Sunday, January 29, 2012

A pain in the back...  

I have friends and family who suffer from back pain, and Jonah Lehrer clarifies what we know in a brilliant article about the boundaries of our understanding of cause-and-effect.
Today, back pain is an epidemic. There's an 80 per cent chance that, at some point in your life, you'll suffer from it. There are so many moving parts in the back that doctors have always had difficulty figuring out what, exactly, was causing a person's pain. As a result, patients were typically sent home with a prescription for bed rest. This treatment was very effective. Even when nothing was done to the lower back, about 90 per cent of people with back pain got better within six weeks. The body healed itself, the inflammation subsided, the nerve relaxed.
For years, this hands-off approach remained the standard medical treatment. That all changed, however, with the introduction of magnetic-resonance imaging in the late 70s. These diagnostic machines use powerful magnets to generate stunningly detailed images of the body's interior. Within a few years, the MRI machine became a crucial diagnostic tool. The view afforded by MRI led to a new causal story: back pain was the result of abnormalities in the spinal discs, those supple buffers between the vertebrae. The MRIs certainly supplied bleak evidence: back pain was strongly correlated with seriously degenerated discs, which were in turn thought to cause inflammation of the local nerves. Consequently, doctors began administering epidurals to lessen the pain, and if it persisted they would surgically remove the damaged disc tissue.
But the vivid images were misleading. It turns out that disc abnormalities are typically not the cause of chronic back pain. The presence of such abnormalities is just as likely to be correlated with the absence of back problems, as a 1994 study published in The New England Journal of Medicine showed. The researchers imaged the spinal regions of 98 people with no back pain. Two-thirds of normal patients exhibited "serious problems" such as bulging or protruding tissue. In 38 per cent of these patients, the MRI revealed multiple damaged discs. But none of these people was in pain. The study concluded that, in most cases, "the discovery of a bulge or protrusion on an MRI scan in a patient with low back pain may frequently be coincidental".
This is not the way things are supposed to work. We assume that more information will make it easier to find the cause, that seeing the soft tissue of the back will reveal the source of the pain, or at least some useful correlations. Unfortunately, that often doesn't happen. Our habits of visual conclusion-jumping take over. All those extra details end up confusing us; the more we know, the less we seem to understand. The only solution for this mental flaw is to ignore a wealth of facts, even when the facts seem relevant. This is what's happening with the treatment of back pain: doctors are now encouraged not to order MRIs when making diagnoses.
The failure of torectrapib has not ended the development of new cholesterol medications -- the potential market is simply too huge. Although the compound is a sobering reminder that our causal beliefs are defined by their oversimplifications, that even the best-understood systems are still full of surprises, scientists continue to search for the magic pill that will make cardiovascular disease disappear. Ironically, the latest hyped treatment, a drug developed by Merck called anacetrapib, inhibits the exact same protein as did torcetrapib.
The initial results of the clinical trial, made public in November 2010, look promising. Unlike its chemical cousin, this compound doesn't appear to raise systolic blood pressure or cause heart attacks. (A larger clinical trial is under way to see whether the drug saves lives.) Nobody can conclusively explain why these two closely related compounds trigger such different outcomes or why, according to a 2010 analysis, high HDL levels might actually be dangerous for some people. We know so much about the cholesterol pathway, but we never seem to know what matters.
Chronic back pain also remains a mystery. Doctors have long assumed that there's a valid correlation between pain and physical artefacts -- a herniated disc, a sheared muscle, a pinched nerve -- yet there's a growing body of evidence suggesting the role of seemingly unrelated factors. A recent study published in the journal Spine concluded that minor physical trauma had virtually no relationship with disabling pain. Instead, the researchers found that a small subset of "nonspinal factors", such as depression and smoking, were most closely associated with episodes of pain. We keep trying to fix the back, but perhaps the back isn't what needs fixing. Perhaps we're searching for causes in the wrong place.
The same confusion afflicts so many of our most advanced causal stories. Hormone-replacement therapy was supposed to reduce the risk of heart attack in postmenopausal women -- oestrogen prevents inflammation in blood vessels -- but a series of recent clinical trials found that it did the opposite, at least among older women. (Oestrogen therapy was also supposed to ward off Alzheimer's, but that doesn't seem to work, either.) We were told that vitamin D supplements prevented bone loss in people with multiple sclerosis and that vitamin E supplements reduced cardiovascular disease. Neither turns out to be true.
Given the increasing difficulty of identifying and treating the causes of illness, it's not surprising that some companies have responded by abandoning research. Most recently, two giant firms, AstraZeneca and GlaxoSmithKline, announced that they were scaling back research into the brain. The organ is too complicated, too full of networks we don't comprehend. We live in a world in which everything is knotted together, an impregnable tangle of causes and effects. Even when a system is dissected into its basic parts, those parts are still influenced by a whirligig of forces we can't understand or haven't considered or don't think matter.
This doesn't mean that nothing can be known or that every causal story is problematic. Some explanations work better than others, which is why, thanks largely to improvements in public health, the average lifespan in the developed world continues to increase. Although our reliance on statistical correlations has strict constraints -- which limit modern research -- those correlations have managed to identify many essential risk factors, such as smoking and poor diet.
And yet, we must never forget that our causal beliefs are defined by their limitations. For too long, we've pretended that the old problem of causality can be cured by our shiny new knowledge. If only we devote more resources to research or dissect the system at a more fundamental level or search for ever more subtle correlations, we can discover how it all works. But a cause is not a fact, and it never will be; the things we can see will always be bracketed by what we cannot. And this is why, even when we know everything about everything, we'll still be telling stories about why it happened. It's mystery all the way down. [More][Apologies for a very liberal excerpt, but the whole piece is worth the time, albeint mildly discouraging]
I have been puzzling for some time about the anti-scientific mood in much of America, or at least a "cafeteria" approach to science and technology. We choose when adherence to the scientific method is applicable. For farmers, it displays as staunch defense GMO's with arguments they deny for climate change. This list includes vaccinations, environmental cancer causes, flood control, meat consumption, and other hot-button issues.

