Dr. Lincoln is actively engaged in African American communities. She is founder and Chair of Advocates for African American Elders, an advocacy group comprised of community advocates and representatives from the Department of Mental Health, Pacific Clinics, Alzheimer's Association, AARP, and California Senior Leaders. Dr. Lincoln is a member of several associations, the recipient of many honors and also contributes to a blog where she fuses social commentary with her vast knowledge of health and mental health about African American communities; posing questions such as "Is Being Black Bad for Your Health?," addressing policy such as the Affordable Care Act and sharing her inspiration for a "Healthy Black America."
Donald Lloyd, PhD
Research Associate Professor
University of Southern California
School of Social Work
DONALD LLOYD, Research Associate Professor at USC School of Social Work, is a social epidemiologist with training in cultural anthropology and medical sociology. He has worked on several large-scale community-based studies in Canada and Florida. To date his work has been cited in 1045 refereed publications, with work on the epidemiology of social stress receiving the greatest attention. His recent work focuses on life course processes that are associated with differential risk for psychiatric illness and substance use disorders across sociodemographic groups. Dr. Lloyd's work in the Roybal Institute builds upon his research at the nexus of aging, disablement, and mental health.
Additional projects have addressed the role of lifetime cumulative exposure to major and potentially traumatic events in the risk for initial onset of major depression, post-traumatic stress disorder, alcohol dependence and drug dependence disorder. His published research documents the important distinction between proximal and distal exposure to stressful events and their independent contribution to the risk for subsequent disorder. His recent research examines trajectories of exposure to stressful events over the life course, including factors that affect the shape of the exposure profile and the health outcomes that are associated with distinct trajectories. Prior to joining the Trojan Family, Dr. Lloyd conducted a popular graduate seminar in life course epidemiology at Florida State.
Background for the pilot
African American women have the highest prevalence rate of obesity compared to any other racial or ethnic group in the United States. In 2007-2008, non-Hispanic Black adolescent girls (29.2%), women (49.6%) and older women (60 years and older) (61%) had the highest prevalence of obesity. Many researchers are now identifying obesity as the main factor driving racial disparities in health among women. It is estimated that if current trends persist, all Black women will be overweight or obese by 2034.
What are the consequences of obesity?
While obesity is a serious health issue by itself, it is also associated with a host of physical health conditions including diabetes, hypertension, cardiovascular diseases and cancers of the breast, endometrium, colon, kidney and esophagus. Obesity and physical inactivity may account for 25 to 30 percent of these major cancers. According to the Centers for Disease Control and Prevention, heart disease (25.5%), cancer (21.6%), stroke (6.8%), diabetes (5.0%) and kidney disease (3.2%) were the leading causes of death for Black women in 2006; all of which have been linked to the increasing rate of obesity among Black women.
What is the "obesity-depression" paradox?
There is a strong link between obesity and depression. Despite the fact that Black women have the highest risk of being overweight and obese than other racial and ethnic groups, have greater exposure to socioeconomic stress and higher levels of psychological distress, Black women have lower rates of depression (7.6%) compared to non-Hispanic white (12.7%) and Hispanic (9.9%) women. Thus, the overall pattern of obesity and depression observed among Black women seems counterintuitive at first glance.
The CTSI funded pilot study
Dr. Lincoln has completed three studies to examine the obesity-depression paradox and the pathways linking race and ethnicity to obesity and depression. In Dr. Lincoln's view, prior efforts to understand obesity disparities have been impeded by a lack of attention to social determinants of health and mental health as well as to heterogeneity within the Black American population. Dr. Lincoln was funded by the CTSI to conduct a study that investigated the psychosocial and health behavior pathways that might explain the relationship between depression and obesity among a diverse sample of Black women.
What did Dr. Lincoln find?
To address the question of whether stress might explain the relationship between health behaviors, obesity and depression, Dr. Lincoln tested the hypothesis that physical activity would reduce the negative effects of three different types of social stressors - chronic stress, material hardship and discrimination - on obesity and depression risk among women. She also speculated that the relationships would be different for Black women compared to non-Hispanic white women.
Dr. Lincoln found racial and ethnic differences in the association between stress, obesity and depression. Among Caribbean Black women, physical activity did not significantly reduce the effects of any of the stressors on obesity or depression risk. Among white women, however, physical activity reduced the effect of discrimination on obesity risk for those women who reported experiencing both high and low levels of discrimination. Among African American women, physical activity significantly reduced the effect of chronic stress on depression and obesity risk but only for those women who reported experiencing high levels of chronic stress. Physical activity had no effect on depression or obesity risk for African American women who reported experiencing low levels of chronic stress.
In light of recent findings that Black adolescent girls do not reap as many benefits from physical activity as white adolescent girls, findings from this work suggests that physical activity is beneficial but more so for women who are experiencing high levels of stress. Another interesting finding from this project is that depression had a curvilinear or U-shaped relationship with body mass index (used to measure obesity) in a sample of men and women. Specifically, African American, Caribbean Black and non-Hispanic white men and women who were overweight had the lowest risk for depression compared with those who were normal weight or obese. This finding may provide some evidence that certain health compromising behaviors such as consuming high sugar, high-fat meals and low physical activity increase the risk for being overweight but also have an acute suppressive effect on perceptions of stress which ultimately lowers the risk for depression.
Next steps
Based on these finding, Dr. Lincoln is collaborating with colleagues at USC, University of Virginia and University of Pittsburgh to use electrical engineering and systems science technology to prevent and treat obesity in families. Combined, findings from this work will contribute powerfully towards identifying potentially modifiable factors and critical junctures for prevention and intervention, and to the development of transdisciplinary theories of behavior and behavior change related to obesity.
