Early research by Julian Leff at the Institute of Psychiatry and David Goldberg at UCLA on schizophrenia focused on the role of “expressed emotion” in families. They coined this term to essentially describe a negative and critical communication style that appeared to characterize many of the families who had members suffering from schizophrenia.
The results from their early studies were indeed impressive. Patients who lived with family members who were overly critical of them and had a negative communication style relapsed more often and quicker.
These results have been replicated across almost all major mental disorders (except one)*, and of course bipolar disorder. Patients with bipolar disorder actually have the highest sensitivity levels to expressed emotion/criticism.