A Positive Outlook for Chronic Disease—and the Challenges Still Ahead

Rates of chronic disease have been rising for decades in the United States. But new treatments for obesity and a deeper understanding of the common pathways that underlie these diseases are shaping the trajectory for a healthier future. We spoke with Nancy J. Brown, MD, the Jean and David W. Wallace Dean of Yale School of Medicine and C.N.H. Long Professor of Internal Medicine, about how Yale School of Medicine (YSM) researchers and clinicians are advancing discovery, educating students, and breaking down silos to address and prevent chronic disease.

The prevalence of chronic disease is increasing for a lot of reasons. One is that 100 years ago, people died of infectious diseases. And so chronic diseases are in many ways the diseases related to longer life. But a big factor in recent years has been the growing prevalence of obesity, not just in the United States but in the world.

We now understand that there are common pathways underlying different chronic diseases, such as heart disease, cancer, and neurologic disease. YSM has always been focused on understanding mechanisms and basic pathways, and in that sense, it has not changed how we do research. What has changed is the interdisciplinary nature of our research. We're focused on bringing people together from different fields to understand chronic diseases.

Yes, and this is also part of the alignment work that we're doing with Yale New Haven Health System. We believe that every patient who seeks care should participate in research. We know that improves outcomes. It also speeds discovery. We have done this for years in cancer, for example, where patients enroll in clinical trials and have access to cutting-edge therapies. Our vision is that this should be true across all diseases.

Obesity underlies a lot of our chronic diseases, and what we're seeing is that GLP-1 receptor agonists have impacts on heart disease, on addiction, on all sorts of things. An important question is to what extent those impacts are related to weight loss versus the specific mechanisms of the drugs. As we better understand the mechanisms, that gives us the potential to develop additional therapies.

Interestingly, we now understand that hypertension arises from immune disease and inflammation, and that raises the prospect of preventing hypertension. I'm very excited about some of the longer-duration therapies because compliance—regularly taking medications—is still an issue in treating hypertension. We also have new ways to address the effects of high aldosterone levels in patients with resistant hypertension, and that's exciting as well.

What YSM does well is integrate understanding of mechanism with understanding of clinical presentation, and we're revising our pedagogy around small groups to make that more effective. The other thing that we're doing is increasing education on the science of nutrition and diet, specifically helping students to understand how diet affects health.

I think the hard work that lies ahead goes beyond medications, and it's in the area of prevention. We have obesity because calorie intake exceeds energy expenditure, and we have built environments that don't promote walking. We saw this during COVID when people stayed home and there was less preventive care. But those areas are also in some ways harder to address; we need science around them as well. It's not at the molecular level, but it must be just as rigorous, controlled, and with randomization. We have to think about the built environment and making it safe and convenient for people to walk, as well as looking at food deserts and how to make healthy food accessible to all populations.

Yes, that is essential and another way in which we're breaking down silos. Collaborations with policymakers and with our colleagues in engineering and with the School of Public Health are critical to that.