Why am I fat? Cohort studies, Biobank, and the future of genetics research
In another seemingly obvious medical breakthrough, the EarlyBird Diabetes trust has found that its not how much exercise you do, but what you eat that makes you fat as a child. But how do you go about proving something like this?
Ground breaking genetic research suggests this young child has a desire to go into a career in the health sciences. Who gave him the scalpel?
It sounds obvious, but it puts advice into perspective that its lack of exercise that is the most important factor in childhood obesity. With the alarming rise in obesity in Western Europe and North America, and the failure of recent pharmacological therapy to provide an answer in adults (sibutramine whipped off the market by teh European medicines agency in the UK because of the cardiovascular risk profile: myocardial infarctions and stroke disease), the evidence now suggests we should be switching the three times a week exercise regimes for our children to three times as less packets of crisps in the lunch boxes.But where do these findings come from, can we trust them, and how do you go about finding out these things?
The answer is in a cohort study. A cohort study is a study where you follow up a group of people who may not have a disease (in this case obesity, but it could be anything, multiple sclerosis, rheumatoid arthritis, motor neuron disease) over time (longitudinal) and see what happens to them. This way you can look at all sorts of factors, and see how they appear to influence other outcomes (obesity , depression, getting a job).
Lets take a look at some of the key findings of this cohort study:
Children’s activity not determined by environmental opportunity- Green spaces and sports centres do not influence the physical activity of children
Like most things biological, a child’s activity level seems to be ‘set’
by the brain, and therefore strongly defended against change
These things may seem common sense, but someone needs to go out and prove it.
Healthy weight for life? Start at birth. Most excess weight (90% in girls) is gained before the child ever starts school
That’s more like it. Its because this is a well designed cohort study that this question can be answered. They didn’t go back and look at the records of obese children and compare them to children of normal weight (a case control study), and there are obvious advantages in the (often expensive) cohort design.
So where do we go from here with genetics, and our long term health? Well good medical research is all about how you go about answering these difficult questions that life poses.
Only a few days ago in the news more evidence (from the journal Neurology) from a cohort study of patients with depression suggests the following. Again this is more cohort study data. More info here.
Depression is associated with an increased risk of dementia and AD in older men and women over 17 years of follow-up.
The largest longitudinal genetics study of its kind has just finished recruiting in the UK. Visit their homepage.
What this is showing is the potential power of a well designed cohort study: groups of children followed up over time with data collected on their health, allowing comparisons between the children in the cohort, or other patients. Its more cohort studies like these that will hopefully provide the answer to a number of the outstanding genetics questions that are being posed at present. The UK Biobank study is the largest of its kind in the UK has just finished recruiting. Find out a little more from this excellent BBC coverage of the project in the video below.
Finally lets have some views from the students. Suppose we need to know more about a what causes a rare form of myositis (e.g. 1 in 1 000,000)/ or haematological cancer? What’s the best approach to designing a study to look into this. Would a cohort study like these do the job?And what about the consent for the Biobank project. Can people ever really know what they are letting themselves in for? More questions, we’ll have to wait for the answers. Comments please…
Like most things biological, a child’s activity level seems to be ‘set’
by the brain, and therefore strongly defended against change