Molecules of Emotion

"Molecules of Emotion" by Candace Pert. Scribner, 1997.

This book is more unusual than it appears at first sight. To get a quick impression of what kind of book I'm holding in my hands, I find the last pages often more revealing than the first. In this case, I was mystified. In Appendix B I found twenty pages of addresses of outfits devoted to such pursuits as biofeedback, body psychotherapy, guided imagery and visualization, hypnotherapy, acupuncture, ayurveda, naturopathy, macrobiotics, feldenkrais, hellerwork, myotherapy, polarity therapy, reflexology, reiki, rolfing, craniosacral therapy, therapeutic touch, meditation, yoga, and more.

After the Appendixes I found an alphabetically arranged Glossary of biochemistry terms beginning with agonist/antagonist, amino acids, analog, antibody and ending with steroids, synapse, T4 receptor (CD4), and VIP (Vasoactive Intestinal Peptide). This contrast suggested that the book would be one of those fashionable books that abuse scientific terms to lend an aura of respectability to a load of fluff. Yet, in spite of this inauspicious first impression, I continued to where the author intended me to start. That way I learned that Dr Pert is a biomedical researcher, a major player in what she calls the "receptor revolution".

What are receptors? Since the 1920's insulin had been used as a treatment for diabetes. Insulin was known to be a compound in the chemical sense (it is a small protein) and its composition was known. Somehow it has an effect on the cells in the human body, but the mechanism of the effect was a mystery.

Even more intriguing were opioids, substances that produce morphine-like effects. Opioids are used medically to relieve pain. They also produce experiences variously described as euphoria or bliss. Again an example of a compound of known composition mysteriously affecting cell behaviour.

For decades pharmacologists had posited that body cells had "receptors". A bit of a cop-out, as if giving the mystery a name would solve it. Hard-headed scientists would have none of it.

Some of these hard-headed scientists managed to identify the opiate (the opioid in opium) receptor as a molecule, in this case a large and complex one. In this breakthrough Pert played a crucial role. The opiate receptor molecule is attached to the exterior of a cell. The shape of the molecule is such that the relatively small opiate molecule can attach to it. Presumably this changes the shape of the receptor, which causes changes in the cell's metabolism.

Mammals did not evolve while habitually using opium. The body must be producing a similar substance with the same effect. As soon as the opiate receptor was identified the hunt was on for this substance, the body's own natural painkiller. That way the first endorphins were found.

The production and consumption of endorphins, as originally discovered, took place in the brain. Later it was found that immune cells also produce endorphins (page 161). In the meantime it was found that neurotransmitters also act via receptors and that they also occur outside the nervous system.

This is what Pert refers to as the "receptor revolution": not only diabetes and hypothyroidism are understood chemically, but maybe also mental disorders. It opens the door to molecular medicine. Take for example depression (page 267). Depression is associated with low serotonin, one of the neurotransmitters. It is easy to jump to the conclusion that depression is caused by low serotonin. So if you can find a compound that decreases serotonin re-uptake you have a cure for depression. But the mammal body is not that simple. For example, serotonin not only plays a role in the brain, but the gut is rich in serotonin receptors. Prozac causes the gut to be flooded with excess serotonin; patients on this drug often have gastrointestinal disorders.

A large part of the book is taken up by an account of discoveries of many new "information substances", the terms used to describe the dozens of transmitters, peptides, and hormones. Moreover, receptors for these are found in many organs throughout the body. The result is that mind and body function as a complex network of interlocking feedback circuits. In electronics we don't build such wildly complex systems, as their behaviour is unpredictable and they are uncontrollable. For one thing "cause" and "effect", that bedrock of rationality, are no longer useful terms. It should not be a surprise that a simplistic intervention like the administration of Prozac has unpredictable consequences.

The premiss of molecular medicine is that the control system that is the body/mind is understood well enough to engineer precisely controlled interventions. Halfway through the book we reach the stage where Pert sees the falsity of the premiss of molecular medicine. She sees the approaches listed in Appendix B as having more promise than molecular medicine. This seems to me in contradiction with the subtitle of the book: "The science behind mind-body medicine". As far as I can tell, science has not even started to bridge the gap between all the exciting new chemistry and a mind-body medicine where healing is the rule and harm the exception.