HBS107 Lecture Notes - Lecture 8: Asthma, Food Safety, Cystic Fibrosis
HBS107 Week Eight
BIOLOGICAL DETERMINANTS OF HEALTH
The social structures and conditions in which people live and work affect health. The WHO
(1998, p.6) tells us that:
The determinants of health include the range of personal (biological and behavioural), social,
economic, and environmental factors that influence health status of individuals or
populations.
The biological determinants of health, including genetics, body functioning and body
structure. The NSW Health )2010, p. 16) defines the biological determinants of health as:
Biological, physiological, somatic, cellular, molecular, organic and genetic affects or
characteristics of the body that directly and measurably influence health.
CLASSIFYING THE BIOLOGICAL DETERMINANTS OF HEALTH:
The table below from NSW Health (2010, p. 19 gives you an overview of classifying
biological determinants of health into three different subclasses - genetics, body structure,
and body functioning - and various further subclasses in each category:
Biological determinants are strongly associated with particular health conditions (NSW
Health 2010, p. 16).
BIOLOGICAL DETERMINANTS AS 'RISK FACTORS' FOR DISEASE OR CONDITIONS:
Risk factors are variables that potentially increase the susceptibility of a person developing a
condition or disease For example, we know that physical inactivity and social isolation are
risk factors for CVD; interpersonal violence is a risk factor for depression; exposure to some
chemicals is a risk factor for cancer.
EXAMPLES OF THIS:
1. Aging = a risk factor for many conditions
• A biological determinant of health that is a potent risk factor for increased
morbidity (death) and mortality (disease) is aging. Age-related degeneration is
universally inevitable - we are all at risk! However, age-related degeneration can
be modified by attention to risk factors and environments.
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• Age = wear and tear minus repair
2. Genetics
• Another biological determinant of health that is a risk factor for disease is
genetics. We know that some people 'carry' specific genes that cause significant
illness - for example, breast cancer. The human genome project is constantly
making new discoveries about genes and gene patterns.
• Single gene conditions
o Single-gene disorders are characterised by how they are passed down in
families. The terms dominant and recessive describe the inheritance
patterns of certain traits. That is, they describe how likely it is for a
certain condition/disease to pass from parent to offspring. People with
one copy of a recessive disease gene are called carriers. Carriers usually
don't show the disease (NSW Health, 2010).
o Some single-gene conditions are more common in people with common
geographic ancestry; for example the gene for sickle-cell anaemia is more
common in families from Africa, India, Mediterranean countries, Saudi
Arabia, the Caribbean Islands, and South and Central America.
o Others such as haemophilia or Cystic Fibrosis, are found in people of all
ethnicities (and SES groups). For example, currently in Australia there are
around 3,000 people with haemophilia, a blood-clotting disorder which
can lead to excessive bleeding. A single-gene genetic alteration causing
haemophilia is passed down from parent to child through generations. It's
caused by a gene on the X-chromosome which means that men (who
have one X- chromosome and one Y-chromosome) with haemophilia will
pass the gene on to their daughters but not heir sons. Women (who have
two X-chromosomes) who carry the altered gene can pass it to their sons
or daughters. Sons with the gene will have haemophilia (as they have no
second X-chromosome without the haemophilia gene to 'override' it).
Some women and girls who carry the gene may also experience bleeding
problems.
• Chromosomal conditions
o The human species has 23 pairs of chromosomes, designated 1 to 22 in
order of decreasing size plus X or Y for the female and male sex
chromosomes respectively. However, some people have more or fewer
genes in a whole chromosome or chromosome segment, and this can lead
to chromosomal conditions such as Down's Syndrome, Klinefelter
Syndrome, and Turner Syndrome (NSW Health, 2010). However, it's
important not to pathologise people on the basis of their genetics - please
consider that some people with particular chromosomal conditions do
NOT characterise these conditions as a 'disease'.
• Multifactorial conditions
o Many of the most common diseases involve interactions of several genes,
other biological determinants of health, health behaviours and the
environment - for example, cancer, coronary heart disease,
hypertensions, and stroke.
CAN THE BIOLOGICAL DETERMINANTS OF HEALTH BE INFLUENCED?:
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Some causes of poor health are more proximate or immediate while others are more
distant (distal). The determinants of most interest to us in HBS107 are those amenable to
change through interventions - this includes the ways in which the biological determinants
of health can be modified to improve people's wellbeing.
NON-MODIFIABLE AND MODIFIABLE BIOLOGICAL DETERMINANTS OF HEALTH:
Genetically inherited diseases are non-modifiable but the experience of them and access to
treatment is related to the social determinants of health and can be modifiable. In fact,
almost all diseases or health conditions have some genetic component. However, the
importance of that component varies because multiple modifiable determinants/factors
interact with genes that are associated with diseases. For example, breast cancer.
Only some women with mutations in the BRCA1 or BRCA2 genes will go on to develop
breast cancer, which suggests the influence of factors other than biological (genetic) factors.
Studies have shown that women who have these genes but also smoke are at higher risk of
developing breast cancer than women who have the genes but don't smoke. Smoking, of
course, is modifiable (and a risk factor for many diseases, particularly heart disease).
INTERACTIONS BETWEEN BIOLOGICAL, ENVIRONMENTAL AND SOCIAL DETERMINANTS OF
HEALTH:
Biological factors frequently have contributing environmental and social factors which
combine to influence health status and health outcomes. This interaction between
determinants is important.
We know genes and environmental factors jointly influence health, but genetic influences
may play out differently under different conditions. Social determinants such as the social
gradient and education play a big role in how people experience similar conditions
differently. Chronic diseases including asthma, diabetes and Alzheimer's disease impose the
highest genetic 'burden of disease', mainly because of their higher prevalence in the
population. However, people with genetic predisposition to those conditions and who live in
poverty, have low education/literacy skills, poor housing and poor social support, will
experience a higher burden of illness.
Protective factors are conditions or qualities in individuals, families, communities, or wider
society that mitigate or eliminate risk and promote health and wellbeing. For example,
children who are nurtured generally do better across their lifespans than children who
experience neglect; people with good social support and who are involved with their
communities generally have better mental health than those who are socially isolated.
SUMMARY:
Some risks from biological determinants are modifiable, but others are non-modifiable.
However, people's experiences of these conditions can be ameliorated by access to good
care, social support, and particularly those who have economic resources (i.e. more wealth)
and better education will generally do better over time.
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Document Summary
The social structures and conditions in which people live and work affect health. The determinants of health include the range of personal (biological and behavioural), social, economic, and environmental factors that influence health status of individuals or populations. The biological determinants of health, including genetics, body functioning and body structure. The nsw health )2010, p. 16) defines the biological determinants of health as: The table below from nsw health (2010, p. 19 gives you an overview of classifying biological determinants of health into three different subclasses - genetics, body structure, and body functioning - and various further subclasses in each category: Biological determinants are strongly associated with particular health conditions (nsw. Biological determinants as "risk factors" for disease or conditions: Examples of this: aging = a risk factor for many conditions, a biological determinant of health that is a potent risk factor for increased morbidity (death) and mortality (disease) is aging.
