782 vII. APPLICATIONS  AND  IMPLICATIONS
based cohort of middle-  age women during 
the peri- and postmenopausal years, showed 
prospective relations between negative emo -
tionality and clinical measures of health 
status. Women in the HWS who were more 
depressed, tense, and angry at baseline were 
at increased risk of developing the metabolic 
syndrome during the 7–8 years of follow-  up 
(Räikkönen, Matthews, & Kuller, 2002). 
Importantly, though, this study also found 
reciprocal effects: Metabolic syndrome at 
baseline predicted increasing anger and anx -
iety over the follow-  up period. Relatedly, 
after menopause, the odds of heart disease 
increase significantly, and so do the odds of 
depression (Bromberger et al., 2011); depres -
sion is not causing disease.
In many studies, neuroticism predicts 
the reporting of symptoms but not the 
onset of actual disease (Costa & McCrae, 
1985; Feldman et al., 1999; Watson & Pen -
nebaker, 1989). This goes beyond the arti -
fact introduced when self-  report measures 
of health (negatively biased by neurotics) 
are used. Overall, trait neuroticism (low 
emotional stability) has not demonstrated 
consistent relations with health outcomes, 
including mortality. For example, the West -
ern Electric Study of middle-  age men (Al -
mada et al., 1991) did not show a relation 
between neuroticism and mortality. In the 
Million Women Study, a longitudinal inves -
tigation of a huge sample (Liu et al., 2016), 
middle-  age women were asked about their 
levels of relaxation, happiness, and “stress.” 
A decade of follow-  up, with many statistical 
adjustments possible due to the large num -
ber of participants, found no evidence that 
feeling stressed or unhappy itself increases 
cardiac risk, cancer risk, or overall mortality 
across the key years of middle age, despite 
an observed correlation between happiness 
and health.
A promising explanation for these con -
flicting results is that there are two quite 
different life paths involving neuroticism 
(Friedman, 2000). In one case, adults who 
were resentful and anxious failed to adhere 
to treatment regimens, engaged in an un -
healthy lifestyle, and had disturbed sleep, 
and/or evinced a lack of social support, all 
of which increase the risk of poor health. 
The other pathway—“healthy neuroticism” 
(Friedman 2000)—led to better health as a consequence of neurotic vigilance, cau -
tion, and treatment adherence (Gardner & 
Oswald, 2004; Korten et al., 1999; Weston 
& Jackson, 2015; see Friedman, 2019, for 
an overview). As noted earlier, the effects 
of neuroticism are further complicated by 
evocative effects, with neurotics tending to 
experience more negative events and react -
ing more strongly to them (Bolger & Zuck -
erman, 1995). Depression interventions for 
patients who have experienced a heart attack 
often have had no impact on the likelihood 
of subsequent heart attacks or mortality risk 
(Writing Committee for the ENRICHD In -
vestigators, 2003; see also McCaffery et al., 
2006; Whalley et al., 2011).
The effects of neuroticism may take time 
to build up (the cumulative model), in which 
case these effects should be strongest in old 
age (Wilson et al., 2004). Mroczek, Spiro, 
Griffin, and Neupert (2006) proposed that 
people who experience high levels of neurot -
icism throughout their lives develop a hair- 
trigger response to negative emotion. Ac -
cording to this “kindling hypothesis,” people 
with a life history of high levels of neuroti -
cism have consistently reacted strongly and 
negatively to stress, and, over the years, this 
has had a cumulative, detrimental effect on 
the HPA axis. Using data from the Norma -
tive Aging Study, Mroczek and Spiro (2007) 
showed that increasing neuroticism was as -
sociated with increased mortality risk over 
a 10-year period (mean age 63 for the per -
sonality assessments). Sometimes, relative 
change on a particular trait, rather than ab -
solute level, is the parameter with the most 
predictive power.
Positive Emotionality and Optimism
Positive emotionality in childhood is associ -
ated with both beneficial and detrimental 
long-term consequences for health. The neg -
ative consequences of positive emotionality 
are most starkly demonstrated in survival 
analyses for participants in the Terman Life 
Cycle Study. Contrary to popular wisdom, 
the Terman study indicated that childhood 
cheerfulness (a combination of cheerfulness/
optimism and sense of humor) increased 
mortality risk (Friedman et al., 1993). No 
simple explanation for this association was 