Significance
Optimism
is a psychological attribute characterized as the general expectation
that good things will happen, or the belief that the future will be
favorable because one can control important outcomes. Previous studies
reported that more optimistic individuals are less likely to suffer from
chronic diseases and die prematurely. Our results further suggest that
optimism is specifically related to 11 to 15% longer life span, on
average, and to greater odds of achieving “exceptional longevity,” that
is, living to the age of 85 or beyond. These relations were independent
of socioeconomic status, health conditions, depression, social
integration, and health behaviors (e.g., smoking, diet, and alcohol
use). Overall, findings suggest optimism may be an important
psychosocial resource for extending life span in older adults.
Abstract
Most
research on exceptional longevity has investigated biomedical factors
associated with survival, but recent work suggests nonbiological factors
are also important. Thus, we tested whether higher optimism was
associated with longer life span and greater likelihood of exceptional
longevity. Data are from 2 cohorts, women from the Nurses’ Health Study
(NHS) and men from the Veterans Affairs Normative Aging Study (NAS),
with follow-up of 10 y (2004 to 2014) and 30 y (1986 to 2016),
respectively. Optimism was assessed using the Life Orientation
Test–Revised in NHS and the Revised Optimism–Pessimism Scale from the
Minnesota Multiphasic Personality Inventory-2 in NAS. Exceptional
longevity was defined as survival to age 85 or older. Primary analyses
used accelerated failure time models to assess differences in life span
associated with optimism; models adjusted for demographic confounders
and health conditions, and subsequently considered the role of health
behaviors. Further analyses used logistic regression to evaluate the
likelihood of exceptional longevity. In both sexes, we found a
dose-dependent association of higher optimism levels at baseline with
increased longevity (P trend < 0.01). For example, adjusting
for demographics and health conditions, women in the highest versus
lowest optimism quartile had 14.9% (95% confidence interval, 11.9 to
18.0) longer life span. Findings were similar in men. Participants with
highest versus lowest optimism levels had 1.5 (women) and 1.7 (men)
greater odds of surviving to age 85; these relationships were maintained
after adjusting for health behaviors. Given work indicating optimism is
modifiable, these findings suggest optimism may provide a valuable
target to test for strategies to promote longevity.
As life span has increased in industrialized countries, exceptional longevity—commonly defined as survival to 85 y (1)—has
become less rare. Research across diverse organisms consistently
demonstrates that increases in life span are often accompanied by
delayed morbidity (2).
Therefore, factors that promote exceptional longevity are highly
relevant to public health as they may extend the duration of good health
(also known as “health span”; ref. 3).
Research on exceptional longevity has largely focused on identifying
biomedical factors (e.g., genetic variants) associated with increased
survival, but emerging evidence suggests nongenetic factors also
contribute. Recent epidemiologic studies have identified psychosocial
assets such as optimism as potential predictors of longer life, based on
findings linking higher optimism to reduced risk of developing chronic
diseases of aging and premature mortality (4⇓⇓⇓⇓⇓–10).
Importantly,
psychosocial assets are associated with health outcomes above and
beyond their role in signaling the absence of poor psychosocial
functioning (11), such as depression (4), and independent of sociodemographic confounders, health conditions, and health behaviors (12, 13).
Identifying diverse positive assets that promote health across the life
course, particularly in aging, could contribute to optimal functioning
and improved health. Among psychosocial factors that appear to be
potential health assets (e.g., social integration; ref. 14),
optimism has some of the strongest and most consistent associations
with a wide range of health outcomes, including reduced risk of
cardiovascular events, lung function decline, and premature mortality (4⇓⇓⇓⇓⇓–10), and associations that are independent of other psychosocial factors such as depression, anxiety, or anger (12).
Investigators have speculated that optimism may facilitate healthier
biobehavioral processes, and ultimately longevity, because optimism
directly contributes to how goals are translated into behaviors (15).
Optimism is ∼25% heritable but is also shaped by social structural
factors and can be learned, as demonstrated in experimental research
(e.g., refs. 16 and 17).
Higher levels of optimism have been linked to reduced risk of premature mortality (4); however, researchers have not considered the association between optimism and achievement of exceptional longevity (18⇓–20).
Although no standard definition for exceptional longevity has been
established, it has been defined as surviving to older age, and age 85
is a commonly used cutoff (1, 21)
as it is well beyond the average life expectancy of individuals born in
the early 20th century, but not extremely rare. Using data from 2
long-running observational cohorts composed of men or women, we
evaluated the hypothesis that higher optimism is associated with longer
life span and a greater likelihood of achieving exceptional longevity.
