Tuesday, July 7, 2009
"We're being told by experts to quit describing mood disorders as chemical imbalances. What metaphor or analogy shall we deploy to replace chemical imbalance?"
Moira was responding to a piece I posted from a bipolar conference a couple of weeks ago where I had this to report: "We're not talking 'imbalance of chemicals of the brain,' Dr Manji reminded his audience. Instead, think of mood disorders as 'impairments of synaptic and neural plasticity.'"
What this means is that instead of conceptualizing the brain as some sort of uniform chemical soup that could use a bit more serotonin or dopamine, we need to see the brain as a highly intricate ecosystem that requires sophisticated nurture and cultivation. In a guest blog post here, Cristina Romero had this to report from a talk by Kay Jamison:
"The brain is like a pond. It’s like an ecosystem. You want to get the ideal ecosystem and then you don’t want to disturb it very much. ... You want to really create a stable environment."
The brain, like an ecosystem, is highly complex, non-linear, and self-organizing. Both brain scientists and environmentalists describe this self-organizing principle as "homeostasis," where the system maintains its own equilibrium at a particular "set point." Robert Sapolsky in "Why Zebras Don't Get Ulcers" gives the example of perspiration to regulate body temperature.
But what if we're in the desert? If we keep perspiring, we will lose water and die. Here's where "allostasis" kicks in: We stop sweating buckets, our mucus dries up. Once the crisis is over, our body reverts to normal, or - in response to changing circumstances - it may find a new set point.
With "allostatic overload," we are talking system breakdown, such as what may happen with global warming or what is going on right now with the current economic-financial crisis. Allostatic overload is what happens to us when our brains fail to cope. Those of us with mental illness reach overload fairly quickly. When this happens, our brains simply don't reset to normal. We find ourselves caught in a destructive dynamic, trapped in our thoughts and emotions.
Ecosystems operate on "macro" and "micro" levels. This corresponds to the "impairments of synaptic and neural plasticity" that Dr Manji was talking about. Until recent advances in brain imaging and gene technology, we had a vague macro idea of neurotransmitter traffic, which gave rise to the "monoamine hypothesis" to explain mood disorders and other mental illnesses.
A gross oversimplification of this hypothesis resulted in the "chemical imbalance" myth of mental illness, best illustrated in the Zoloft ad below:
Of course, as Dr Sapolsky mentioned in an educational video, the brain is not "undifferentiated tofu." A serotonin or dopamine lube job is is not going to have the same uniform result in different areas of the brain.
Below is a far more sophisticated macro view of the brain:
In the fMRI image, we can view how one particular pathway between two different areas of the brain is supposed to operate when things are going right. When things go wrong, that narrow arrow on the right becomes wide.
The arrows represent neurotransmitter traffic, busy and focused on the left, light and broken up on the right. Too much traffic on the right means the emotional part of the brain is dominating the conversation with the rational part of the brain, which happens a lot of the time to those of us with bipolar.
Think of this macro view as the brain working (or not working) on a "systems level." The "cellular level" represents the micro view. Recall "Nerve A" and "Nerve B" from the Zoloft ad. They were largely empty. Here's an approximation of what is really going on inside the neuron:
When things go wrong inside, the neuron may shrivel and even die. On a macro level, when neurons go off-line and fail to communicate (via neurotransmitters) with other neurons, entire brain systems are compromised. We lose our ability to think and function.
As you can guess, "macro" and "micro" are interconnected. Each regulates the other in highly intricate and virtually infinite ways. When things go right, we can only marvel at this creation of nature. When things go wrong, it's not just a chemical imbalance - it's a catastrophe, a collapse. Think "ecosystem."
Much more in future blog posts ...
Check out the Science section to mcmanweb. A sample:
"By learning what happens after dopamine binds to its target neuron, we have been able to behold the brain’s inner watch works and marvel over its elegant complexity. This, in turn, is adding to our understanding of the outer watch works, namely how different parts of the brain talk to each other and how various neurotransmitter systems interact."