Objective

Eating disorder-related beliefs among individuals with anorexia nervosa (AN) often approach delusional intensity. Research to date on delusional beliefs in AN has been cross sectional. Thus, it is unknown how the intensity of delusional beliefs changes over time and if such change has prognostic value.

Method

We assessed 50 individuals with severe to extreme AN (≥18 years old; M [SD] body mass index =12.7[1.3] kg/m2) at an inpatient medical stabilization facility within 96 hr of admission; 35 (70%) also completed the assessment at discharge (M[SD] = 25.53[13.21] days). Participants completed the Brown Assessment of Beliefs Scale and a battery of self-report measures of eating disorder-related psychopathology.

Results

The admission-to-discharge decrease in delusional intensity was not significant (p = .592; Hedges g = .10). Tests of predictive effects indicated that higher delusional intensity at intake predicted higher fear of fatness and restrictive eating, two hallmark features of AN, but not BMI, body checking, feared food avoidance, eating disorder-related impairment, depression, binge eating, or purging behavior at discharge.

Discussion

Although the delusional intensity of eating disorder beliefs did not significantly improve over this relatively brief interval, delusional intensity may be associated with the severity of central eating disorder attitudes and behaviors. Delusional intensity may therefore be a negative prognostic indicator, possibly warranting further treatment. Future research should examine changes in delusional intensity over longer intervals and test whether specifically targeting delusional beliefs improves treatment outcomes among individuals with AN.