Expressed emotion is a measure of the amount of negative emotion displayed in the family or caregivers of people with a mental-health problem. It is made up of hostility - blaming the sufferer for their illness - overinvolvement (family members blaming themselves for the sufferer's illness), and criticism. High levels of expressed emotion are linked to poorer outcomes in people with bipolar disorder, and in particular worse depression. Criticism and hostility are known to particularly affect people with bipolar disorder and researchers from the University of Miami looked into why these people might be particularly vulnerable to criticism. In a carefully-controlled experiment they subjected 70 participants - 35 of whom had bipolar disorder - to criticism and monitored how they reacted. (The participants were told that the criticism was part of the experiment after it was over). The researchers found that although the people with bipolar disorder reacted more negatively to criticism they recovered as quickly as the unaffected control group. Being female, perceiving the criticism as more negative, being disabled and having fewer positive relationships all made the participants with bipolar disorder more reactive to criticism.
Cuellar, Amy K., Johnson, Sheri L. and Ruggero, Camilo J. - Affective reactivity in response to criticism in remitted bipolar disorder: a laboratory analog of expressed emotion Journal of Clinical Psychology September 2009, 65(9), 925-941