1.12 Know how factors such as genetics, diet, age, gender, high blood pressure, smoking and inactivity increase the risk of cardiovascular disease (CVD)
1.15 Be able to analyse and interpret quantitative data on illness and mortality rates to determine health risks, including distinguishing between correlation and causation and recognising conflicting evidence
1.16 Be able to evaluate the design of studies used to determine health risk factors, including sample selection and sample size used to collect data that is both valid and reliable
1.17 Understand why people’s perception of risks are often different from the actual risks, including underestimating and overestimating the risks due to diet and other lifestyle factors in the development of heart disease
- Risk = probability of occurrence of an event or outcome (usually negative)
- Divided into non-modifiable and modifiable
Non-modifiable risk factors
- Genetics – some people have inherited genes which make their arteries more easily damaged, increase tendency to develop hypertension or lead to problem with cholesterol balance
- Age – blood vessels lose elasticity with age and become more prone to damage
- Gender – oestrogen (a female hormone) reduces build-up of plaque and offers women some protection against CVDs until they reach menopause
Modifiable risk factors
- Diet – high intake of saturated fat and food with high cholesterol level
- Physical activity – exercise reduces risk of CVD by lowering blood pressure and increasing good cholesterol (HDL) levels
- Smoking – chemicals in cigarettes cause physical damage to artery linings and arterial constriction
- Cohort studies - follow a large number of period over a period of time and see if they develop the condition
- Case-control studies - divide into a group with the condition and a group without and identify factors by investigating in past history
- A good study should produce valid and reliable results
- Sample selection should not be biased but should be representative of the whole population
- Variables controlled as far as possible and measurement techniques should be standardized
- Adequate sample size
- The graph below shows that the incidence of chronic heart disease increases with blood cholesterol level, i.e. the incidence is correlated with blood cholesterol level. However, it cannot be concluded from the graph that high blood cholesterol causes CHD.
When one variable changes with another variable, two variable are correlated. To prove causation, further experiment is required to prove the mechanism by which one factor causes another.
Actual risk vs perceived risk
- People's perceived risk be higher or lower than the actual risk
- Can be affected by:
- People’s personal experience
- Inability to assess risks well
- Peer pressure
- The remoteness of the likely consequence
- Belief in fate and destiny
Fancy a run after studying?
1. Edexcel AS Biology Revision Guide. Edexcel.