We considered associations in men and women, and accounted for potential
confounders identified in prior work, including other psychosocial
factors, baseline health conditions, and health behaviors (4, 6).
Results
We
conducted analyses among 69,744 women from the Nurses’ Health Study
(NHS) and 1,429 men from the Veterans Affairs (VA) Normative Aging Study
(NAS). NHS women have been followed since 1976 with biennial
questionnaires; they completed an optimism assessment in 2004 and
mortality status was tracked until 2014. NAS men have been followed
starting in 1961; they completed an optimism assessment in 1986 and
mortality status was tracked through 2016. The cohorts used different
measures of optimism, which prior work has demonstrated to be correlated
(ref. 22; see SI Appendix, section S5 for details). We operationalized optimism as a continuous variable using z
scores (standardized against sample-specific mean and SD) and also as a
categorical variable. In NHS, we created quartiles of optimism scores,
and we used quintiles for NAS as the NAS measure has more items and a
broader scoring range.
Descriptive statistics by optimism categories in each cohort are presented in SI Appendix, Table S1.
At baseline for these optimism analyses, NHS and NAS participants were
on average 70 and 62 y old, respectively, were predominantly white, and
were married. Qualitatively, women with higher levels of optimism were
less likely to have an associate/registered nurse degree (compared to
bachelor’s, master’s, or doctoral degrees), and less likely to report
some health conditions, especially depression and type 2 diabetes. Men
with higher levels of optimism had higher levels of education and family
income; they were less likely to report depressive symptoms and have
type 2 diabetes, and reported less alcohol use, and somewhat lower body
mass index (BMI). Both men and women with higher optimism were more
likely to engage in physical activity. While many variables in SI Appendix, Table S1
showed statistically significant differences across optimism
categories, especially for NHS, primarily due to the large sample size,
we focused on the magnitude of differences rather than strictly on
statistical significance in interpreting findings.
We
used accelerated failure time (AFT) models to test whether higher
baseline levels of optimism were associated with greater longevity, as
indicated by a longer life span. During the 10- and 30-y follow-up
periods for NHS and NAS, 13% of the 69,744 women and 71% of the 1,429
men died, respectively. In NHS, higher levels of optimism were
associated with extended life span in all models (Table 1, NHS; P
trend ≤ 0.0001). For example, in a model adjusted for demographics,
baseline health conditions, and depression, women in the highest versus
lowest quartile of optimism had a life span 14.9% longer (95% confidence
interval [CI]: 11.9%, 18.0%). To contextualize the magnitude of these
estimates, in this model, never having been diagnosed with type 2
diabetes was associated with 17.0% (95% CI: 14.4%, 19.6%) longer life
span and never having been diagnosed with myocardial infarction was
associated with 18.0% (95% CI: 14.7%, 21.4%) longer life span. After
additionally adjusting for health behaviors, the associations were
substantially attenuated but remained statistically significant. For
example, in the fully adjusted models, the highest versus lowest
quartile of optimism was associated with an 8.7% (95% CI: 5.8%, 11.6%)
longer life span. While it is possible that health behaviors are
confounders in this association, such behaviors may also lie on the
pathway linking optimism to longevity (23).
Table 1. Percent differences in life span associated with optimism in NHS, 2004–2014 (n = 69,744), and NAS, 1986–2016 (n = 1,429)
For men in NAS, higher baseline optimism levels were similarly related to longer life span (Table 1, NAS; P
trend = 0.002). After adjusting for demographics, baseline health
conditions, and depression, compared to the least optimistic men, those
in the highest quintile had 10.9% (95% CI: 1.3%, 21.5%) longer life
span. As a point of reference, in this model, never having been
diagnosed with type 2 diabetes was associated with a 13.1% (95% CI:
2.7%, 22.5%) longer life span, and never having been diagnosed with
heart disease was associated with 16.6% (95% CI: 10.4%, 22.4%) longer
life span. After further adjusting for health behaviors, the association
between higher levels of optimism and longer life span remained
significant but was attenuated, similar to findings in women; life span
was 9.8% longer (95% CI: 0.3%, 20.3%) in the top versus bottom quintile
of optimism.
