Faculty Bibliography

OBJECTIVE: This study sought to quantify, among patients hospitalized for the treatment of anorexia nervosa (AN), the reinforcing value of exercise, defined as the amount of work a patient would expend for the opportunity to exercise. METHOD: Sixteen inpatients with AN performed a computerized progressive ratio (PR) task for the opportunity to exercise for either 15 or 30 min, or a monetary voucher. Exercise "breakpoint" was calculated and compared with clinical measures. RESULTS: Patients performed an average of 1134.4 (+/-751.2) button presses for exercise. Exercise breakpoint was significantly correlated with the Beck Depression Inventory (BDI; r = .728, p = .001), and there was a trend toward a correlation with the Commitment to Exercise Scale (CES; Davis, 1993; r = .490, p = .054). CONCLUSION: Results support the feasibility and potential utility of this novel application of the PR task to quantify the reinforcing value of exercise in AN. The association between exercise and depression is consistent with some prior studies in AN. The trend toward an association with CES scores suggests that breakpoint captures an aspect of the motivation for exercise in this population.

Elevated physical activity is commonly observed among patients with Anorexia Nervosa (AN) and can manifest in several forms. While elevated physical activity may play a key role in the pathophysiology of this disorder, much remains unknown about it, including the relationship among its various manifestations, and their underlying mechanism(s). The purposes of the current study were to (1) quantify locomotor activity in inpatients with AN using an accelerometer, (2) determine the association between locomotor activity and exercise history and (3) determine the association between urinary cortisol and physical activity. Thirty-six women hospitalized with AN wore activity armbands for 48 h during the first 2 weeks of hospitalization, collected 24-h urine to measure cortisol, and completed rating forms. Activity counts varied more than four-fold among individuals but were consistent within individuals over the 2 monitoring days (p<0.001). Averaged 24-h activity counts were positively correlated with pre-hospitalization attitude towards exercise as measured by the Commitment to Exercise Scale (CES; p=0.032). Forty-two percent of women reported "high" exercise in the 3 months before hospitalization; compared to non-high-exercising patients, these women demonstrated a higher CES score (p<0.001) and a trend toward greater activity counts (p=0.059). Urinary cortisol was positively associated with activity counts (p=0.044) and CES score (p=0.018). These data suggest that some women with AN have a higher "drive" for physical activity that persists into early hospitalization. HPA axis abnormalities may be associated with this state.

Women with eating disorders report using large quantities of artificially sweetened products, but this has not been quantified. OBJECTIVE: The authors assessed the use of selected artificially sweetened low-calorie products among women with eating disorders compared with controls. METHOD: Thirty women with anorexia nervosa (18 with the restricting subtype [AN-R] and 12 with the binge/purge subtype [AN-B/P]), 48 women with bulimia nervosa (BN), and 32 healthy control women completed a survey of frequency and amount of consumption of chewing gum, artificially sweetened low-calorie beverages, and packets of artificial sweetener in the previous month. RESULTS: A greater proportion of women with AN-B/P and BN reported use of each product, compared with women with AN-R and control participants. Among product users, patients with eating disorders reported using greater amounts than controls. Among patients who reported binge eating and/or purging, the quantity of each product used was inversely correlated with body mass index (BMI). CONCLUSION: These data suggest an increased drive for sweet orosensory stimulation in women with AN and BN.

Although sweet solids and liquids are palatable to humans and ingested frequently when readily available, the quantitative relationship between sweet taste and intake has not been reported in humans. To investigate the quantitative relationship between sweet taste and intake directly, we adapted the modified sham feeding technique, previously used in humans for the study of the orosensory control of autonomic, neuroendocrine, and metabolic mechanisms, to measure the intake of solutions both unsweetened and sweetened with four concentrations of sucrose. By limiting the sucrose stimuli to the mouth, the modified sham feeding technique measures the orosensory stimulation of intake by sucrose in the absence of inhibitory postingestive stimulation. Nine healthy women were randomly presented with two series of five solutions of cherry Kool Aid unsweetened or sweetened with one of four concentrations of sucrose (2.5%, 5%, 10%, or 20%) in a closed opaque container fitted with a straw. They were instructed to sip as much as they wanted of the liquid during 2-min trials and to spit the fluid out into another opaque container. At the end of each trial, they used Visual Analogue Scales to rate the perceived intensities of sweetness and liking of the liquid that they had just sipped and spit. Intake, liking and perceived sweetness were significantly affected by sucrose concentration (p values