personality, intelligence & health - lecture 10

Graham et al. (2017) • Personality predicts mortality risk: An integrative data analysis of 15 international longitudinal studies • Paper: Deary, Weiss & Batty (2010) • Intelligence and personality as predictors of illness and death: How researchers in differential psychology and chronic disease epidemiology are collaborating to understand and address health inequalities

openness

openness to new experiences
• Intellectually curious, unconventional thinking, active imagination

conscientiousness

degree of self-discipline and control
• Organised, determined, careful, goal-oriented

extraversion

sociability
• Sociable, energetic, optimistic, friendly, assertive
• Agreeableness: cooperation and social harmony
• Trusting, helpful, soft-hearted, sympathetic

neuroticism

emotional stability
• Mood swings, volatile in their emotions

friedman et al 1995- health behaviour model

Some personality traits predispose individuals to:
• Engage in health promoting behaviours
• Reframe from health risk behaviours
• Personality → healthy behaviours → better health
• Health behaviours: mechanisms linking personality to health

conscientiousness and health

May be more likely to take part in health promoting behaviours
• May be less likely to take part in risky health behaviours
• May be more efficient in dealing with medical issues (i.e., seeing a doctor earlier)
• May be more careful about managing a disease if they develop one
• More likely to be healthy overall

godwin and friedman- personality and disease

Cross-sectional study: Big Five and mental and physical health
• Midlife Development in the United States Survey (MIDUS)
• 1995-1996: telephone interview and mailed questionnaires
• Nationally representative sample of 3,032 adults aged 25 to 74 years
• Personality: Midlife Development Inventory Personality Scales (MIDI)
• Based on the ‘big-five’
• Likert-type scale. Describe how often they were e.g., “organised”,
“responsible”, “hardworking”
• 1 = a little; 2 = some; 3 = most; 4 = all
• Score ranging between 1 and 4 for each personality trait

goodwin and friedmanm- mental disorders

Composite International
Diagnostic Interview Short-
Form scales
• Major depression
• Panic attacks
• Generalised anxiety
disorder
• Alcohol and substance use
disorders

goodwin and friedmanm- physical illness

assessed by
self-report in past 12 months
• Asthma/chronic bronchitis/emphysema
• Tuberculosis
• Other lung disease
• Persistent skin problems
• Sciatica/lumbago (lower back pain)
• Urinary/bladder problems
• High blood pressure
• Diabetes/high blood sugar
• stroke
• Ulcer
• Bone/joint problems
• Hernia/rupture

goodwin friedaman conclusions

Limitation: Cross-sectional study
• Cannot and does not attempt to establish causal links between
personality and health
• Low conscientiousness consistently associated with poor health
• Size of associations with health were larger for conscientiousness
than other personality traits
• Low neuroticism also associated with poor health
• Conscientiousness → health-promoting behaviours → improved
health

personality and death- graham 2017

Higher levels of conscientiousness were associated with a lower
mortality rate
Hazard Ratio (HR) = 0.89 (95% CI 0.85 to 0.95) down 11%
• Higher levels of extraversion and agreeableness were associated
with lower mortality rate
• Extraversion HR = 0.94 (0.90 to 0.99) down 6%
• Agreeableness HR = 0.95 (0.93 to 0.96) down 5%
• High levels of neuroticism were associated with increased mortality rate
• HR = 1.05 (95% CI 1.03 to 1.07) up 5%
• Openness was not associated with mortality

graham et al- personality and smoking

Higher levels of neuroticism and extraversion were associated
with greater likelihood of being a smoker (2% to 7% increased
risk)
• Openness, conscientiousness, and agreeableness were not
associated with likelihood of smoking

smoking and mortality

Individuals who were current smokers had an increased risk
of mortality
• HR = 1.70 (95% CI 1.45 to 2.00) up 70%

personality, smoking and mortality

The indirect effect of personality on mortality, via smoking status
• Small mediation effect of smoking on the neuroticism-mortality
association
• Smoking did not mediate the personality-mortality association for all other personality traits

graham conclusions

Replicated previous work that conscientiousness and
neuroticism are associated with mortality
• New: Found extraversion and agreeableness were also
associated with lower risk of mortality
• Mechanisms
• Smoking mediated neuroticism-mortality association
• Higher neuroticism → smoker → risk of death
• Personality → health behaviours → health
• Some support of the health behaviour model of personality
• Limitation: Only looked at current smoking status

neuroticism and health

Neuroticism: negative affect and emotional instability
• Often associated with poor health
• But neuroticism may influence health through multiple pathways
• Neuroticism may also be beneficial to health

