(2011) Nature 477, 132, doi:10.1038/477132a Published online 07 Sep
Research to combat diseases, one would think, would be funded in proportion to the burden inflicted on the population. The reality is very different — witness the disparity between the huge burden caused by diseases in the developing world and the scant resources for research to tackle them.
Another disparity exists, and it is universal: the significant burden of mental and neurological illnesses of the human brain compared with the small proportion of research funds available to understand and treat them. Unlike cardiovascular disease and cancer, in most cases the burdens of brain disorders tend to manifest themselves in disabilities and in effects on the lives of the people afflicted and their carers, rather than in early deaths. That makes the footprint of these conditions harder to quantify.
So it is particularly valuable that a group of brain specialists and statisticians has produced a new quantification of the burden of brain disorders across 30 European countries. Building on a previous study, they assessed more disorders, analysed the literature and consulted national experts to validate emerging perspectives. The result? A conservative estimate that, in a typical year, about 165 million people — 38% of the total population of these countries — will have a fully developed mental illness. (Wittchen et al 2011)
The shocking statistics don't end with prevalence. A good measure of disease burden is the disability-adjusted life year (DALY) — the person-years lost in a population owing to disability and shortened life. The authors establish brain disorders — both mental and neurological — as the greatest health burden on the population, comprising 23.4% of all DALYs among men and 30.1% for women.
Many more men than women have alcohol-use disorders, especially in Eastern Europe; for both dementia and unipolar depression, the ratios of women to men are around two to one. The reasons for these latter gender differences are not understood, although depression among women seems to arise especially during their child-bearing years. The estimated number of people affected by major depression in the 30 countries studied is 30 million — the single greatest burden of all human diseases.
One piece of good news that emerges from the study is that the prevalence of individual conditions, alcoholism apart, has not grown in the past five years. The truly bad news is that only one in two people with a mental condition has ever received any professional attention, and that only 10% receive “notionally adequate” treatment — and then only after much delay following initial contact with health professionals.
What does this mean for research? The message for funding is clear: priorities need to shift. In financial terms, European research on brain diseases is much less-well supported than research on cancer, information technology, agriculture and other areas (see http://go.nature.com/hr2jqp). The state of the science is such that it requires major investment in all aspects, from fundamental neuroscience to psychological therapies.
There are subtler messages too. Research should target not only those brain diseases in which the prevalence in ageing populations will inevitably increase, such as Alzheimer's, but also the brains of young people, both healthy and ill. Many mental disorders emerge or begin to develop in the first two decades of life. Our knowledge of the healthy adolescent brain — a stage of still-active neural development — is rudimentary. The tantalizing prospect of therapeutic or preventive psychological or pharmaceutical interventions at such ages needs to be pursued.
This will give rise to ethical quandaries — probabilistic labels of future psychiatric disorders and over-reliance on drugs are problematic. But understanding how neural circuits develop in the young, and how environmental and innate influences combine to disrupt them, is one of the most fascinating and difficult scientific challenges of our time. The new study re-emphasizes just how urgent it is.
This editorial refers to a recently published and comprehensive review of both the prevalence and the burden of mental health disorders in Europe. (Wittchens et al 2011)
This careful and scholarly review found that in any given year, 38% of Europeans are suffering from a diagnosed mental health disorder.