Traumatic brain injury (TBI) is often described as a silent epidemic: those who have been affected by TBI know how devastating its effects can be, yet awareness, funding, and research progress all remain at desperately low levels. During March, 2010—brain injury awareness month in the USA—the Brain Injury Association of America is launching a national campaign of education and advocacy. Raising public and governmental awareness about how to reduce the risks of brain injury and minimise the subsequent damage and distress is clearly important, but more fundamental changes in research and funding are also essential if the epidemic of TBI is to be tackled effectively.

Globally, TBI is a leading cause of death and disability in children and young adults. More than 1·4 million people are estimated to sustain TBI each year in the USA, of whom 50 000 will die as a result of their injuries. The annual incidence of fatality or admission to hospital owing to TBI in Europe is estimated to be 235 per 100 000 population. Although most TBI is classed as mild, more than 2% of the US population are thought to have a disability caused by a TBI. Yet awareness among the public and even clinicians remains low, and no new treatment for TBI has been approved in the past 30 years. NIH funding for TBI research in 2010 is expected to be US$81 million, whereas that for Alzheimer’s disease, which has a similar prevalence in the USA, is $527 million.

Why is TBI lagging behind? Advances in TBI research of the type that would attract pharmaceutical investment are few and far between. The slow rate of research progress can be attributed largely to the heterogeneity of TBI and poor understanding of its pathology and prognosis, which mean that potential therapies are not always tested in the people most likely to benefit. After the primary closed, penetrating, or crush injury, patients can have various types of secondary injury, and the underlying damage can include subdural or epidural haematoma, subarachnoid haemorrhage, contusion, diffuse axonal injury, or any combination of these. Acute symptoms can also vary widely, not only with the type of injury and region of the brain affected but also with complicating factors such as drug use or other injuries. TBI is generally first assessed using the Glasgow coma scale, but this does not adequately reflect the complexity of an individual patient’s situation or their underlying pathology. Other barriers to progress in understanding TBI include heterogeneity in care between centres, and the fact that no one specialty has overall responsibility for these patients.

Collaborative efforts have begun to address some of these issues. For example, the International Mission on Prognosis and Clinical Trial Design in TBI (IMPACT) study group is investigating trial design and prognostic factors, and in spring 2010 an international collaboration is due to make recommendations about which common data elements should be collected in clinical TBI studies. Several trials of acute treatments for TBI are ongoing, and the Traumatic Brain Injury Model Systems (TBIMS) network coordinates collection of data on the long-term effects of TBI and its management in the USA.

But, despite such initiatives, progress remains slow and funding inadequate. Some areas of brain injury research remain particularly neglected: relatively few trials are looking at mild TBI, or at rehabilitation strategies to improve the lives of the millions of people who live with the effects of TBI. Little is known about the effects of TBI on the developing brain, the mechanisms and contributions of secondary injury, or the effects of genetics on prognosis. The links between the long-term effects of TBI and neurodegenerative diseases are also only just beginning to be appreciated. The need for effective interventions and care is particularly acute in developing countries, where motor car use is increasing: road traffic accidents, which are already a leading cause of TBI in many parts of the world, are expected to become the third largest cause of global disease burden by 2020.

Campaigns to educate the public about how to avoid and respond to brain injury are needed, but without much greater and broader support for research there will be a limit to how much the burden of TBI can be reduced. Until TBI research becomes a more attractive proposition for pharmaceutical companies, funding is likely to remain the responsibility of charities and governments, although in view of the growing role of road traffic accidents motor vehicle companies should also take greater financial responsibility. The neurologists, emergency physicians, intensive care specialists, neurosurgeons, psychologists, physiatrists, and other rehabilitation professionals who treat patients with TBI must also work together to ensure that TBI research makes the advances that are so badly needed. Without such support and collaboration, TBI is likely to remain a silent epidemic.