given that up to
half of the people with one of the eating disorders (anorexia, bulimia, or EDNOS)
have had or will have another of these disorders, it makes sense to examine the etiol-
ogy of these disorders collectively, rather than individually.
People with an eating disorder generally do not come to the attention of re-
searchers until after they’ve developed the disorder. Yet once the eating disorder has
developed, it is diffi cult to disentangle causal factors from factors that refl ect the
altered eating habits and poor nutrition that predated the full-blown disorder. In
other words, it is challenging for researchers to distinguish the causes of eating dis-
orders from the widespread effects of eating disorders on neurological (and, more
generally, biological), psychological, and social functioning.
This diffi culty in untangling cause and effect means that researchers do not know
which of the neuropsychosocial factors that are associated with eating disorders
actually give rise to the disorders. All that can be said at this time is that a num-
ber of factors are associated with the emergence and maintenance of eating disorders
(Dolan-Sewall & Insel, 2005; Jacobi et al., 2004; Streigel-Moore & Cachelin, 2001).
An additional challenge to researchers is the high rate of comorbidity of other
psychological and medical disorders with eating disorders, which makes it diffi -
cult to determine the degree to which risk factors uniquely lead to eating disorders,
rather than being associated more generally with the comorbid disorders (Jacobi
et al., 2004; Johnson, Cohen, Kasen et al., 2002).Neurological Factors: Setting the Stage
We’ve already noted that the excessive caloric restriction in anorexia leads to spe-
cifi c medical effects, notably changes in hormones, metabolism, and body function-
ing. The eating changes and purging involved in bulimia (and anorexia, if purging
occurs) bring their own medical effects and biological changes. Researchers try to
determine whether neurological (or other biological) abnormalities they fi nd among
people with an eating disorder might have caused the disorder, might be caused
by the disorder, or are simply correlated with the disorder (Franko et al., 2004;
Jacobi et al., 2004).Brain Systems
Neuroimaging studies have revealed many differences between the brains of people
with eating disorders and those of control participants (Frank et al., 2004; Kaye,
Frank, et al., 2005; Takano et al., 2001). Most notably, people who have anorexia
have unusually low activity in several key areas of the brain: (1) the frontal lobes,
which are involved in inhibiting responses and in regulating behavior more generally
(a defi cit in such processing may contribute to eating too much or eating too little);
(2) the portions of the temporal lobes that include the amygdala, which is involved in
fear and other strong emotions (fear helps prevent people from putting themselves in
danger, and dampening this emotion may contribute to eating disorders); (3) the pa-
rietal lobes, which may play a key role in representing body size; and (4) the anterior
(i.e., front) part of the cingulate cortex, which lies in the frontal lobes at the midline
of the brain and is involved in monitoring for confl icts among competing responses
or among competing information retrieved from memory (Kuhl et al., 2008); a defi cit
here may contribute to problems in learning to inhibit dysfunctional behavior.
Examining groups of patients can be useful, insofar as general patterns of brain
differences can help to identify key characteristics associated with a disorder. However,