Download Lecture 2 - Andrew J. Oswald

Mental Health and Biomarkers
Andrew Oswald
IZA and Warwick
Now let’s broaden the idea of
human well-being (beyond
‘happiness’).
We’ll discuss biomarkers
We’ll discuss biomarkers
Heart rate
Systolic blood pressure
Diastolic blood pressure
C-reactive protein
Fibrinogen
But let’s start with mental
health.
I will say almost nothing about
really serious mental illness.
I will say almost nothing about
really serious mental illness.
Psychosis occurs in about 1% of
the population.
Instead we can think of mental illhealth (depression, anxiety, and
mental strain).
Happiness and life-satisfaction
equations typically have similar
structures to mental-health
equations.
A psychological-ill-health measure
used a lot in the psychiatry
literature is a GHQ score (which
stands for General Health
Questionnaire).
Typical GHQ mental-strain
questions
Have you:
Lost much sleep over worry?
Typical GHQ mental-strain
questions
Have you:
Lost much sleep over worry?
Felt constantly under strain?
Typical GHQ mental-strain
questions
Have you:
Lost much sleep over worry?
Felt constantly under strain?
Felt you could not overcome your difficulties?
Typical GHQ mental-strain
questions
Have you:
Lost much sleep over worry?
Felt constantly under strain?
Felt you could not overcome your difficulties?
Been feeling unhappy and depressed?
It was developed as a way to judge
who needs psychiatric treatment.
The exact 12 questions that
make up a GHQ score
“Have you lost much sleep over
worry?”; “Been able to concentrate on
things?”; “Felt you are playing a useful
part in things?”; “Felt capable of
making decisions about things?”; “Felt
constantly under strain?”; “Felt you
could not overcome your difficulties?”;
“Been able to enjoy your normal day-today activities”; “Been able to face up to
your problems”; “Been feeling unhappy
and depressed?”; “Been losing
confidence in yourself?”; “Been
thinking of yourself as a worthless
person?”; “Been feeling reasonably
happy all things considered?”.
Each of the 12 questions is scored
out of 3.
On a 36-point scale
Mean of GHQ
Standard deviation
10.4975
4.89
You will remember:
The pattern of a typical person’s
happiness through life
Average life satisfaction score
5.6
5.5
5.4
5.3
5.2
5.1
5.0
4.9
15-20
21-30
31-40
41-50
Age group
51-60
61-70
This holds in various settings
This holds in various settings
For example, we see the same
age pattern in mental health
among a recent sample of
800,000 UK citizens:
[Blanchflower and Oswald, Social Science & Medicine, 2008]
The probability of depression by age
Males, LFS data set 2004-2006
0.02
Regression coefficient
0.015
0.01
0.005
0
-0.005
-0.01
1938
1942
1946
1950
1954
1958
1962
1966
Year of birth
1970
1974 1978
1982
1986
1990
Depression by age among females: LFS data
2004-2006Q2
0.002
Regression coefficient
0
-0.002
-0.004
-0.006
-0.008
-0.01
-0.012
-0.014
1942
1946
1950
1954
1958
1962
1966
Year of birth
1970
1974
1978
1982
1986
1990
An important border is between
happiness and medicine
An important border is between
happiness and medicine
•
Is it possible that we could find
physiological correlates with human
well-being?
•
Perhaps to broaden the standard
policy goal of GDP?
We are studying mental well-being
and physiological data on a
random sample of 100,000 English
citizens.
We are interested in equations for
We are interested in equations for
Heart rate
Systolic blood pressure
Diastolic blood pressure
C-reactive protein
Fibrinogen
Blood pressure = cardiac output
X peripheral resistance.
Systolic pressure is the force of
blood in the arteries as the heart
beats. It is shown as the top
number in a blood pressure
reading. High blood pressure is
140 and higher for systolic
pressure.
Diastolic pressure is the force of
blood in the arteries as the heart
relaxes between beats. It's shown
as the bottom number in a blood
pressure reading.
C-reactive protein (CRP) is a protein
found in the blood, the levels of which
rise in response to inflammation (i.e. Creactive protein is an acute-phase
protein). It is synthesized in the liver.
Fibrinogen is a protein that plays a key
role in blood clotting. Fibrinogen is a
sticky, fibrous coagulant in the blood
that increases the risk of experiencing
one of the leading causes of death and
disability - stroke.
