Many studies have shown that experiencing chronic racial discrimination chips away at the mental health of African-Americans. But a new Cornell study sheds light on precisely how -- and to what effect -- chronic racial discrimination erodes mental health.

The study found blacks may, in general, have poorer mental health as a result of two mechanisms: First, chronic exposure to racial discrimination leads to more experiences of daily discrimination and, second, it also results in an accumulation of daily negative events across various domains of life, from family and friends to health and finances. The combination of these mechanisms, reports Anthony Ong, assistant professor of human development in the College of Human Ecology at Cornell, places blacks at greater risk for daily symptoms of depression, anxiety and negative moods.

"As a result, African-Americans experience high levels of chronic stress. And individuals who are exposed to more daily stress end up having fewer resources to cope with them," said Ong.

The study, one of the first to look at the underlying mechanisms through which racial discrimination operates to affect the daily mental health of African-Americans, was conducted with Cornell graduate student Thomas Fuller-Rowell and Anthony Burrow, assistant professor of psychology at Loyola University-Chicago; it is published in the June issue of the Journal of Personality and Social Psychology (96:6).

The researchers examined the ways that chronic discrimination exerts a direct influence on daily mental health and an indirect influence through daily stress (i.e., daily racial discrimination and negative events) by analyzing daily questionnaires from 174 African-Americans for 14 days. Participants answered questions daily about the frequency of racially stressful encounters, mental health symptoms, mood and stressors across life domains.

"What we found was that it is the daily discrimination and daily stress that are driving the psychological distress," Ong said.

The authors noted that racial discrimination in this country "is a ubiquitous experience in the lives of African-Americans," citing various studies that reported that between half to three-quarters of black respondents report experiencing racial discrimination. They also cite a 2003 review of 32 studies that found a positive link between perceptions of racial discrimination and mental illness in all but one of the studies.

Based on the new study, Ong emphasized that the tendency for serious stressors, such as racial discrimination, to expand and generate additional stressors -- a process called stress proliferation -- requires that interventions cast a wide net.

"It is not enough that interventions target one problem," Ong noted, "even if it appears to be a serious stressor, when there might be multiple hardships and demands that are instrumental in structuring people's daily lives. Chronic exposure to racial discrimination provides a poignant illustration of the proliferation of stress stemming from repeated discriminatory experiences."