friedman 2000- healthy neuroticism

Hypothesised that, under certain circumstances,
neuroticism can have a positive impact on health
• 'Neurotic vigilance’
• Trait interaction of neuroticism and conscientiousness
Healthy neuroticism:
• High neuroticism & high conscientiousness → better health
Unhealthy neuroticism:
• High neuroticism and low conscientiousness → poor health

healthy neuroticism and health behaviours

Neuroticism was not associated with health behaviours
• Conscientiousness was consistently associated with health
promoting behaviours
• Low conscientiousness: odds of smoking increase and odds of
being regularly physically active decrease for individuals higher in
neuroticism
• High conscientiousness: neuroticism is not associated with
smoking or physical activity

Higher conscientiousness reduces the negative impact of
neuroticism on smoking and physical activity
• Evidence that healthy neuroticism is associated with health
promoting behaviours but effects are small

healthy neuroticism and chronic conditions

Higher neuroticism was associated with:
• Greater odds of reporting all chronic conditions cross-sectionally
• Greater odds of prospectively reporting hypertension
• Higher conscientiousness was associated with:
• Reduced odds of reporting all chronic conditions cross-sectionally
• Reduced odds of reporting diabetes and heart disease
• No evidence that the relationship between neuroticism and
chronic conditions vary by level of conscientiousness
• No evidence that healthy neuroticism is associated with chronic
conditions

healthy neuroticism and dying - Turiano et al

Evidence that higher conscientiousness was associated with
reduced risk of mortality
• Evidence that higher neuroticism was associated with
increased risk of mortality
• No evidence that higher levels of neuroticism were associated
with mortality risk only when conscientiousness was low
• No evidence that healthy neuroticism was associated with personality

personality and health conclusions

Evidence that neuroticism is associated with:
• Higher rates of chronic disease
• Cross-sectionally: Hypertension, diabetes, heart disease
• Prospectively: Hypertension
• Greater risk of death
Evidence that conscientiousness is associated with:
• Health promoting behaviours
• Not smoking, not drinking, physical activity
Lower rates of chronic disease
• Cross-sectionally: Hypertension, diabetes, heart disease
• Prospectively: Diabetes, heart disease
Lower risk of death

healthy neuroticism- integrative analysis

There is evidence that healthy neuroticism is associated with
engaging in more health promoting behaviours
• Not smoking, physical activity
• No evidence that healthy neuroticism is associated with chronic
disease or risk of death
• Effect on health behaviours may not be large enough to
translate to differences in health outcomes
• Conscientiousness may dampen the behavioural tendencies in
individuals with high neuroticism
• But conscientiousness does not appear to reduce the
physiological stress experienced by those with trait anxiety

integrative analysis studies- evaluation

Based on Western samples
• Self-reported data: health behaviours and chronic diseases
• Biased sample: Personality traits are associated with taking part
in studies, and repeatedly taking part in studies
• Limited by the data available in the studies included
• Only considered personality traits, not personality facets

facets

More specific personality attributes that cluster together and all
contribute to the factor score
• Possible that facets of neuroticism or conscientiousness drive
healthy neuroticism

neuroticism facets

Anxiety, anger, hostility, depression, self-consciousness, impulsiveness, vulnerability to stress

conscientiousness facets

Competence, order, dutifulness, achievement striving, self-discipline and deliberation

intelligence and health - reverse causation

A direction of association between two variables is different from
what you would expect
• The presumed outcome precedes the exposure
• Often assumed:

disease causes lower IQ

but sometimes the relationship is actually the other way around-

lower IQ causes disease

reverse causation is?

bidirectional

intelligence and death

IQ-death associations in 70,805 people who took an intelligence
test at age 11 and were traced 68 years later

• 1 SD higher age 11 IQ (equivalent of 15 IQ points) associated
with 20% lower risk of death
• HR = 0.80 (95% CI 0.79 to 0.81) down 20%
• Slightly stronger in women than men
• Women HR = 0.79 (95% CI 0.77 to 0.80) down 21%
• Men HR = 0.82 (95% CI 0.81 to 0.84) down 18%

calvin et all 2010

Systematic review of the association between intelligence in youth
and mortality
• 16 studies from UK, USA, Sweden, Australia, and Denmark
• 1,107,022 participants
• Average age at testing ranged from 7 to 20 years
• 6 cohorts were all male
• Intelligence scores taken from school records (n = 10), military
service (n = 5), research database (n = 1)
• Range of intelligence tests (including WAIS, Stanford-Binet, Moray
House Test)
• Follow-up length ranged from 17 to 69 years

