We don’t know enough about the brain.
We’re much less successful at treating brain illnesses than those that originate in other parts of the body. About half of schizophrenics will relapse or never get their lives in order. There’s very little we can do for dementia. Huge numbers of people experience depression, anxiety, and other mental health problems without getting help.
Why? Psychiatry has not been able to match the success in other kinds of medicine because we rarely can draw direct connections from the brain to symptoms in patients or remedies, explains Joseph Herbert, emeritus professor of neuroscience at the Cambridge Centre for Brain Repair at the University of Cambridge, and the author of “Testosterone: Sex, Power, and the Will to Win.”
Neuroscience is still too young to help us really understand, or predictably change, people’s experiences. Although we know something about how neurons work, there are around 100 billion neurons in the human brain. Each one can communicate with about 10,000 others — which adds up to around 1,000 trillion possible connections.
Right now, neuroscientists can’t say that a particular neuron’s activity is matched to an experience like say, hunger, or recognizing a face. The studies you read can only tell you that during an experience, a particular part of the brain “lit up” on a brain scan. Those areas are large and include many neurons and connections.
We also don’t understand how or why their activity produces our experiences. As Herbert puts it, we know that “visual information is passed progressively through a series of visual detection areas, each extracting one element of the things we see (shape, color, and movement). Then — the mystery. Somehow the brain fuses all this together so we see one object, with all its attributes, as a single experience. We don’t understand how this happens. Though we can measure the activity of the neurons in these various areas, we can’t construct a plausible scheme whereby this activity is responsible for the phenomena that we know occur there.”
Medical knowledge of the heart, the liver, or other parts of the body hasn’t helped us understand the brain, Herbert says. Furthermore, human brains also don’t work like computers. Brains work through electricity and chemistry; computers are just electronic.
Today, if you go to a psychiatric clinic, you will not receive a blood test or be hooked up to a machine that measures brain activity. People may think we understand depression because you’ll hear that it is caused by a disorder involving the chemical serotonin. The most common antidepressants change the activity of serotonin or noradrenaline. However, a pathologist cannot look at the levels of serotonin or noradrenaline in someone’s brain and know whether he is depressed. A depressed person’s brain looks the same as someone who feels fine. A diagnosis will be based on the symptoms, what you report about your experience.
All medicine was once based on reports on symptoms; now psychiatry is the only area of medicine that has no reliable physical tests. Psychiatrists don’t know what to look for, physically, in the brain of a psychiatric patient.
The American Psychiatric Association has created lists of symptoms to help psychiatrists match them to a condition with a name — in other words, make a diagnosis. But the diagnoses are broad, including many symptoms, and people vary. You might experience some symptoms and not others. The same symptoms can occur in different illnesses as well.
In the history of medicine, we have often found treatments that worked before we understood why. The field of neuroscience is booming, and there’s great excitement in molecular and cell biology and genetics.
We can also look for advances in psychology, which studies human behavior, and clinical psychology, the science of how to help people change their behavior and experience.
There has been much progress in neuroscience, too. When we do know more about the brain mechanisms behind mental symptoms, we classify the problem as “neurological.” So Alzheimer’s, for example, is now considered a neurological, rather than a psychiatric, problem. Herbert believes that this means we’re more likely to find a cure for Alzheimer’s than for illnesses where we don’t understand the brain mechanism. One day Herbert says, “someone, somewhere will make the critical step, or steps, and we will enter a new world of psychiatry.” That day will come when we have insights that allow neuroscientists to predict a neurological or psychological experience from looking at data.
April 03, 2020
Christopher Nystuen, MD, MBA