Sunday, April 5, 2015

Psychiatry as a Clinical Neuroscience, Why Not?

I first heard the term "clinical neuroscience" used in relation to psychiatry as a resident in 2009, when my associate program director handed out a paper to us trainees titled: "The Future of Psychiatry as Clinical Neuroscience." She presented this as a ground-breaking document that would greatly influence the rest of our careers. Shockingly, the authors of that paper did not cite NIMH Director Thomas Insel, who had an earlier article in 2005 titled: "Psychiatry as a Clinical Neuroscience Discipline." Since then, Dr. Insel has posted an updated version of the article on his blog (publication date: unknown) and wrote other blog posts championing the notion that in order for psychiatry to advance, we must focus on basic neuroscience research. And now, a recent article asks, "The Future of Psychiatry as Clinical Neuroscience: Why Not Now?"

The authors, who are program (or associate program) directors of residency training at Yale, Pitt, and Columbia, bemoan the fact that advances in understanding mental illness based on neuroscience research have not made their way into clinical practice. As barriers, they cite "the pervasive belief that neuroscience is not relevant to patient care," as well as the complexity of the research. They argue that the best place to start enacting this paradigm shift is in psychiatry residency programs right now. They also write:
The diseases that we treat are diseases of the brain. The question that we need to address is not whether we integrate neuroscience alongside our other rich traditions but how we work as a field to overcome the barriers that currently limit us. Ultimately, the most powerful force will be the improved translation of research into more refined explanatory models of psychiatric pathology and into novel therapeutics. To ensure that our field is ready to embrace new findings as they emerge, we need to begin the process of culture change today by enhancing communication and collaboration between researchers and practitioners.
I think 1BOM hit the nail on the head when he wrote: "Rather than being 'ready to embrace new findings as they emerge', tomorrow’s psychiatrist needs to know how to critically evaluate new findings as they emerge [italics in original]." I remember being taught as a resident about Broadmann Area 25 being critical in the pathogenesis of depression, based on exciting initial deep brain stimulation results from Dr. Helen Mayberg. This was almost treated as an established fact, despite the very preliminary nature of the research. Well, what happened when they tried to do a larger clinical trial? Neurocritic reported that the trial was halted before its planned endpoint in December 2013, and last month it was revealed that the medical device company conducting the trial (St. Jude) stopped it due to perceived study futility.

Do the clinical neuroscience curriculums for psychiatry residents teach the importance of humility and emphasize just how much we don't know? One of my favorite articles in the past year has been Tom Stafford's BBC Neurohacks column from December 2014 in which he discussed the importance of redundancy in the brain. He described the case of a woman who, despite missing her entire cerebellum, was able to live a fairly normal life:
This case points to a sad fact about brain science. We don't often shout about it, but there are large gaps in even our basic understanding of the brain. We can't agree on the function of even some of the most important brain regions, such as the cerebellum. Rare cases such as this show up that ignorance. Every so often someone walks into a hospital and their brain scan reveals the startling differences we can have inside our heads. Startling differences which may have only small observable effects on our behaviour.

Part of the problem may be our way of thinking. It is natural to see the brain as a piece of naturally selected technology, and in human technology there is often a one-to-one mapping between structure and function. If I have a toaster, the heat is provided by the heating element, the time is controlled by the timer and the popping up is driven by a spring. The case of the missing cerebellum reveals there is no such simple scheme for the brain. Although we love to talk about the brain region for vision, for hunger or for love, there are no such brain regions, because the brain isn't technology where any function is governed by just one part.
 As Neuroskeptic recently tweeted:
This is a point that needs to be made and repeatedly emphasized to those who write things like "the diseases we treat are diseases of the brain." The irony for me is that I do appreciate the importance of neuroscience in psychiatry and agree with the authors when they wrote: "The more sophisticated and nuanced our science becomes, the more critical it is to have individuals who can translate this work to make it accessible to students at all levels." It reminded me of one of my favorite college classes, Principles of Neuroscience. The professor, who studied ion channels in different animals, was an amazingly good teacher, and the first lecture started something like this:
"Ernest Hemmingway once boasted that he had a six-word story—complete with beginning, middle, and end—that would bring tears to anyone who heard it. Here it is [he lowered the lights in the room and said the following words softly and slowly]: 'For sale…baby shoes…never used.' [dramatic pause] While not all of you are tearing up, very few people could have heard those words without thinking of or feeling something. Any images in your mind (did you see the shoes, what color were they?), any thoughts or emotions you may have experienced after hearing those six words, formed as signals in your nervous system. Without the nervous system, we cannot see, hear, feel, taste, or smell—in short, our five senses would produce no corresponding thoughts, and life as we experience it does not exist."
The tour de force lecture progressed to descriptions of single neurons and how our nervous system is comprised of approximately 100 billion of them, each of which can have tens of thousands of synaptic connections to other neurons. The quote I remember most clearly: "All of the neurons together in one brain form more connections with each other than there are stars and planets in the galaxy." The professor ended his lecture by giving us some practical tips based on his knowledge of neuroscience. Time and repetition, he told us, is what will help us succeed in the class, because that is how neuronal circuits are programmed and how processes in the brain ranging from retrieving facts from memory to riding a bicycle become automatic. I use the same advice almost daily with my patients when I emphasize to them the importance of practicing new behaviors or ways of dealing with difficult thoughts and emotions. Similarly, based on my reading of research on the effects of sleep, exercise, and social interactions on the brain, I share with my patients the importance of getting enough of each.

I learned more neuroscience of clinical relevance in one semester from this PhD Biology professor than I have from years of attending lectures and reading papers from psychiatry researchers who are considered world experts in areas like the neurobiology of OCD, pediatric bipolar disorder neuroimaging, or how transcranial magnetic stimulation affects neural circuits in depression. For me, the most important distinction when we talk about clinical neuroscience is whether we take a broad view of neuroscience or a narrow view. The broad view would emphasize the huge effect of all of the different inputs on the brain (e.g. that six words can bring a person to tears), whereas the narrow view tends to emphasize things like genetics, neurotransmitters, biomarkers, and circuits.