In further analyses using logistic
regression models restricted to individuals who had the potential to
reach age 85 by the end of mortality follow-up for each cohort, we
assessed whether higher optimism levels were associated with greater
odds of achieving exceptional longevity. In NHS, of the 13,045 women
born early enough to be eligible for these analyses, 86% survived to age
85 or beyond. Higher optimism was associated with greater odds of
achieving exceptional longevity, with a positive trend evident across
optimism levels (Table 2, NHS; P
trend < 0.01). After adjusting for demographics, baseline health
conditions and depression, compared to women in the lowest quartile, the
odds ratios (ORs) for exceptional longevity for women with higher
optimism levels ranged from 1.2 (95% CI: 1.1, 1.3) in the second lowest
quartile to 1.5 (95% CI: 1.2, 1.7) in the highest quartile. After
further adjusting for baseline health behaviors, estimates were
attenuated but remained statistically significant.
Table 2. Odds ratios for the association of optimism with survival to age 85+, NHS (n = 13,045) and NAS (n = 1,117)
In
NAS, of the 1,117 men born early enough to be eligible for these
analyses, 56% survived to age 85 or beyond. Higher optimism was also
associated with greater odds of achieving exceptional longevity (Table 2, NAS; P
trend < 0.01). Adjusting for demographics, baseline health
conditions, and depression, compared to men in the least optimistic
quintile, ORs for exceptional longevity were larger for men with higher
optimism levels, ranging from 1.5 (95% CI: 1.0, 2.3) in the second
lowest quintile to 1.7 (95% CI: 1.1, 2.6) in the highest quintile (both
values of P < 0.05). After adding health behaviors to the
model, the 2 highest optimism quintiles remained significantly related
to higher odds of achieving exceptional longevity.
We
conducted several sensitivity analyses. First, to address potential
concerns regarding residual confounding between optimism and baseline
health conditions, we repeated the AFT and logistic regression analyses
after excluding respondents with major chronic diseases at baseline (N excluded: 15,952 in NHS, 294 in NAS). Results remained comparable to those reported above (SI Appendix, Tables S2 and S3).
However, fewer associations reached statistical significance, likely
due to the reduced sample sizes. We also tested possible confounding by
other psychosocial assets that may promote longevity. In particular,
social integration, as indicated by the presence of ties to multiple
social networks (e.g., marriage, friendship), is correlated with
optimism (24), has consistently predicted survival across multiple studies, and has a strong association with survival (14).
When we included social integration in the AFT analyses, the
associations of optimism to longer life span were somewhat attenuated
but remained statistically significant in both cohorts (SI Appendix, Table S4).
We did not also consider logistic regression models of survival to age
85 with the additional social integration covariate; NHS women who had
the potential to reach age 85 represented 19% of the overall population,
and as they were older at baseline, as expected, had more missing data.
Thus, adding social integration variables to models would further
reduce the eligible sample, yielding concern regarding the validity of
analyses with this subset.
Discussion
In
2 long-term, longitudinal cohorts of women and men, higher optimism
levels were associated with longer life span and higher odds of
achieving exceptional longevity. These associations were maintained
after adjusting for demographics and baseline health conditions.
Accounting for baseline health behaviors that could confound the
association or potentially also lie on the pathway between optimism and
longevity attenuated the associations, but findings remained significant
and comparable in magnitude between men and women. A unique feature of
this study is the focus on exceptional longevity. While prior studies
have reported that optimism may reduce risk of premature death in mid-
and later life, the current findings suggest that optimism promotes
substantially longer life span. As longer life span appears to accompany
longer health span (3), our findings have implications for understanding psychosocial factors that promote healthy and resilient aging.
Our findings are consistent with and extend those from our own (4) and other studies (9, 25)
reporting associations between higher optimism and lower all-cause
mortality risk. In 941 older Dutch adults followed for a decade, Giltay
et al. (25)
reported optimism was more strongly related to reduced risk of
premature mortality in men (42 to 53% risk reduction in multivariate
models) than women (9 to 31% risk reduction), although there was lower
statistical power to detect an association in women than men. The
present study included larger samples of women (N = 69,744) and men (N
= 1,429), and a lengthier follow-up for men (30 y). We observed similar
effect sizes between sexes and findings were robust across these 2
independent cohorts.
Other strengths of our study
include the ability to consider a broad set of covariates related to
both optimism and longevity. We did not find that existing health
conditions introduced meaningful confounding in the relation of optimism
to life span. In analyses considering both life span and likelihood of
achieving exceptional longevity, associations with optimism were largely
maintained after adjusting for numerous physical health conditions at
baseline, including high cholesterol, hypertension, type 2 diabetes,
heart disease, stroke, and cancer. Furthermore, associations withstood
adjustment for depression, suggesting optimism does not simply signal
the absence of psychological distress and related risks, but rather may
confer independent benefits for longevity.
