Relationship between depression and other health conditions

Andrew J. Cutler, Ph.D:Sagar, can we talk a little bit about the interaction between depression and other health conditions, medical and otherwise?

Sagar V. Parikh, Ph.D., FRCPC: Well, we know that depression itself is a heterogeneous disease. There is no single etiology. In part, there may be a subset of people, perhaps a very large subset of people, who have inflammation at their core. If we look just from an epidemiological perspective, of course, depression and heart disease, depression and diabetes, depression and many other chronic diseases have much higher rates of comorbidity than you would expect. Is this just a functional consequence of altered depressive behavior? If you are depressed, you become couch potato and then your cardiovascular fitness erodes. Well, yes, of course. That’s part of it, but maybe it’s that they share some elements of a common etiology, maybe neuroinflammatory, maybe something else, that leads to higher rates of depression and higher rates of other diseases. We know that insulin secretion and resistance are factors not only common to diabetes, but also very common in mood disorders. It is likely that there is a shared mechanism that drives the interaction between depression and other medical disorders.

Andrew J. Cutler, MD: It’s really fascinating this two-way relationship, isn’t it? There is more depression if you have diabetes, more diabetes if you have depression, and so on. Greg, let’s also talk about the economic impact of MDD. Give us some insight into what the larger economic impact of MDD is, and particularly of untreated or inadequately treated MDD.

Gregory Mattingly, Ph.D: Of course. This is the good news and the bad news about this disease. The bad news is that depression is one of the leading causes of disability now worldwide. Here in the United States, it is one of the leading causes of disability in adults. We’ve seen disability rates with depression go up over the last decade, so while we’re winning the battle with many of our diseases like cardiovascular disease and various cancers, disability rates with depression have gotten worse over the last decade. The good news is that there are countries around the world, including our country, the United States as a whole, that are increasingly focusing on mental health. They know that mental health is a major driver of well-being in our society with a more holistic treatment of depression considering this mind-body connection. Why does depression interact with things like diabetes, chronic pain, insomnia, and inflammation? So how do we help move the needle holistically for our patients? It’s getting more and more research and more and more emphasis. Employers are starting to look at it. They say, listen, if this is one of the leading causes of disability in my workforce, not just disability, but when they show up to work, they don’t accomplish as much if they’re depressed. This term that we talked about, Andy, is called presenteeism. I show up for work but only get paid 70% of what I would get if I was healthy and doing well. This is attracting increasing attention from employers, our federal government, and various research organizations.

Andrew Cutler, MD: Greg, I think you’ve put your finger on something very important, and that is that while we focus on the symptoms of depression, and those are very important, we also need to look at the bigger picture. We need to look at health, quality of life, functioning and whether the person feels like themselves. This of course includes productivity and this leads to an economic impact. Sagar, there are some really big costs associated with depression, both direct and indirect. Can you tell us a little bit about that?

Sagar V Parikh, MD, FRCPC: I think Greg hinted at this. We can think of total cost as really a function of 2 things. There are the direct costs of treatment and all the costs associated with premature mortality and, of course, absenteeism. Quite surprisingly, the direct costs of treating depression are only a small fraction between 10% and 20% of the total costs associated with depression. The economic literature addressing this also confirms that this is a fairly universal phenomenon across countries. It’s not just segmented into a few countries. It is also true even in the developing world, where economic losses due to absenteeism or absenteeism far exceed the direct costs of treatment. They are massive. I think one of the comforting things is that the models we have for providing treatment right now are, “Oh, you’re sick. Come to my office and I’ll treat you. It’s not really that scalable. I’m really excited to see a variety of other treatment models that say we need to have a public health approach to treating depression. Can we use digital tools? Can we use websites to provide some elements of care? Can we do things in our schools? Employers actually offer much better employee assistance programs than they did a decade ago. Some of it is preventative like wellness, as you mentioned Andrew, but also some is actually resources, whether it’s digital tools or more focused types of treatments for workers. Sometimes workers receive treatment at their workplace. Again, this is much more scalable to address the problem where it is, and much more appropriate given the enormous cost of these disorders.

Andrew J. Cutler, MD: We are not just talking about innovative new drugs, but really about treatment models, treatment systems. I guess one thing that COVID-19 has taught us is how to use telemedicine, which can also expand our reach. Greg, who does most of the MDD screening and diagnosis out there?

Gregory Mattingly, Ph.D: They are not psychiatrists. First we are not enough, but now we know that this is a condition of the community. Depression makes no difference. It lives among us. We have probably all had a friend, family member or loved one who has been affected by depression. Now we see that most of the screening, most of the prevention of depression and the earlier dimensions are done in the primary care arena. It could be your family doctor, it could be an internist, or it could be a nurse practitioner who works at one of your community clinics. Many of our new screening systems, Sagar said, plug right into your electronic medical record. Screening each patient with the PHQ-2 [patient health questionnaire-2]. Have you had problems with depression? Have you had problems with anhedonia? Have you had issues where your mood isn’t what it should be? It’s a screening tool that’s built right into it and is considered a measure of quality for most of our primary care physicians.

Transcript edited for clarity

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