By Sonya Collins
WebMD Health News
What are we learning about our brain and mental health? Amit Etkin, MD, PhD, assistant professor of psychiatry and behavioral sciences at Stanford University, spoke on that topic as part of an expert panel at the Association of Health Care Journalists annual conference last week. WebMD spoke to Etkin about how technology is helping us learn more about the causes and treatment of depression and other mental illness.
Q: What can brain imaging tell us about depression, anxiety, and PTSD?
A: Imaging can tell us how similar a person with any one diagnosis is to another and how similar or different people are who have the same diagnosis. It can also help us predict who will respond to what kind of treatment.
There are cases where you see similarities in brains across two similar disorders, or you can see differences between similar disorders. But the really surprising thing is actually the similarities across disorders that aren’t symptomatically that similar. The checklist of symptoms that we use to make diagnoses suggests that diagnoses like drug abuse or schizophrenia or depression are actually separate disorders, but imaging shows that they still share some common biology. That speaks to the limited nature of our diagnostic checklists to begin with and how much the brain can tell us.
Mental illnesses have always been defined by their symptoms. But symptoms are just external cues that something is going on. If a person doesn’t report symptoms or no longer has the behavior, it doesn’t seem logical to conclude that there’s not something still going on in their brain. For example, with drug addiction, you can stop using drugs, but there’s a major risk of relapse, and that has to do with something continuing in the brain even after you stop using. Ultimately imaging is our only measure of the brain itself. Psychiatry has to be grounded in the biology of the brain as the organ that underlies mental illnesses. As such, having a tool that tells us something about the brain, however precise, is already an important step forward.
Q: What is transcranial magnetic stimulation (TMS), and how might it help people with depression?
A: TMS is a non-invasive way of stimulating the brain. It uses a powerful electromagnet that you place outside of the head, targeted at one specific part of the brain. It turns on a magnetic field that’s as strong as a regular MRI but lasts less than half of a millisecond. This magnetic field turns on or off neurons in the brain, such as those that contribute to depression. If you then do this repeatedly over time, you end up retraining the particular circuits that you’re targeting to function correctly on their own.
The FDA approved it to treat depression, and it’s being studied in a range of other conditions. It’s the first treatment approach that takes particular circuits in the brain as a primary target and affects them directly to treat depression.
Q: Can we expect to see TMS emerging to address other psychiatric issues?
A: People are using TMS in any number of conditions, whether it’s chronic pain, schizophrenia, OCD (obsessive-compulsive disorder), PTSD, or others. For the most part, those TMS interventions are essentially very similar to the one for depression. Research is exploring which circuits in the brain we should target with TMS. Ultimately, we cannot target the same one area that we have targeted with TMS for depression over the last 20 years, but have to find the ones that are right for the individual person and their illness.
Q: How can computer-based training help people with PTSD and depression, and what exactly does the training entail?
A: Computer training tries to link an understanding of what’s wrong with the brain with a task that directly exercises that area of the brain. You give someone that task, repetitively, and make it harder and harder as they go along so that they get better and better at that task. The idea is that the brain circuit associated with the mental illness will then function better in other contexts of daily life.
It’s cutesy and fun versions of the same cognitive tasks that neuroscientists have been giving people forever. But it might look more like a video game so it’s entertaining. It has you wanting to do more rather than feeling like you’re in a laboratory experiment. Maybe you’ll see birds flying by, or see something jumping on the horizon, and you need to click on it.
It feels like a video game, but under the hood it’s manipulating and enhancing particular cognitive functions by making you work faster, more accurately, resist distractions, and so forth.
It has been shown to work best for schizophrenia, and is moving towards FDA approval in the next couple of years. Schizophrenics have a very profound cognitive impairment in something called executive function. That’s your ability to think flexibly, shut out distraction, switch between tasks, retain information in your mind and manipulate it.
If you train people with schizophrenia to do those executive functions over and over … and make it harder and harder, they actually get better at those functions and better in terms of dealing with life in general. They’re not cured, but it’s something that current medications, antipsychotic medications for example, cannot do. It’s been firmly established that antipsychotic medications don’t touch cognition.
Q: To what degree do we need novel treatments for depression, anxiety, PTSD? How are the current treatments lacking or flawed?
A: Every current medication was discovered by chance. Other treatments, like psychotherapy, are based on general psychological principles that don’t directly get at what’s wrong with the brain. So we aren’t getting people better to the degree that we need to. Even with the best interventions that we have for any illness, only about half of the people get better in a lasting way.
There are a lot of people that end up managing their mental illness as a chronic disease. My interest and the interest in the field is in developing novel treatments that come from an understanding of the biology of the brain, that really are targeted directly at the problem at hand.
There’s an idea about antidepressants causing the birth of new neurons in the brain, and that those new neurons might better address the depression than the chemical effects of the antidepressant do. If that’s the case, why are we starting out so far away from the ultimate target? Why do we bathe the brain in a medication instead of directly targeting those circuits?
Oral antidepressants do change things that probably relate to why you have depression, but not directly. One of the reasons it takes so long for an antidepressant to work is that it’s changing A that changes B that changes C that changes D, and maybe D is the thing that really needs to be changed. So it’s very indirect.
In the same way, we already know a lot about the brain circuitry we want to be able to target for a range of mental illnesses, but have lacked the tools, especially non-invasive ones. Current TMS methods, for example, are powerful but can still only reach a small portion of the brain. We are currently developing new non-invasive tools that could reach any part of the brain in order to go at the problems in mental illness directly. To do this, psychiatrists must work closely with neuroscientists, engineers, psychologists and many others, which itself takes a new scientific culture to achieve. Ultimately, our goal is to find new ways of getting people better and better faster, which has to involve a break with the status quo.