Mar 172011

Birth cohort epidemiology is considerably more exciting than this film

In recent times, science has been portrayed as sexy and exciting. From Professor Brian Cox’s Wonders of the Solar System/Universe to Hans Rosling’s attempts to convince us that statistics are sexy. And you know something? They’re right.

Exciting demonstrations of the joy of science can lead us to forget just how much time, dedication and in many cases, tedium is required to develop an understanding of the reality in which we live. Much of science, and even academia as a whole, is a case of iteratively updating our existing understanding through slight modifications of experiments and theories that have gone before, and the groundbreaking, “Eureka!” moments are few and far between, reserved for the exceptionally insightful, the fantastically lucky, and most importantly those who are able to make those ideas heard.

But we should celebrate those who conduct their research with the long haul in mind; after all, we stand not so much on the shoulders of giants, as on a tapestry of the endeavour of hundreds, thousands, millions of people all contributing their bit to society and understanding. One of the noblest aims is surely to be one of those strands, a fibre on which future generations will rest their feet as they reach that little bit higher in pursuit of knowledge than the generation before.

In health research, you can’t get much more long term oriented than epidemiology. Epidemiologists study (usually very large) groups (or cohorts) of people over time, often for years. One good example is the Whitehall study, which from 1967 followed a cohort of 18,000 men in the British civil service over the course of 10 years. A whole host of background information was recorded, such as social class, smoking status, available leisure time, and importantly if they died – when this occurred. The study is most famous for establishing the link between social class (judged by the grade of their employment, denoting the ‘status’ and income associated with their job) and mortality – people of lower social class died earlier, even after controlling for a raft of the most obvious associated risk factors such as smoking status, physical activity and diet. For example, the lowest class were 3.6 times more likely to die of cornonay causes than those in the highest. This has become known as the ‘social gradient’, and is now one of the key issues in medicine and public health in countries with a socialised healthcare system; just because a health service is free to all patients, this does not mean that wealth and social status does not affect the quality of health people can expect. Trying to understand why, and to improve outcomes for those currently worst off, is now a highly salient area of research.

Another excellent example is the 1946 Birth Cohort study. This, to me, is where it gets really sexy – in a very slow, methodical and unbelievably patient way. Normally as health researchers, when we devise a study we expect to have results that we can generalise to large populations of people within months or a few years. We take cross sections of people – if we want to know about children, we recruit children. If we want adults with renal disease, we recruit people with renal disease. In epidemiology though, we want to see what happens, prospectively, over time – to a whole range of people. We want to see who does well at school, or who gets sick; and we want to base it on good, prospective data, rather than asking people questions years later (e.g. “What were you like as a child”, to someone who has later become successful – as their present success may influence their recollection of the past).

The 1946 birth cohort study happens at the speed of human life. This fantastic article from the prominent journal Nature does a good job of reflecting on the enormity of 65 years of research – as the participants themselves have just turned 65. We’ve discovered a lot from the results so far, about the social gradient, about predictors of success, and beautifully (as described in the article by the study’s current head, Diana Kuh) that it appears that while our genes and backgrounds are significantly predictive of many things in life, there is always scope for individual agency and change over the course of the lifespan.

And the cohort is still going. As they enter old age, the ongoing stream of incoming data will be as important, if not moreso, than ever. With an ageing population, understanding what causes people to remain healthy, happy and functional in old age is more important than ever. With this study, we can look at the relationships between things that happened from the day these people were born with things that are happening to them now.

The article also presents the cohort from a wonderfully humanist perspective; that these are people who should be cooperatively included in research and treated with respect for their contribution to science. It’s well worth a read.

And so while it’s always tempting to think of modern science as something fast moving, dynamic and (according to the tabloid media) a place where every day brings world changing breakthroughs, let’s spare a thought for those playing the long game, advancing our understanding of the course of a human life from a scientific perspective; one year at a time.