Feeling moody lately? It could be a lack of sleep, or a stressful new job – or it could be your bones. A new study published in the journal Cell by the French geneticist and physician Gerard Karsenty explores osteocalcin, a protein that sends signals from the bones to the rest of your body to regulate processes in the body. Karsenty, now a professor at Columbia University in New York, has been working on these experiments since the mid-90s. Amanda Schaffer wrote about him for the New Yorker recently:
Karsenty showed that bone plays a direct role in memory and mood. Mice whose skeletons did not produce osteocalcin as a result of genetic manipulation were anxious, depressed, and almost completely unable to master a test of spatial memory. When Karsenty infused them with the missing hormone, however, their moods improved and their performance on the memory test became nearly normal. He also found that, in pregnant mice, osteocalcin from the mother’s bones crossed the placenta and helped shape the development of the fetus’s brain. In other words, bones talk to neurons even before birth.
Our bones decay, like the rest of our bodies, and with bones go osteocalcin. When Karsenty deprived mice of osteocalcin, he found that they became lethargic, saying that “they never rebelled or tried to bite or escape.” Right now, there’s nothing conclusive or even close to it, but in human terms, Karsenty believes in a theory of reciprocity concerning the different parts of the body. “If X talks to Y, then Y should talk back to X… [so] insulin acts on bone, and bone should help regulate insulin,” writes Schaffer.
If any or all of this turns out to be true, it’s groundbreaking. It changes a lot of what we know about how the human body works. Karsenty believes the skeleton is integral to “energy usage, reproduction, and memory.” The first thing I thought of reading this was how this could revolutionize Alzheimer’s treatment. More than 5 million Americans are afflicted with Alzheimer’s Disease, according to the Alzheimer’s Association. If Karsenty’s right, this could help millions of people.
This is just the first study of what’s sure to be many from Karsenty (and other scientists) on the subject, but the evidence points in Karsenty’s favor. He points out that most doctors recommend more and more exercise as we age, and exercise builds up bone strength, which means more osteocalcin in our bodies. That can only be a good thing.