Association Between Negative Age Stereotypes and Accelerated Cellular Aging: Evidence from Two Cohorts of Older Adults

To the Editor: Negative age stereotypes, which are defined as disparaging beliefs about older persons as a category, have been linked to higher rates of physical and cognitive decline and mortality in older adults.1-5 However, no known study has evaluated whether these stereotypes are associated with shorter telomere length, a marker of accelerated cellular aging that provides a cumulative measure of cell divisions and exposures to genotoxic and cytotoxic processes such as oxidation and inflammation.6 Characterization of this association may provide insight into a possible molecular mechanism linking negative age stereotypes to accelerated functional decline and mortality and may inform prevention and treatment strategies designed to mitigate functional decline and preserve quality of life in older persons. The hypothesis that negative age stereotypes would be associated with shorter telomere length was evaluated in two diverse cohorts of older adults at higher risk of stress than their same-aged peers: older U.S. military veterans, who have higher rates of exposure to traumatic life events such as combat, and older adults who recently experienced an acute myocardial infarction (AMI). Two cohorts of community-dwelling individuals aged 60 and older were included in this study. The first sample (n = 335) participated in the National Health and Resilience in Veterans Study (NHRVS), a nationally representative, prospective cohort study of U.S. military veterans. Poststratification weights were applied in analyses to ensure generalizability of results to the U.S. veteran population. The second sample, older adults who had experienced an AMI in the preceding 2 weeks (n = 148), was recruited from four hospitals in two major Connecticut cities. Inclusion criteria included meeting the Enhancing Recovery in Coronary Heart Disease study definition of AMI and a score of at least six on the Short Portable Mental Status Questionnaire. Local institutional review boards approved both studies, and all participants provided informed consent. At the baseline assessment of both studies, age stereotypes were assessed using a three-item version of the Expectations Regarding Aging (ERA)-12 Survey,7 which assesses age stereotypes in physical health, mental health, and cognitive domains. These items ("Every year that people age, their energy levels go down a little more" [physical aging stereotype]; "It's normal to be depressed when you are old" [mental health aging stereotype]; "Forgetfulness is a natural occurrence just from growing old" [cognitive aging stereotype]), which had the highest-magnitude factor loadings, with respective factors assessing physical, mental, and cognitive age stereotypes,7 were summed to yield a measure of negative age stereotypes (range 0–9). Deoxyribonucleic acid (DNA) kits were used to collect saliva samples 4 years after the baseline assessment in the veteran sample and 1 year after the baseline assessment in the AMI sample; telomere length was determined using a fluorescence-based quantitative polymerase chain reaction assay.8 A ratio between the cycle threshold (Ct) values of each experimental sample and the Ct values of the reference gene standards was established. The final relative Ct ratio was determined by dividing the Ct telomere value by the Ct reference gene value for each sample. Ratios of less than 1 were coded as shorter telomere length, and ratios of 1 or greater were coded as normal length. Descriptive statistics were used to summarize demographic and clinical characteristics of both samples. Binary logistic regression analyses were then conducted to evaluate predictors of telomere length. Scores on the three-item version of the ERA were entered as independent variables and telomere length as the dependent variable. Covariates are shown in the Table 1 footnote. Table 1 shows sample characteristics and results of analyses of predictors of short telomere length in the veteran and AMI samples. After adjustment for covariates, higher ERA scores were independently associated with shorter telomere length in both samples (odds ratio (OR) = 1.30 in veterans, OR = 1.33 in older adults with AMI). As hypothesized, negative age stereotypes predicted shorter telomere length. This association emerged in two diverse cohorts and was independent of sociodemographic characteristics, as well as a broad range of physical and mental health indicators. Specifically, each point increase on the negative-age-stereotype measure (range 0–9 points) was associated with a 30–33% greater likelihood of having shorter telomeres. It was not possible to examine the direction of the association between negative age stereotypes and telomere shortening, but previous research suggests that age stereotypes, which tend to be established early in life, precede changes in health outcomes and functioning.1-5, 9 Further research is needed to examine interrelationships between serial measures of negative age stereotypes and telomere length; determine mechanisms linking age stereotypes to shorter telomere length; and evaluate the benefits of age-stereotype interventions for telomere length, other markers of physiological aging, and overall health and functioning. Possible mechanisms, suggested by previous research, that may account for the relationship between negative age stereotypes and shorter telomeres include greater stress reactivity, lower self-efficacy, and less engagement in healthy behaviors.1, 2, 9 Given that exposure to implicit age stereotypes can modify age stereotypes,10 such interventions may help prevent premature cellular aging and age-related functional decline.1-3, 9 Conflict of Interest: None. The U.S. Department of Veterans Affairs National Center for Posttraumatic Stress Disorder supported The National Health and Resilience in Veterans Study. Grants from the National Institute on Aging (AGR01AG032284), and the National Heart, Lung, and Blood Institute (R01HL089314) supported the cardiovascular study. Author Contributions: Pietrzak and Levy: study concept and design, first draft of manuscript. Pietrzak, Levy, Krystal, Southwick, Qi: data acquisition and interpretation, manuscript revision. Pietrzak, Slade: statistical analyses. Sponsor's Role: None of the sponsors had a role in the design, methods, subject recruitment, data collections, analysis, or preparation of the paper.