Disease lobby groups have always made energetic efforts to ensure that the formidable resources of the US National Institutes of Health (NIH) are brought to bear on the health issues that interest them; and that is as it should be. When these resources are expanding, there has been room for most of the participants in the process to feel that they are winning. Now that the budget of the largest research agency in the world is effectively frozen, there are likely to be more losers.

In the case of research into autism — a common but poorly understood developmental disorder — effective advocacy has seen a generous increase in NIH support specifically targeted at the disease, even since the real growth in the agency's total budget came to an end in 2003. Unfortunately, some of autism's success may have come at the expense of research into other children's diseases (see page 628).

Autism research also garners an unusually strong level of support from private sources, including funds raised by the disease group Autism Speaks and contributed by philanthropists such as Jim Simons, a mathematician and hedge-fund billionaire whose daughter suffers from the condition. This year, these sources will spend some $50 million — roughly half what the NIH is spending on autism research. Typically, disease groups can muster charitable funding that is only a small fraction of what the NIH spends (see Nature 447, 248–254; 2007). That leaves them scrambling for slices of a pie that is no longer growing.

Scientists, especially those involved in the basic biomedical sciences, are also scrabbling for a share of these funds. The NIH's success has been built on a tacit accommodation between scientists, who run its 27 institutes and centres on a day-to-day basis, and the public, as represented by Congress. Institutes have been established — often against the scientists' advice — to deal with specific conditions or diseases of particular organ systems. Then Congress has, in large part, left the researchers and physicians in the agencies to pursue their work as they see fit, without indulging in too much micromanagement.

This has enabled the NIH to maintain a formidable reputation for scientific integrity and excellence, while also appearing to be reasonably responsive to patient needs. It has produced an agency that does a great deal of basic scientific research — with unknown and largely serendipitous benefits for the development of drugs and devices — as well as plenty of laboratory and clinical work devoted to particular ailments.

The public is paying for the NIH's annual budget of $29 billion, and it is entirely appropriate that it should energetically articulate its demands of the agency. That is one of the roles of the disease-advocacy groups, and their input, as any NIH institute director will attest, provides invaluable assistance in assigning research directions and priorities.

The power of some advocacy groups must be tempered to some degree.

That said, the power of some advocacy groups must be tempered to some degree — especially in today's difficult funding environment. Otherwise, these groups' ability to influence budgets is likely to dominate, to the detriment of both basic laboratory science and of research targeted at diseases that have weaker constituencies.

It falls to the scientist-administrators who run the NIH to work closely with members of the congressional appropriations committees that fund the agency to make sure that this does not happen. Both groups understand the careful political balance that has allowed the agency to thrive; they must act as moderators whenever the more energetic lobby groups are pushing the agency's agenda too far in the direction of one public-health issue at the expense of others.