Lifestyle & Disease - Lifestyle and Disease: Cause and Correlation (GCSE Biology)

Lifestyle and Disease: Cause and Correlation

Causal Mechanism

A causal mechanism has been proven for some risk factors, but not in others.

• A causal mechanism means there is a link between two factors. When a mechanism is causal, a change in one factor directly leads to a change in another. Therefore, a correlation is seen between the two and it is explained by the causal relationship between both factors.
• A correlation does not always prove causation. Just because it looks on a graph as though one factor is influencing the other, it does not always mean that there is a causation, there may be other factors in play.

• Most diseases are caused by a combination of factors. When you combine many of the risk factors, their effects can be amplified. For example, if you drink, smoke and do not exercise, you have an even greater risk of cardiovascular disease.

Examples of Risk Factors

Some lifestyle choices can be a cause for disease. They have already been discussed in detail (refer to previous chapters) but below is a summary of some known causal relationships:

• Diet, smoking and exercise have a causal relationship with cardiovascular disease
• Obesity has a causal relationship with Type 2 Diabetes.
• Alcohol affects liver and brain function.
• Smoking can increase the risk of lung disease and cancer.
• Smoking and alcohol can affect unborn babies.
• Carcinogens are risk factors for cancer. Certain factors predispose a person to cancer, these are called carcinogens. Examples include ionising radiation, smoking and viral infections. Some laboratory workers have to wear radiation detectors, to ensure that they do not get too much exposure to radiation (which could lead to a high cancer risk).

Sampling

• Samples can be used to assess the risk factors in a population. The general principles of sampling of taking a random, large, unbiased sample must be used when looking into a sample of people with risk factors.
• Risk factors can be plotted on graphs and in tables. Read the data in these tables and see if there is a link. On a graph, if there is a link, there is a correlation. This will be shown as you can draw a straight line through the data.

• Here you can see that a line can be drawn through the points to show a correlation.