If you close your eyes and think about it for a while, as philosophers have done for centuries, the world of the mind seems very different from the one inhabited by our bodies. The psychic space inside our heads is infinite and ethereal; it seems obvious that it must be made of different stuff than all the other organs. Cut into the body, and blood pours forth. But slice into the brain, and thoughts and emotions don't spill out onto the operating table. Love and anger can't be collected in a test tube to be weighed and measured.
Rene Descartes, the great 17th century French mathematician and philosopher, enshrined this metaphysical divide in what came to be known in Western philosophy as mind-body dualism. Many Eastern mystical traditions, contemplating the same inner space, have come to the opposite conclusion. They teach that the mind and body belong to an indivisible continuum.
In the past, doctors and scientists have tended to dismiss that view as bunk, but the more they learn about the inner workings of the mind, the more they realize that in this regard at least, the mystics are right and Descartes was dead wrong.
Mind and body, psychologists and neurologists now agree, aren't that different. The brain is just another organ, albeit more intricate than the rest. The thoughts and emotions that seem to color our reality are the result of complex electrochemical interactions within and between nerve cells. The disembodied voices of schizophrenia and the feelings of worthlessness and self-hatred that accompany depression, although they seem to be based on reality, are no more than distortions in brain electrochemistry. Researchers are learning how these distortions arise, how to lessen their severity and, in some cases, how to correct them.
Scientists are also learning something else. Not only is the mind like the rest of the body, but the well-being of one is intimately intertwined with that of the other. This makes sense because they share the same systems--nervous, circulatory, endocrine and immune. What happens in the pancreas or liver can directly affect brain function. Disorders of the brain, conversely, can send out biochemical shock waves that disturb the rest of the body. The pages that follow, our annual special report on health, take you to the cutting edge of mind-body research, where scientists, having left Descartes's great mistake far behind, are exploring how the brain works, how it malfunctions, and what can be done when it goes awry.
--By Michael D. Lemonick