intelligence as a predictor of health, illness and death

Question 1

what is cognitive epidemiology concerned with?

Answer 1

• the age across which the intelligence-death associations apply
• which causes of death link with intelligence
• which types of physical and mental illness are associated with intelligence
• possible causes of these relationships

Question 2

what kinds of studies are needed to investigate this area?

Answer 2

cohort (longitudinal of people born in the same time period) studies with huge samples - eg a million people.

Question 3

what years were the scottish mental health survey’s first used?

Answer 3

1932 and 1947

Question 4

what did the scottish mental health surveys do? (SMHS)

Answer 4

tested the intelligence of everyone born in 1921 that attended school on a particular day.
- used the moray house test

Question 5

how many took part in scottish mental health surveys (1932 and 47)

Answer 5

1932 = approx 87,000
1947 = approx  70,000

Question 6

what was the original aim of the scottish mental health surveys? (SMHS)

Answer 6

to see who scored low so we could see what could be done about their promotional health

Question 7

whalley and deary (2001) did a follow up in 1997 - what did they find in terms of alive/dead?

Answer 7

• traced 79% of individuals from 1932 test in 1997.
  men: 646 died, 507 alive.
  women: 438 died, 594 alive. others could not be traced or had moved away.

Question 8

what conclusions did whalley and deary make about the data?

Answer 8

individuals who had died before 1997 had significantly lower mean IQ than those who were alive. (15IQ points)

Question 9

what explains the difference in mortality rates between men and women from 1932-1997?

Answer 9

world war.

even still, the follow up showed more high IQ men to be alive than low IQ.

Question 10

what explanations can be made for mortality rates and intelligence? (whalley and deary, 2001) (4)

Answer 10

• intelligence is a record of perinatal and childhood insults so tells us something about development
• intelligence predicts safer occupational or other environments eg more likely to live or work in safer places
• intelligence is a marker for a good general system integrity - those with higher IQ may just be wired better
• intelligence can predict better health behaviours and management of illness

Question 11

overall, what was the midspan studies of cardiovascular health able to show? (Hart et al., 2005)

Answer 11

confirmed the link between intelligence and mortality after combining the results with the 1932 cohort. (Hart et al., 2005)

Question 12

what did combining the 1932 and 1970 cohorts show about potential mediators?

Answer 12

something might moderate mortality and intelligence - you can have low IQ in childhood but having a socio-economic advantage can reduce your chances

Question 13

combining the 1932 cohort with the midspan studies showed what about health?

Answer 13

• a 15point IQ disadv. at age 11 was associated with a 17% higher risk of dying in the follow up period. this is reduced to 12% when taking occupation into account
• a sig association hetween childhood IQ and dying from cardiovascular disease and lung cancer
• low IQ in childhood was linked with a 16% increase of developing or dying from CHD (Hart et al., 2005)

Question 14

what did the scottish mental health survey show in terms of health outcomes from childhood IQ?

Answer 14

• lower childhood IQ was associated with lower integrity of the brains white matter, lung function, an increase in BP by mid-life.

Question 15

what links did the swedish conscript study make between low IQ and mental health?

Answer 15

• 60% increased risk of schizophrenia
• 75% increase of personality disorders
• 75% increase of alcohol related disorders
• 85% increase of substance disorders

Question 16

what was the swedish conscript study instrumental at showing?

Answer 16

the link between mental illness and intelligence as well as physical health and death

Question 17

what did the swedish conscript study do and what did it show us about physical health?

Answer 17

• tested 1.3 million non-adopted men and followed them up 19 years later.
• FOUND THAT a 1SD disadv of IQ increased the risk of death from all causes by 32%.
  a 51% increase in the risk of being murdered.
  1SD higher intelligence decreased the risk of stomach and skin cancer by 18% but no other links to cancer.

Question 18

what did the 1958 cohort interestingly show?

Answer 18

a link between childhood IQ and the health of the next generation.
women who smoked during pregnancy were a mean of 5.3 IQ points lower than those who did not
also found a link between IQ at the age of 11 and all cause mortality up to age 46

Question 19

how was the national survey of health and development 1946 conduced?

Answer 19

all children born within one week in march 1946.

5 waves of data collection - intelligence at age 8, health and illness, health behaviours etc.

Question 20

the 1970 cohort did follow ups until 2004. what was found about the link between intelligence and health behaviours?

Answer 20

those with higher IQ more likely to:

• eat more veg and wholesome foods
• exercise regularly
• less likely to eat unhealthy
• 16% less likely to smoke or be overweight

Question 21

what can explain the findings from 1945, 1958 and 1970 cohorts about mental illness?

Answer 21

• lower intelligence acts as a marker for impaired neurodevelopment which may influence mental illness
• higher IQ individuals are less likely to experience socioeconomic disadvantage and its concomitant stresses
• evolutionary psychology suggests that higher IQ is linked with a more efficient way of dealing with stress

Question 22

what needs to be looked at in future research?

Answer 22

• twin and adoption studies, genetic sequencing and early life intelligence and health data.
• the inclusion of women and non-white ethnic groups.

Question 23

what is still unclear about the link between intelligence, health illness and death?

Answer 23

• whether hte impact of intelligence on these factors is mediated by health behaviours or risk factors
• the exact role of education, income and social class.