Given studies
documenting strong linkages between optimism and greater engagement in
healthy behaviors, health behaviors may provide a mechanism linking
optimism to longevity (26).
In the present study, we note that the estimates for optimism were
consistently attenuated when adjusted for a large panel of health
behaviors at baseline, including smoking, alcohol use, physical
activity, diet, BMI, and primary care visits. Optimistic individuals
tend to have goals and the confidence to reach them; thus, optimism may
foster health-promoting habits and bolster resistance of unhealthy
impulses through greater engagement with one’s goals, more efficacious
problem-solving, and adjustment of goals when they become unattainable (11).
In
addition to promoting healthier behaviors, there are other potential
explanations for the associations of optimism to longer life span.
Considering psychosocial pathways, more optimistic individuals may
experience less extreme emotional reactivity to, and faster recovery
from, acute stressors (27).
When faced with difficulties, more optimistic individuals appear to
have better capacity to regulate emotions through cognitive routes, such
as reframing situations as challenges rather than threats, or through
behavioral mechanisms, such as resisting immediate rewards in service of
longer-term goals (11, 28).
Considering biological pathways, higher levels of optimism have been
linked to healthier biomarker profiles in the cardiovascular (7), metabolic (29), immune (30), and pulmonary (10)
systems. Given research identifying an increasing number of
psychosocial assets for good health, an issue to consider is unique vs.
shared variance among these attributes. In sensitivity analyses, we
found that adjusting for social integration somewhat attenuated but did
not fully account for the association of optimism to extended life span,
providing support for some independent effects. However, additional
work might consider potential additive effects among psychosocial assets
and whether there are critical health-beneficial components shared
across assets.
Several limitations should be considered.
First, both cohorts were mostly white and had higher socioeconomic
status than the general population, therefore findings may not
generalize to racial/ethnic minorities and more socioeconomically
disadvantaged populations. Other studies in US populations have
generally found that individuals with higher education, income, and
occupational status have higher optimism levels (31), although racial and ethnic differences are less clear (9, 31) and may be modified by other sociodemographic factors such as household income (32).
However, few studies have examined these relationships. Most
importantly, associations of optimism with health outcomes persist
across diverse groups, although evidence is also limited (9, 33).
Taken together, this work suggests that while some groups may
differentially attain higher optimism levels, the apparent health
benefits are similar across groups. Second, we examined associations
among middle-aged and older adults in both cohorts. It is unclear how
earlier-life processes might shape both optimism and likelihood of
exceptional longevity. However, optimism appears to be highly stable in
adulthood (e.g., 5-y correlation = 0.87 in NAS); thus, aging-related
changes in optimism are unlikely to have a strong impact on our
findings. Third, reverse causality is possible, whereby less healthy or
already-ill individuals are less optimistic at study baseline, and
therefore less likely to achieve exceptional longevity. However, our
primary analyses excluded those who died early in the follow-up, and the
pattern of findings remained stable in sensitivity analyses that
excluded individuals with major chronic diseases at baseline.
Together
with other work, our findings suggest optimism serves as a
psychological resource that promotes health and longevity. If so, then
optimism offers a valuable target for interventions seeking to promote
health by fostering psychological resources. This approach would be
somewhat different from more mainstream approaches that often aim to
mitigate or repair psychological deficits. A recent meta-analysis of 29
studies showed that relatively brief interventions can enhance optimism (34),
although this work has not followed participants over the long term.
Interventions range from brief writing exercises and meditation to more
intensive cognitive-behavioral therapy practices. Recent work has
evaluated the feasibility of conducting 8-wk interventions to increase
optimism and other facets of psychological well-being in cardiac
patients (35).
Future research should address whether improvements in optimism will
translate into behavioral or health benefits in the short or long term.
In
conclusion, we found higher optimism levels were associated with longer
life span and greater likelihood of achieving exceptional longevity.
Importantly, these associations were replicated across 2 independent
cohorts and remarkably similar in magnitude in men and women, after
adjusting for potential confounders and possible intermediate variables.
Given research showing that increasing health span often accompanies
increasing life span, our findings suggest optimism may be an important
psychosocial resource in promoting healthy aging (33).
Such findings add to the arsenal of potentially modifiable factors that
should be targeted to improve population health and longevity.
More at link.