calvin 2010 results

22,453 deaths
• 1 SD higher intelligence (equivalent to 15 IQ points) associated
with 24% lower risk of death
• HR: 0.76 (95% CI 0.75-0.77) down 24%
• Similar for men and women

calvins subsamples with SES education

Adjustment for childhood socio-economic status did not
change the association
• HR = 0.77 (95% CI 0.75 to 0.79) down 23*
• Adjustment for adulthood socio-economic status attenuated
the association by 33.5%, but still associated
• 1 SD higher intelligence was associated with 16% lower risk of dying
• HR = 0.84, 95% CI 0.78 to 0.90) down 16%
• Adjustment for educational attainment attenuated the
association by 54.2%, but still associated
• 1 SD higher intelligence associated with 13% lower risk of dying
• HR = 0.89 (95% CI 0.86 to 0.91) down 11%

intelligence and death pathways

Childhood socioeconomic status did not attenuate the association between IQ and death
• Higher IQ → more education & higher SES in adulthood → better
health → reduced risk of death
• Educational attainment and adulthood SES partly attenuated the
association
• IQ may be associated with reduced risk of death via education and adult SES
• But IQ remained associated with risk of death even after adjusting for these variables

intelligence and disease lawlor et al

ssociations between childhood intelligence and cardiovascular
disease in midlife
• Aberdeen Children of the 1950s
• 12,150 individuals born in Aberdeen in 1950 and 1956
• IQ age 11: Moray House tests (verbal and numerical tests)
• Follow-up in middle age via health records
• Coronary heart disease
• Stroke

lawlor results

Intelligence was inversely associated with risk of cardiovascular
disease and stroke risk
• A 1 SD higher intelligence test score was associated with*:
• CHD HR = 0.70 (95% CI 0.61, 0.81)down 30%
• Stroke HR = 0.68 (95% CI 0.55, 0.84)down 32%
• CHD or Stroke HR = 0.68 (95% CI 0.61, 0.75)down 32%
• Associations were stronger in female participants than males
• Associations were reduced in size but remained even after
adjusting for:
• Early life socioeconomic status
• Family background
• Maternal pregnancy complications
• Childhood nutrition
*Adjusted for age and sex

metabolic syndrome and death

Higher IQ was associated with reduced odds of having metabolic
syndrome
• Higher IQ was associated with reduced risk of dying from:
• All causes
• Cardiovascular diseases
• Metabolic syndrome mediated the association between IQ and
mortality (especially for cardiovascular disease mortality)
• IQ may be associated with mortality via metabolic syndrome
Lower IQ → metabolic syndrome → mortality
Lower IQ → unhealthy behaviours → metabolic syndrome → mortality

intelligence and health behaviours

Higher intelligence has been associated with being more likely to:
• exercise regularly
• eat healthier diets (but more likely to skip meals and snack)
• not smoke and quit smoking
• avoid risky drinking behaviours (but they drink more alcohol)

intelligence and smoking

Intelligence in childhood was associated with
• Being a current smoker (Batty et al., 2007)
• Being an ever smoker (Batty et al., 2007)
• Quitting smoking (Batty et al., 2007; Taylor et al., 2003)
• Adjusting for childhood social class did not attenuate the
relationship (Batty et al., 2007)
• Adjusting for indicators of socioeconomic status partly or fully
attenuated the relationship between IQ and smoking

health literacy

degree to which an individual can find, use and
understand health information to successfully manage their health

mechanisms: system integrity

Underlying general physiological
make-up may influence both intelligence and health
• Higher intelligence test scores and lower rates of disease may
both be markers for a well-functioning body
• Last week: Davies et al. (2018) found shared genetic
influences between intelligence test scores and health-related
traits
• Many of the genetic variants associated with intelligence were also associated with health-related trait

disease prevention hypothesis

Many studies find that intelligence-health associations reduce or
disappear after statistical adjustment for education and adult
social class
• Suggest intelligence may be associated with health via
socioeconomic status
• Individuals with higher SES may have safer working and living
environments
Batty et al. (2005), Batty et al. (2007)
Higher intelligence → more education → higher socioeconomic status→ healthier environments → better health

personality, intelligence and health conclusion

ndividual differences in personality and intelligence
impact health

Personality is associated with health:
• Conscientiousness is consistently associated with better health
• Neuroticism is often associated with poorer health
• Healthy neuroticism is associated with healthy behaviours, but there is limited evidence it is associated with disease and death
Intelligence is associated with health:
• Lower intelligence is associated with death
• Lower intelligence is associated with disease
• Lower intelligence is associated with risky health behaviours