Modern medicine has provided us with a cruel paradox: Because of major medical advances, we are living longer than ever, but our ability to prevent and treat the chronic diseases that afflict us in our final years has not kept pace.

Nowhere is this paradox more evident than in Alzheimer’s disease. Alzheimer’s and other forms of dementia are rapidly becoming a global crisis, as populations around the world age in greater numbers. The cost to the global economy was estimated at more than $600 billion in 2010, an amazing 1 percent of global economic activity. And new figures released last month indicate that the burden may be greater than previously thought, with prevalence expected to roughly triple to 135 million cases by 2050, putting an enormous strain on health care systems worldwide.

Alzheimer’s is a slow, incurable brain disease that ultimately robs one of one’s mind. There is an urgent need for treatments to slow or stop this brain deterioration, but no such treatment has been found despite many high-profile attempts. It’s become clear that this is a global problem that will require a global solution.

For the first time, international leaders from the G-8 countries came together last month at a dementia summit in London and embraced a goal previously set by the United States to develop a disease-modifying therapy for dementia by 2025. What’s more, they committed to creating a global envoy for dementia innovation to coordinate international efforts, a critical step toward addressing the real challenges impeding Alzheimer’s drug development.

Traditionally, we’ve depended on the competitive engine of the pharmaceutical industry, backed by government-funded basic research, to bring the therapies we need to market. But Alzheimer’s is not a typical disease. A new report and analysis, commissioned for the first Alzheimer’s Disease Summit, shows that the costs and risks of developing an Alzheimer’s drug are dramatically higher than for other diseases — three times the industry average.

Alzheimer’s drug development is often inefficient and riddled with bottlenecks. A single phase III study can require years to enroll participants, let alone return a verdict on the therapy. What’s more, researchers and companies don’t have consistent yardsticks for determining what makes a promising drug in the first place.

Setbacks are to be expected in research, but they have occurred at a far higher rate and price for Alzheimer’s than for other diseases. Fortunately, there are lessons that can be borrowed from fields where research progress has been more rapid, such as HIV and AIDS, heart disease and cancer, and a number of practical reforms could speed Alzheimer’s drug development.

One common theme is the need for greater and more strategic cooperation. Today, it’s widely recognized that solving challenges in Alzheimer’s research and drug development will require a shift from independent efforts to a collaborative system. Companies must continue to expand their efforts to share data with competitors — especially negative data, which often provide crucial clues for the next attempt — much like was done in HIV and AIDS research.

It’s also critical that we make clinical trial systems open and coordinated on an international scale. We can do this by establishing large cohorts of potential trial participants so trials can be started and completed faster and so participants can be better matched to the interventions most likely to benefit them. Finding and sharing reliable biological markers that measure the disease’s progress, with or without any symptoms, would provide an earlier understanding of which drugs work, ultimately speeding progress.

If companies, governments and academic researchers make these changes, we can get back on track to developing a drug that can slow or reverse Alzheimer’s by 2025 — and offer tremendous benefits for patients and health systems. We could avert 7 million case-years of dementia and save upward of $100 billion in health care expenditures over a 15-year period, according to the Alzheimer’s Disease Summit report.

The G-8 has recognized the urgency of responding to the growing crisis of Alzheimer’s disease and other forms of dementia. Now, we all must stand behind its commitment and do our part to streamline drug development so that we can make the 2025 goal a reality. We need new Alzheimer’s drugs sooner, so our health span can equal our lifespan.

Ellis Rubinstein is president and CEO of the New York Academy of Sciences; George Vradenburg is the convener of The Global CEO Initiative on Alzheimer’s Disease.