A lengthy New York Times article reviews the different theories that have been offered about what happened to some U.S. diplomats in Cuba starting in December 2016. The article then concludes by saying that to this date no one really knows the cause(s).
The article, however, presses the question of whether the diplomats symptoms “are primarily psychogenic — or ‘functional’ — in nature. If true, it would mean that the symptoms were caused not by a secret high-tech weapon but by the same confluence of psychological and neurological processes — entirely subconscious yet remarkably powerful — underlying hypnosis and the placebo effect. They are disorders, in other words, not of the brain’s hardware but of its software; not of objective injuries to the brain’s structure but of chronic alterations to how the brain functions, typically following exposure to an illness, a physical injury or stress. . . . [Such disorders are] the most misunderstood, debilitating and denigrated ailments known to medicine.”
Nevertheless, the State Department and the diplomats themselves have rejected this theory.
According to the article, one of the leading experts on such disorders is Dr.Mark Hallett, “who is the Chief of the Medical Neurology Branch and the Human Motor Control Section of the National Institute of Neurological Disorders and Stroke (NINDS), which is part of the National Institutes of Health. He obtained his A.B. and M.D. at Harvard University, had his internship in Medicine at the Peter Bent Brigham Hospital and his Neurology training at Massachusetts General Hospital plus fellowships in neurophysiology at the NIH and in the Department of Neurology, Institute of Psychiatry in London.”
Last year the National Institutes of Health asked Dr. Hallett to examine the diplomats, but the State Department did not appoint him to the task force for such examinations, and that Department and NINDS have instructed De. Hallett not to speak with the author of the Times article.
 Hurley, Was It an Invisible Attack on U.S. diplomats, or Something Stranger?, N.Y. Times (May 15, 2019). This blog has many posts about the issues posed by the medical problems of some U.S. diplomats in Cuba (and more recently in China). See the “U.S. Diplomats’ Medical Problems in Cuba, 2016–??” section of List of Posts to dwkcommentaries—Topical: CUBA.