Why would we care?
It is known that heart rate
rises under stress.
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
Stress comes in different forms
• Nicolas Troubat et al (2009)
European Journal of Applied
Physiology
20 chess players – international
and national-level players. They all
played against a computer.
The computer standard was
deliberately set one level
higher.
The computer standard was
deliberately set one level
higher.
So all the players lost against
the computer.
What happened?
• Average heart-rate rose 11 beats a
minute
• On average, players used up 140
calories playing the game
• Overall, the physiological changes
were “similar…those … in
moderate physical exercise”.
Question
Could physiological
measures -- biomarkers -- be
used as proxies for wellbeing?
Good time for points or questions?
Or maybe in the long run in
western society we can blend wellbeing survey responses with
biomarker data.
For example
Cortisol is produced by the adrenal
gland in the zona fasciculata, the
second of three layers comprising the
outer adrenal cortex. This release is
controlled by the hypothalamus, a part
of the brain.
Main functions of cortisol in the body
• increasing blood sugar through
glycogenolysis and reduction of
glucose uptake into cells.
• suppressing the immune system
• aiding in fat, protein, and carbohydrate
metabolism
The amount of cortisol present in the
blood undergoes diurnal variation; the
level peaks in the early morning
(approximately 8 am) and reaches its
lowest level at about midnight-4 am, or
three to five hours after the onset of
sleep.
Important work by Andrew
Steptoe of UCL:
Whitehall II data
Salivary cortisol (Steptoe data)
10
P = .009
nmol/l
9
8
7
6
5
1 Low
2
3
Happiness quintiles
4
8 samples (08:00 – 22:30)
Adjusted for gender, age, occupational grade, smoking, bmi, and GHQ
5 High
Heart rate
Men
Women
P = .017 in men
80
bpm
76
72
68
64
1 Low
2
3
4
5 High
Happiness quintiles
Adjusted for age, occupational grade, concurrent
physical activity, smoking, bmi, and GHQ score
Steptoe et al, 2005
PNAS
Some of our latest work:
Joint with Nicholas Christakis (Harvard) and
David Blanchflower (Dartmouth)
Statistical links between the
heart and income and
happiness.
Pulse: Average heart rate is
about 72 beats per minute.
Interesting patterns emerge
• First, there are well-determined
income gradients in (and only
in) heart-rate and C-reactive
protein equations.
• Second, heart rate seems to
have potential as a proxy
measure for mental strain, so
might eventually be usable as a
measure of negative ‘utility’ in
an economist’s framework.
• Third, education has little effect
within biomarker equations.
• Fourth, it is more important to
control for diet than has been
traditionally recognized in the
health-economics literature.
• Fifth, biomarker variables work
powerfully in well-being
equations.
To clinicians
High blood pressure is
potentially a sign of mental
strain and low well-being
But how about high blood
pressure as a national
measure of well-being?
Percentage of citizens very satisfied with their lives
Across nations, hypertension and
happiness are inversely correlated
(Blanchflower and Oswald, 2008 Journal of Health Economics)
Figure 2.
The Inverse Correlation Between Hypertension and Life
Satisfaction: 16 European Nations Aggregated into Quartiles
Percentage of citizens very satisfied with their lives
50
40
30
Ireland
Denmark
N'Lands
Sweden
Spain
France
Lux
UK
20
10
Austria
Italy
Belgium
Greece
E. Germany
W. Germany
Portugal
Finland
0
Countries in the
lowest quartile
of blood-pressure
Countries in the
highest quartile
of blood-pressure
Happiness and mental wellbeing are of interest in
themselves.
But, more broadly, there seem
to be deep links between mind
and body.
Author(s): Ebrecht M, Hextall J, Kirtley
LG, Taylor A, Dyson M, Weinman J
PSYCHONEUROENDOCRINOLOGY
Volume: 29 Issue: 6 Pages: 798809 Published: JUL 2004
“Every subject received a standard
4mm-punch biopsy, and the
healing progress was monitored
via high-resolution ultrasound
scanning.”
“Every subject received a standard
4mm-punch biopsy, and the
healing progress was monitored
via high-resolution ultrasound
scanning.”
