Sally Satel is a psychiatrist and resident scholar at the American Enterprise Institute. She is co-author of “Brainwashed: The Seductive Appeal of Mindless Neuroscience.”

In “Cure,” Jo Marchant, a British biologist turned science writer, sets out to show that states of consciousness such as hope, fear, stress and loneliness affect health. She believes that doctors and scientists of the medical establishment “ignore or downplay” this reality and hopes her book will “convince the skeptics [of mind-body phenomena] to reconsider what they might be missing.”

“Cure” begins with perhaps the best studied of mind-body interactions: the placebo effect. That is, the expectation — one’s hope — that a therapeutically intended intervention, even one devoid of any biologically active substance, will work.

An impressive example of this endlessly fascinating effect is the response of some Parkinson’s patients to an inert pill. Not only do they experience reduction in hand tremors and muscle rigidity — the same response enjoyed by patients who take their actual dopamine-enhancing medication — their brains also manifest an increase in dopamine activity. Remarkably, it appears that the mere expectation of relief alters their neurochemistry, as demonstrated by brain scans.

A placebo can exert its effects even when the patient knows it’s just a sugar pill — as opposed to knowing that the pill might be the real thing (as is the case in clinical trials). It’s essential, though, that patients be aware they are receiving a placebo if they are to benefit; if it is slipped into food or disguised in some way, it won’t have any effect. (Tellingly, animals are not known to have responses to placebos — they can’t “hope” a pill will help them feel better.)

‘Cure: A Journey into the Science of Mind Over Body’ by Jo Marchant (Crown)

Conditioning is another mental phenomenon with a potential effect on symptoms. The mechanism is based on the Pavlovian paradigm wherein a conditioned stimulus (a bell) paired with an unconditioned stimulus (food) comes to produce a similar response (salivation) on its own, absent the food. Consider: Some children with attention deficit hyperactivity disorder who take their normal ADHD medication paired with a green-and-white placebo capsule eventually need only half the active medication along with the fake capsule to control their symptoms.

In short, reliably coupling the fake capsule with the real pill signals to the brain that a normal dose is being ingested. Notably, the children are well aware that the green-and-white capsule is inert. This effect works in animals as well. Researchers at the University of Florida, for example, conditioned rats to expect morphine or saltwater by giving injections of one or the other for two sessions. Researchers then gave both groups the saline injection during a third session. In response, about 30 to 40 percent of the group that had previously received morphine acted as if they had received morphine again and showed pain relief.

The chapter on conditioning stood out as fresh and intriguing. The remaining chapters, however, about the promise of neuroplasticity and the perils of chronic stress, have been well-covered in other books: recently in “The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human” by V.S. Ramachandran and “Loneliness: Human Nature and the Need for Social Connection” by John T. Cacioppo and William Patrick. The myriad studies cited in “Cure,” some preliminary and uncontrolled and others well-replicated, underscore how “intangible, immaterial treatments can have real physical benefits.” But, as Marchant notes, placebo effects are largely limited to patients’ subjective symptoms, especially depression and pain. One effect is not equal for all conditions; nor do all patients with a certain condition respond equally.

When it comes to cancer, for example, mind-based therapies do not prolong life. Although stress reduction can lead to patients taking better care of themselves and more faithfully sticking to prescribed treatment regimens, the malignancy itself is unaffected. Patients with asthma report breathing more easily after a placebo, but objective tests of lung function reveal no improvement. In both cases, the underlying pathology remains. Despite the title of the book, few, if any, are cured.

To be sure, experiencing less misery is a huge benefit for patients and their families. Practices that can bring about such relief should be taken very seriously indeed.

The book is written as a series of dispatches. The author travels to the Italian Alps, Germany and Harvard to visit patients, research subjects and researchers who are “swimming against mainstream opinion to study the effects of the mind on the body, and using that knowledge to help patients.” She includes herself, too, comparing the technical, anonymous, hospital-based delivery of her first child with the warmth, reassurance and continued midwife support of her second birth, at home.

Marchant, a former editor for Nature and New Scientist, is properly dismissive of the idea that junk medicine such as homeopathy and energy fields heal in the ways their proponents claim. One particularly instructive scenario concerns the transformation of a man who used a wheelchair. In the 1960s, he was diagnosed with a lethal osteosarcoma in his pelvis and visited Lourdes hoping to be cured. He could soon walk and lived to old age, becoming one of the 63 official miracles of Lourdes. Cleverly, Marchant, who volunteered at the baths at Lourdes, took the man’s medical records to an expert at the Royal National Orthopedic Hospital who examined old tissue samples and concluded that the patient did not have an osteosarcoma, but rather a lymphoma that had been sensitive to a chemotherapeutic agent that the patient had taken long ago.

“Cure” is for anyone interested in a readable overview of recent findings in mind-body phenomena, a reliably enthralling topic. It is heavy on reporting and presents interesting facts, but is light on original analysis and historical and cultural context.

The quirky thing about “Cure” is the author’s lamentation that mainstream medicine dismisses the mind’s influence on health. That might have been so 50 years ago, but it’s far from true today. For example, 14 of the 15 top U.S. medical centers, as ranked by U.S. News & World Report, all have centers for integrative medicine (the new name for alternative and complementary medicine). To the extent that skeptics exist, however, she will probably succeed in opening their eyes.

Another problem is that Marchant is a bit rusty on psychiatry. She writes, “The conventional medical view is that depression results from a chemical imbalance in the brain — a lack of the neurotransmitter serotonin.” Scientists now think about depression in terms of defects in brain circuitry while taking account of the effects of environmental factors on gene expression during critical intervals of development. Another puzzler: “Psychological therapies are an increasingly popular alternative” [to antidepressants]. Not so. Targeted psychotherapies were in use in the 1960s for depression and the 1950s for phobias.

For those seeking an introduction to mind-body interaction, “Cure” is a rewarding read that seeks to separate the wishful and emotion-driven from the scientifically tested. But just as many practitioners of alternative medicine oversell what their ministrations can do, too much of the book presents itself as breaking news when the power of mentality over matter, while far from completely understood, is not an exotic truth.

A Journey Into the Science of Mind Over Body

By Jo Marchant

Crown. 300 pp. $26