I've written about our profession's approach to science before. In agriculture, we justify it by carefully annotating some science as "sound". Curously, sound science is always research that validates our position.

Sound science doesn’t just line up on one side of an argument either. Anyone who has been to a congressional hearing or in major litigation can witness a parade of sound scientists contradict one another – for a hefty fee, of course.
When EU customers won’t buy GMO corn for obviously trumped up health issues, I really doubt that a mountain of sound science will suddenly change their minds. It certainly hasn’t for US producers. Sound science has quietly pointed out that market advisors are virtually ineffective – although better than farmers themselves – compared to random choice, but producers still fork out hefty fees and mumble mantras of technical mumbo-jumbo. Sound science points out that wind energy is a non-starter because of the backup generators required, but it looks like such a great idea and if we can get a subsidy the science won’t really matter.
Sound science would also demand that no tractor be operated without a closed cab (interestingly, something our “non-science” EU cousins believe and we don’t) or by operators over 65. 
What might be happening is the clash between how much cultural change we can absorb and the pace of scientific progress. But watching the anger of the Tea Party and the mystical surreality of modern spirituality on the other side, it appears neither wing has much respect for plodding efforts by scientists to push back the boundaries of ignorance.

Meanwhile, we want our phones to work and our cars to drive themselves and life to become easier, faster and cheaper every day. My observation is electronic advancement is far more likely to be embraced than medical or geophysical. One is too close to home, the other has too many long time horizons. In those areas we reserve the right to manufacture our own belief systems, even though I think it is those seemingly disassociated technologies that are wrenching our intuitive understanding of the world the most.

My concern is that making the scientific method a handmaiden to our particular agenda renders it worthless. Our minds will have to work overtime to rationalize mysticism here and physics next door. Most of all, it appears the failings of our education system in STEM courses makes the option of "going with the gut" or "feelings" a  choice that cannot be criticized even with it's dismal results.

Religion is caught in the divergence from seeing the world dispassionately and empirically. Hence the rise of atheism or at least a "none-of-the-above" spirituality that is becoming the refuge for those seeking meaning and forced to choose between reason and faith.

We've struggled with this rift before, of course, but we now have so much power (ironically thanks to science) to change our world and lives, that the philosophical nature of the debate is dwarfed by the scale of possible consequences. 


Karl M. Hess said...

John, Who was the guy who said that a 10 lb weight would fall faster than a 1 pound weight? That was gospel for centuries until Galleo (?) somebody, actually went to the top of the leaning tower of Piza and dropped the 2 simultaneously and to the astonishment of the observers, they hit at the same time, (do tell; mass and acceleration at 14.7 ft/sec) but no one changed their minds about the previous theory however. My father was fond of saying, that it is hard to have a discussion with someone who is approaching the discussion saying 'my mind is made up, do not confuse me with the facts'.

Karl Hess said...

answering my own question. The original proponent of heavier objects fall faster was Aristotle.

Anonymous said...

The eyes can see only what the mind is prepared to comprehend

Anonymous said...

At what point are we prepared to accept that our bodies, climate, planet, and universe are more complicated than we understand? Maybe we will never understand all of the complexities. I'm not suggesting that we halt all research. However, is our quest for knowledge distracting us from more pressing matters? Are we using our resources appropriately? I see I've created more questions than answers...