UNIVERSITY PARK, Pa. – A study by researchers in Penn State’s College of Health and Human Development (HHD) has been published in Brain, Behavior and Immunity, the official journal of the Psychoneuroimmunology Research Society.
The study, titled, “Daily positive events and inflammation: Findings from the National Study of Daily Experiences,” suggests that positive aspects of everyday life may accumulate over time to protect against inflammation and promote long-term health. Researchers include Nancy Sin, postdoctoral fellow in the Center for Healthy Aging and the department of biobehavioral health; Jennifer Graham-Engeland, associate professor of biobehavioral health; and David Almeida, professor of human development and family studies.
“In this study, we found that daily positive events were associated with lower levels of inflammation,” Sin said. “Previous research has shown that negative psychological states, such as stress and depression, are linked to elevated inflammation, which increases the risk of chronic diseases and death. We were interested in whether daily experiences of positive events could protect against inflammation.”
The researchers used data that was collected as part of the Midlife in the U.S. Study, a large national study of middle-aged and older adults. The sample of 969 participants were interviewed by telephone every evening for eight days. During the daily interviews, they were asked whether anything positive happened in each of these five life domains: at home, at work, positive social interaction, "network" event (positive event that happened to a close friend or relative) or any other positive event. The participants provided blood samples at a clinic visit, and these blood samples were analyzed for levels of three inflammatory markers: interleukin-6, C reactive protein and fibrinogen.
On average, participants experienced positive events on 73 percent of the interview days.
“These events are minor and common in everyday life, such as having lunch with a friend or engaging in a good conversation,” Sin said. “People who had more frequent positive events in their daily lives (defined as the percentage of days with at least one positive event) tended to have lower inflammation, compared to people who had fewer positive events.”
Additionally, the study suggests that daily positive events may be a source of resilience for people who are economically disadvantaged. Among lower-income participants, those who experienced more frequent positive events tended to have lower levels of interleukin-6, compared to low-income participants who had less positivity in daily life.
“Positive events that took place with someone else (interpersonal positive events) were more strongly associated with inflammation than positive events that happened alone,” Sin said.
The highest levels of inflammation were among people who had few positive events (less than 57 percent of days).
“But, more is not necessarily better,” Sin said. “People who had positive events on the majority of days tended to have the same inflammatory benefits as those who had positive events everyday.”