Precision Psychiatry in the 21st Century: An Interview with Dr. Ronald Kessler

Interview by Sarosh Nagar

HHPR Editor Sarosh Nagar interviewed Ronald Kessler, Ph.D. He is the McNeil Family Professor of Health Care Policy at Harvard Medical School. Dr. Kessler is one of the most world’s most widely-cited researchers in the study of the epidemiology of mental illness. Read more about his work here: https://hcp.hms.harvard.edu/people/ronald-c-kessler.

Sarosh Nagar (SN): It is an honor to speak with you, Dr. Kessler, and it's an honor for us and our readers to be able to interview you as one of the world's most widely cited researchers in psychiatry. I want to get started with the question we ask all our interviewees: "What got you interested in psychiatry and mental health?

Ronald Kessler (RK): What got me interested in mental health? Well, this is why many moons ago, obviously. So I was originally interested in criminology as an undergraduate and then went to graduate school in sociology, where I studied criminology. And that was at the beginning of the drug epidemic in the late early 70s, and I got interested because everybody was working in criminology, especially on drugs, and I started getting interested in adolescent drug use. So I got a job working at a research group that was doing this big study of adolescent drug use and was looking at the effects of family factors, friendship factors, and social networks.

But there was also an issue about self-medication in the study, which actually turns out to be something that was developed originally by a guy at Harvard, although I was in New York at the time. That was some people who use drugs do it because they are treating themselves because they have these mood problems, and they feel better when they use your stuff because it prevents feeling bad. So I got interested in that. So then I started looking at parents' mental health and childhood adversities, predicting kids using drugs. Somehow, I was getting more interested in the mental health piece than the drug piece, so I started reading that literature. And then, I went and decided I wanted to do a postdoctoral study to look at psychiatric epidemiology. So I went as a postdoc in psychiatric epidemiology, so then when I got into that environment, I discovered I was; I just thought this stuff was fascinating. So I never asked myself why — I sort of followed my notes at that point. My work was always in epidemiology and doing big surveys of drugs, mental disorders, social determinants, and more.

SN: That's a fascinating way to get into the field. So I guess for some of our late audience members, would you be willing to sort of start off with a brief description of your work in precision psychiatry and some of the main concepts?

RK: So what I'm doing now is a little different. Most psychiatric epidemiologists do observational studies essentially count heads and talk about rates of mental illness. Hence, there's a lot of arguments about how you define what a mental illness is. With a heart attack, when you see it when you know, it's kind of obvious. But what do you mean when someone is depressed? Everybody's depressed at some point, so where do you draw the line? And how does it get to a point where it's pathological as opposed to normal? So there's this enormous amount of internal argument about how to define what we're studying, which makes it harder going forward. Additionally, treatments of mental disorders are much less developed and much less well funded than for other disorders. So whereas in, say, cardiovascular epidemiology, there's a great deal of clinical epidemiology where people do giant clinical trials, there's not a great deal of that in psychiatric epidemiology — it's mostly what's called descriptive epidemiology. So, in recent years, I've gotten involved in a big study called the Army Stars study — an enormous $100 million study working with the army on the problem of suicide and the rising suicide rate among soldiers and veterans. But what we're now coming to realize this rise in suicide rates is not just among veterans, though; they're sort of the leading edge of the way. There's been a rising suicide rate for the past 15 years in quite a few segments of society in the US, whereas for the rest of the world, the suicide rate has been going down over time. So this is a very important serious problem.

We have a lot of epidemiological data suggesting that things are quite different in the US and other parts of the world. And in particular, the rates of self-reported mental disorder, anxiety, depression are much, much higher in the US than in most other developed countries. And that seems kind of curious: how could you be the richest country in the world and have all these high incidences of mental health disorders? So there's been a lot of discussion of expectations rising as wealth increases, so everybody feels poor, in comparison to the movie stars they see all the time. It is similar to ways in which everybody feels like a failure because of the achievements of others. So the key question of my new work and my interest has been to figure out what explains these rising suicide rates.

RK: It's also really important to note the uniqueness of suicide and the need to prevent it from occurring. Suicide is unique because there is no treatment for it — once it happens, a person is gone. Meanwhile, for other mental health disorders, there's not a great deal of prevention research – treatment mostly starts after the depression occurs, but don't know enough about how to stop somebody from being depressed or how to stop somebody from being anxious? In cardiology, high blood pressure can be a risk factor for certain diseases. But it's such a powerful risk factor that's now it's called an illness. So there's treatment and medication for cardiovascular problems and for pre-diabetes, that it really is prevention against other serious cardiovascular illnesses, so much so that health insurance pays for it. So health insurance will pay for you to prevent a heart attack by giving you medications to lower your blood pressure. Unfortunately, nobody's going to prevent depression by giving you a drug, but this is one of the few places where prevention is seen as important, especially in the military, who have a deep commitment to caring for soldiers and veterans.

So I found myself getting interested in clinical intervention work in psychiatric epidemiology — work that is not nearly as well developed as preventative techniques in other areas of medicine because we in psychiatry never had an opportunity to intervene in this way. Additionally, I also should mention that this work features a focus on PTSD because PTSD is the other major illness seen in this demographic of individuals. In particular, I bring up PTSD because PTSD is an illness, and it also happens to be the one major mental health illness where prevention really makes sense. The reason for this fact is because that the majority of people who develop PTSD after a traumatic event show up in an emergency room within 24 hours of having the traumatic event, and the PTSD officially develops 30 days later. So allowing prolonged, untreated periods for individuals to suffer through nightmares or other events related to traumatic incidents can lead to PTSD. In fact, if you track people after these kinds of accidents, the great majority of people have a hard time, but eventually, it can go away, but for some people, it doesn't go away. So in that 30-day window after an accident, where a patient is shaken up, there's an opportunity to intervene to prevent the onset of the disorder in a way that cardiologists do all the time.

So I've found myself by working with the military getting very interested in this intervention stuff. One of the things we've seen in this study is that tragedies like suicide are rare events, and there are some interventions that work, but you can't administer interventions on a wide scale for millions or billions of people for feasibility reasons. So, instead, you've got to figure out who are the high-risk people, and then you need to figure out when and how you can intervene to prevent suicide in these cases. This work becomes the core of the precision psychiatry with which I work, and it is a fascinating and unique discipline.

SN: That's fascinating. We invite our readers to read more of Dr. Kessler's work in the future if they have more interest in the subject. Thank you so much for the interview Dr. Kessler; it was an honor to have you.