Ebrecht et al 2004
• The overall results showed a
significant negative correlation
between speed of wound healing
and GHQ scores (r = -.59; p < .01)
In other words, happier human
beings heal more quickly.
A more recent paper
A more recent paper
“Enhanced wound healing after
emotional disclosure intervention”
Weinman, Ebrecht et al
BRITISH JOURNAL OF HEALTH
PSYCHOLOGY Volume: 13 Pages:
95-102 Part: Part 1 Published: FEB
2008
• Participants who wrote about
traumatic events had significantly
smaller wounds 14 and 21 days
after the biopsy compared with
those who wrote about time
management.
Also
There is some evidence that
happiness seems to make you
live longer.
The ‘Nuns Study’
Journal of Personality and Social
Psychology, 2001
“Positive emotions in early life and
longevity: Findings from the nun
study.” By Danner, Deborah D.;
Snowdon, David A.; Friesen, Wallace V.
Journal of Personality and Social
Psychology, Vol 80(5), May 2001, 804813.
• Handwritten autobiographies from 180
Catholic nuns, composed when
participants were a mean age of 22
years, were scored for emotional
content and related to survival during
ages 75 to 95.
One of the nuns wrote:
“God started my life off well by bestowing
upon me grace of inestimable value… The
past year which I spent as a candidate
studying at Notre Dame has been a very
happy one. Now I look forward with eager
joy to receiving the Holy Habit of Our Lady
and to a life of union with Love Divine”
Whilst another nun wrote:
“I was born on September 26, 1909, the
eldest of seven children, five girls and two
boys… My candidate year was spent in
the motherhouse, teaching chemistry and
second year Latin at Notre Dame Institute.
With God’s grace, I intend to do my best
for our Order, for the spread of religion
and for my personal sanctification.”
• After joining the order their lives were
almost exactly the same - same food,
same work, same routine
• But not the same life expectancy…
• Among the less-positive nuns, 65%
died before their 85th birthday. Among
the happy nuns, 90% were still alive.
• A strong inverse association was found
between positive emotional content in
these writings and risk of mortality in
late life (p < .001).
• As the quartile ranking of positive
emotion in early life increased, there
was a stepwise decrease in risk of
mortality resulting in a 2.5-fold
difference between the lowest and
highest quartiles.
• Positive emotional content in early-life
autobiographies was strongly
associated with longevity 6 decades
later.
An early, famous paper
• Title: PSYCHOLOGICAL STRESS AND
SUSCEPTIBILITY TO THE COMMON COLD
Author(s): COHEN S, TYRRELL DAJ, SMITH
AP
Source: NEW ENGLAND JOURNAL OF
MEDICINE Volume: 325 Issue: 9 Pages: 606612 Published: AUG 29 1991
Researchers need to
understand these mind-body
interconnections better.
• Another interesting issue is how
we might match (or validate) wellbeing data with measures of
mental health.
Consider the famous U shape in
well-being through life.
Say a sceptic disbelieved all wellbeing data and just would not
change his or her mind.
One route would be to use data that
independently confirm the patterns
in happiness regression equations.
One route would be to use data that
independently confirm the patterns
in happiness regression equations.
Here is an example.
Antidepressants
Work joint with Blanchflower on
antidepressant consumption in Europe.
Proportion of Europeans taking antidepressants
(regression-adjusted) through life
0.12
0.1
0.08
0.06
0.04
0.02
0
15
25
35
45
55
-0.02
-0.04
-0.06
Age
65
75
85
What about causality?
Forthcoming paper by Nick Powdthavee
(in the Journal of Human Capital)
Nick Powdthavee’s work on blood
pressure and education
The drop in hypertension
His regression equations
Results for males
Results for females
Some conclusions today
#1
Mixed evidence on ‘education
gradients’ in heart biomarker
equations.
#2
A variable for the consumption
of fruit and vegetables works
strongly.
#3
After we control for fruit and
vegetables, income plays a
clear role only in heart-rate and
C-reactive protein equations...
#3
After we control for fruit and
vegetables, income plays a
clear role only in heart-rate and
C-reactive protein equations...
and the income gradient looks
small.
Heart Rate (Page 24 of Blanchflower et al)
Could you go back to the
Blanchflower et al biomarkers
paper (hard copy).