Research Spotlights: April 2019

research spotlight

Social isolation—Associations with physical activity and sedentary behavior

How interconnected we are to our communities can have profound impacts on health and longevity and is an increasing concern for aging populations. Recently, a study funded by NIA, the OBSSR, and the British Heart Foundation investigated if being lonely and/or isolated are associated with being less physically active in older adults. To date, there has been little research looking at these issues in aging populations, and most of this research uses self-report measures instead of objective measures.

Participants, who wore wrist-mounted accelerometers over 7 days (men, n = 136; women, n = 131; ages 50–81 years), were part of the English Longitudinal Study of Ageing (ELSA), a nationally representative panel study of people living in England at or above the age of 50. Social isolation and loneliness were assessed with standard questionnaires, and poor health, mobility limitations, and depressive symptoms were included as covariates. Associations between social isolation or loneliness and physical activity were analyzed using linear regressions.

Total physical activity was lower in isolated older adults compared with non-isolated persons, independent of gender, age, socioeconomic status, marital status, smoking, alcohol consumption, self-rated health, limiting longstanding illness, mobility limitations, depressive symptoms, and loneliness (β = −0.130, p = 0.028). Additionally, sedentary behavior was higher in isolated older adults (β = 0.143, p = 0.013). Loneliness was not associated with physical activity or sedentary behavior in this study. These findings suggest that greater social isolation in older men and women is associated with less physical activity and greater sedentary time. These changes in physical activity may contribute to the increased risk of ill health and poor well-being associated with social isolation.

Schrempft S, Jackowska M, Hamer M, Steptoe A. 2019. Associations between social isolation, loneliness, and objective physical activity in older men and women. BMC Public Health. 16;19(1):74.

Predicting the health risks of adverse childhood experiences; it’s complicated

Researchers sought to untangle the complex associations between adverse childhood experiences (ACEs) and increased risk for poorer socioeconomic, health, and emotional wellbeing outcomes in a recent study supported by NIA, NCATS, OBSSR, John D. and Catherine T. MacArthur Foundation, Georgetown University, and UCLA.

This study used two independent samples of twins and siblings from the United States: The Midlife Development in the United States (MIDUS) study (N = 862) and the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 3,112). Sibling comparison models, which control for latent sources of genetic and within-family environmental influences, were estimated to examine whether differential exposure to ACEs was associated with physical health, depressive symptoms, educational attainment, income attainment, alcohol problems, and antisocial behavior in adulthood.

In line with previous studies, the results indicated that families that experienced more adversity also experienced more negative outcomes. However, these associates were primarily driven by environmental (as opposed to genetic) factors clustered within families. Depressive symptoms in the MIDUS sample were the only exception where the genetic influences contributed to observed differences between within- and between-family effects. This study highlights that the current methods and strategies used for assessing ACEs may not fully capture the variety of sources of family-level environmental and genetic influences that are crucial in unraveling the effects of ACEs on future health and well-being.

Schwartz JA, Wright EM, Valgardson BA. 2019. Adverse childhood experiences and deleterious outcomes in adulthood: A consideration of the simultaneous role of genetic and environmental influences in two independent samples from the United States. Child Abuse Negl. 88:420-31.

Can genetics determine your cigarette preference? African Americans and menthol cigarette use

Recent research supported by NIDCR, NCATS, NIMH, NINDS, NIDA, NIH OD, and the FDA sought to determine if there is a genetic basis for the preference to smoke menthol cigarettes. Cigarette smoking remains a leading cause of preventable disease and mortality in the United States. Overall rates of smoking have declined dramatically over the last 50 years; however, the use of mentholated cigarettes has not declined and has increased in some groups. Additionally, evidence suggests that menthol cigarettes likely pose an even greater public health risk than nonmenthol cigarettes. In the United States, most African American smokers use mentholated cigarettes, as compared to Caucasian smokers, but whether this difference has a genetic basis, or is attributable solely to social or cultural factors, is unknown.

To determine if genetic variation contributes to mentholated cigarette smoking, the authors performed an exome-wide association analysis in a multiethnic, population-based sample from Dallas, Texas (N = 561), and then the findings were replicated in an independent sample of African Americans from Washington, D.C. (N = 741). The results revealed a significant association between menthol cigarette use and coding variants in MRGPRX4, which encodes a G protein-coupled receptor expressed in sensory neurons. The variant haplotype was found only in populations of African ancestry.

Menthol cigarettes have been identified as a public health threat that has a disproportionate effect on ethnic minorities. These data indicate that genetic variation contributes to the high rate of menthol cigarette use in African Americans. The existence of population-specific genetic variants provides a new risk factor for menthol cigarette use and can better inform health policies and tobacco regulatory actions aimed at reducing health disparities in the United States.

Kozlitina J, Risso D, Lansu K, Olsen RHJ, Sainz E, Luiselli D, et al. 2019. An African-specific haplotype in MRGPRX4 is associated with menthol cigarette smoking. PLoS Genet. 15(2): e1007916.