Tuesday, July 17, 2007

"I'm Not As Slim As That Girl"


Fig. 1 (Friederich et al., 2007). Subjective anxiety ratings in response to images of interior design and body shape images (n = 16 healthy women). 0 = not anxious at all, 10 = very anxious. [NOTE: different results may be obtained in avid fans of Martha Stewart Living or HGTV or Queer Eye for the Straight Guy.]

The incidence of body dissatisfaction is notoriously high among women in western industrial society, and the constant stream of skinny skinny celebrities appearing in the media influences self-esteem. A meta-analysis of 25 published studies (Groesz et al, 2002) revealed that
Body image was significantly more negative after viewing thin media images than after viewing images of either average size models, plus size models, or inanimate objects. ... Results support the sociocultural perspective that mass media promulgate a slender ideal that elicits body dissatisfaction. Implications for prevention and research on social comparison processes are considered.
A recent neuroimaging study (Friederich et al., 2007) evaluated the brain activity of non-eating disordered1 women as they viewed photographs of slim models and stylish interior designs. The stimuli were
Images of slim female bodies and interior design were provided by a women’s magazine. The images were selected from a larger database in a pilot study, if they were rated by 38 healthy female volunteers as (1) easy to recognize, (2) interesting and (3) provoking anxiety in self-comparison. ... The body shape images of fashion models depicted either the whole or part of the body (head excluded) of slim women dressed in clothes that revealed their shape (e.g., bikinis or body fitting sports clothing). The comparison (control) images were of interior designs (inanimate objects only, e.g., rooms containing designer cupboards, drawers, curtains, lights).
One weakness in the experimental design is that images of "average-sized" female bodies (or plus size models) were not included. This would seem to be an obvious comparison, as it would control for the appearance of bodies yet provoke lower anxiety ratings (in fact, one could run a pilot study to match the interior designs and everyday bodies on anxiety ratings).

A procedural aspect that was well-controlled was the task for each condition: compare one's own body/house to the ones in the pictures. Seems that comparing one's tiny apartment to Architectural Digest displays might induce greater anxiety in some individuals not included in the current study (the "Martha Stewart effect").

Nonetheless, results indicated that
Anxiety ratings in response to body models were positively correlated with activation in the left amygdala, bilateral basal ganglia (left putamen, left caudate body, right globus pallidus, right claustrum), bilateral dorsal anterior cingulate (maximum response in BA 32), left ventrolateral PFC (maximum response in BA 47), left apical PFC (maximum response in BA 10), right dorsolateral PFC (maximum response in BA 8), right precentral cortex (maximum response in BA 6) and left lingual gyrus (maximum response in BA 19).
Some of these brain regions are associated with responses to fear and anxiety (e.g., amygdala, portions of the basal ganglia). In addition, scores on the Eating Disorder Examination Questionnaire (global score, shape concern, and weight concern measures) correlated with anxiety ratings. The authors noted that dissatisfaction with one's body is not limited to eating disordered (ED) populations, and suggested that ED prevention programs could incorporate training in the top-down control of emotional responses [perhaps indexed by PFC and ACC activity here] when comparing one's self to an overly thin model.


Footnote

1 For inclusion in the study, the participants had to have a body mass index between 17.5 and 25.0 kg/m2. The former value is right at the cutoff for anorexia. However, the mean BMI was a healthy 21.9, and the 16 participants had never received diagnoses of an eating disorder or other psychiatric illnesses.


References

Friederich HC, Uher R, Brooks S, Giampietro V, Brammer M, Williams SC, Herzog W, Treasure J, Campbell IC. (2007). I'm not as slim as that girl: Neural bases of body shape self-comparison to media images. Neuroimage Jun 2; [Epub ahead of print].

The aim of the present study was to assess the impact of images of slim female fashion models on healthy young women. Brain responses to images of slim-idealized bodies (active condition) and interior designs (control condition) were measured using functional neuroimaging in 18 healthy young women. Instructions encouraged the participants to compare their own body shape/own home with the one in the images. Participants rated the level of anxiety that they experienced while exposed to the images. In the active relative to the control condition, participants activated body shape processing networks, including the lateral fusiform gyrus on both sides, the right inferior parietal lobule, the right lateral prefrontal cortex and the left anterior cingulate. The level of reported anxiety during the exposure to slim bodies correlated with established measures of shape and weight concern and with brain activations in bilateral basal ganglia, left amygdala, bilateral dorsal anterior cingulate, and left inferior lateral prefrontal cortex. Brain networks associated with anxiety induced by self-comparison to slim images may be involved in the genesis of body dissatisfaction and hence with vulnerability to eating disorders.


Groesz LM, Levine MP, Murnen SK (2002). The effect of experimental presentation of thin media images on body satisfaction: a meta-analytic review. Int J Eat Disord 31:1–16.

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