Monday, August 24, 2015

Beta Amyloid Blues

I've heard of other people describe this kind of experience. A memory that has persisted and serves to mark when the internal dialog began. I was three years old, and I remember going out the back door of the church I grew up in, standing on the concrete pad and looking at the huge oak tree and thinking to myself, 'I'm three." It was just something that resonated with me, the fact that I was a person who recognized that I recognized my own existence. I'm sure thats not what I thought, explicitly, at the time, but it is the essence of the experience. I would venture to guess that just about all of us, all of humanity has experiences like this, whether or not they persist as memory landmarks, is hard to say.

Memory and the ability (or, inability) to memorize is such an intriguing aspect of life. Just about every other day I take the dog for walks at the nearby park, and have, on and off for the past few years and usually, we park at one particular lot and go for a hike. The last few times I parked down the big hill, which means passing the other lot on our hike as we head back down the hill. Every time she has tried to get me to go to the other lot. She doesn't remember that the car is down the hill. I take it for granted that I'll remember where I parked, but even this isn't guaranteed.

Alzheimers Disease (AD) has among its signs and symptoms, a specific manner in which patients have a consistent pattern of regression and experience and reliving of old memories. Recently I was reading about a study that examined just what kind of memories persist as the disease process progresses. A man in his eighties who was a Toronto taxi driver for over fifty of his years was diagnosed with AD, and until his death many years later, when he was no longer oriented to person, place or time and could not independently execute any of the standard activities of daily living he could still demonstrate that he knew his way around Toronto. Streets, directions, addresses -- it was still there and accessible. Many other examples, while not as dramatic, exist. And what they have in common is simply a matter of redundancy. A working memory, such as driving around Toronto, that is used on a daily basis for a majority of a person's life is so deeply ingrained and has, at a structural level, so many neurons devoted to this memory construct that it simply lasts the longest. Secondarily, memories that are impactful also last long. Childhood experiences are often relived by AD patients, and while the article I was reading didn't specifically address the difference, on an anatomical level in the brain between the two types of memories, but I couldn't help but wonder. Curious that, seven or eight decades after an impactful experience in childhood, even if it has not been something thought of frequently in adulthood, it still persists. The neural network that maps Toronto persists due to brute strength derived from numbers alone. If I (in a far of distant future, but one that hopefully doesn't exist, as there will be major advances in AD prevention and treatment by then) ever have to suffer through AD myself, I could imagine that my memory of stepping out into the early afternoon sunshine in Portland, looking up at a mighty oak tree and having that all too human experience of self realization, would be one that I relive even when I can not function independently at a foundational level.

I may go years without thinking back to that morning. Inevitably something will spark the memory and I'll hold on to it and savor it for a moment, giving it a nod of respect and thankfulness that its still there. Then I put it away. If I had to put a number on how many times I have done this, I would say anywhere between twenty five and thirty five times. Obviously, its persistence is not a function of redundancy. What allows it to be accessed all these years later? The details have faded over time. Of course I can fill them in, as I know the yard very well and spent years playing and running around in it. The garage, the shed,  the grapes that grew over the fence from the neighbors yard that were perfect for throwing but horrible for eating -- all this I can picture well. Those things that live in my mind are there from repetition, and I can pick out a couple of individual experiences that come to mind, but nothing like that early one when I was three years old. That memory, I contend, must derive its sturdiness from organization and configuration, not sheer power of abundance.

Geometry of structure, and the applicable physics of the tangible universe rule the macro and micro worlds (of course, exploration into worlds of scale that seem to ignore Newtonian physics and have allowed for fantastic advances in science and technology but humans proprioceptive interactions with the world are solidly physical and ruled by how the apple drops). In some ways I see my first memory that I consciously recognize as my most efficient memory. It is simple. I have no idea what happened that morning, what kind of songs were sung, or who I was playing with, or where we went for lunch, or anything like that. None of that matters because of what the memory represents, which is the beginning of me as I have always known me to be. It functions as a key to what it means to be me, and unlike most other keys in my life, I've never lost this one.

Medical school, especially the first two years is really "memory school" as there is no time to understand all of the processes, or etiologies of nomenclature. Seeing things in person and experiencing pathologies in person as if they leapt right off the page, allows the formation of 'keys' to distinct pathologies. Having a patient with Addisons Disease, which while not super complicated, is an endocrinological process with many secondary, tertiary and quaternary actions that must be recognized and managed. Learning about all these things from reading, discussion, practice questions and board review material is necessary, and with enough work and effort put in lays the foundation for truly understanding the pathology, diagnosis, management and treatment which can only be had by having a real, living human being who needs your help.

The difference between reading about something because you will be tested on it versus having a patient on the fourth floor in danger is substantial. Of course, the idea is that all those tests are preparing us to help the patient, and they do, as much as they can. Taking that knowledge and forming it into a permanent "vault" makes me think of what it must be like to give life to an inanimate objet. I build a boy out of wood, call it Addisons Disease, paint it, and lovingly put the finishing touches on what is just a static structure. Spoiler alert: the wooden boy comes to life. By trying to see the disease through the patient's eyes, the wooden boy becomes animated. Each time I see this process in a patient the boy grows and takes on a life of his own, and becomes a construct in my own mind which will teach me about this disease.

So that is kind of a weird metaphor. I'll allow it, though.

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