Assessing affective variability in eating disorders: Affect spins less in anorexia nervosa of the restrictive type

• Patients with anorexia and bulimia nervosa show equal mean affect in daily life.
• Patients with anorexia nervosa-restrictive type show less affective lability.
• Affect spins less in patients with anorexia nervosa-restrictive type.
• Spin and pulse are two new concepts to quantify affective variability.
• Spin and pulse may reveal insights hidden with traditional assessment methods.

Differences in affective variability in eating disorders are examined using an ecological momentary assessment (EMA) protocol. It is hypothesized that restriction serves to pre-empt the activation of affect whereas bulimic behavior serves to cope with overwhelming affect once activated. Therefore, we expect anorexia nervosa (AN) patients of the restricting type (AN-RT) to have lower mean levels of affect and less affective variability than Bulimia Nervosa (BN) patients. Patients' successive affective states over time are represented as different positions in a two-dimensional space defined by the orthogonal dimensions of valence and activation. Affective variability is measured by the within person variance and the new concepts of pulse and spin. Results of this exploratory study suggest that the diagnostic groups have the same mean levels of affect but affect spins less in patients with AN-RT. Using an EMA protocol and measures like pulse and spin may reveal insights in eating disorders that remain hidden with more traditional assessment methods.