Mark Hallett

Mark Hallett, an acclaimed neuroscientist who transformed movement disorder treatment and mentored hundreds of researchers around the globe, died at home on Nov. 2, age 82. The cause of death was glioblastoma, a form of brain cancer. During his lifetime, Hallett authored more than 1,200 scientific papers, edited nearly 30 books, and was one of the most cited researchers in the world.

Hallett is survived by Judith, his wife of 59 years, his children Nicholas (Brock Monroe) and Victoria (Jeffrey Miller), and grandchildren Celeste Miller and Flora Miller. Born in Philadelphia, Pa., in 1943 to Estelle (nee Barg) and Joseph W. Hallett, an ophthalmologist, Hallett is also survived by his younger siblings, Eileen (Efron) and Bruce.

At Harriton High School in Lower Merion Township, Hallett was senior class president, a champion tennis player, and a beloved summer camp counselor. His public speaking prowess and movie-star looks helped him land lead roles in student productions of The Father of the Bride and Guys and Dolls. The only time he disobeyed his parents was when he decided to leave Philadelphia to attend Harvard College.

Hallett arrived in Cambridge, Mass., with a plan to study astronomy but soon became aware of the controversial experiments with psilocybin being conducted by psychology professors Timothy Leary and Joseph Alpert (Ram Dass). While he did not associate with Leary or Alpert, he began to collect every issue of their journal, The Psychedelic Review. He transitioned from studying the macrocosmic constellations of the universe to the microcosmic networks of the human brain.

He developed another life-long attraction when he met Judith Peller, a fellow Philadelphia native studying in the Boston area. They married just after her graduation from Wellesley College in 1966. The two continued their graduate studies together at Harvard - she earned her Ph.D. in classics while he went on to get his M.D. at Harvard Medical School and completed an internship at Peter Bent Brigham Hospital in Boston.

In 1970, he came to the National Institutes of Health in Bethesda, Md., to serve as a "yellow beret," a joking, self-deprecatory nickname for doctors involved in a research program that simultaneously fulfilled their military service obligations during the Vietnam War. His fellowship in neurophysiology and biophysics in the Laboratory of Neurobiology at the National Institute of Mental Health sparked his interest in the area of motor control. It also introduced him to ongoing research at the Marine Biological Laboratory in Woods Hole, Mass., where he studied giant squid axons and lobster hearts.

Hallett returned to Boston in 1972 to do his residency in neurology at Massachusetts General Hospital. After Nicholas was born in 1974, the family spent a year in England, where Hallett completed a fellowship at the Institute of Psychiatry in London with his mentor C. David Marsden, the world's leading authority on movement disorders.

Hallett became chief of the Clinical Neurophysiology Laboratory at the Brigham, developed a program in movement disorders, and worked his way up to associate professor of neurology at Harvard Medical School. His daughter, Victoria, was born in 1980. The family later moved to Bethesda, where Hallett joined the National Institute of Neurological and Communicative Diseases and Stroke (now called the National Institute of Neurological Disorders and Stroke) in 1984 and created the Human Motor Control Section.

His research centered on the physiology of human movement and motor control, as well as the pathophysiology of different movement disorders. He studied a huge range of topics, including myoclonus (the sudden involuntary jerking of muscles), the pathophysiology of dystonia (involuntary muscle contractions that cause twitching and slow repetitive movements or abnormal postures), and the bradykinesia (overall slowness of movement) experienced by patients with Parkinson's Disease. He pioneered the use of transcranial magnetic stimulation (TMS) to study the central nervous system, and was an early adopter of many technologies and treatments. Hallett also collaborated on the invention of a type of coil for brain stimulation that is patented and FDA approved for the treatment of depression and obsessive-compulsive disorder.

One of his most high-profile patients was internationally renowned classical pianist, Leon Fleisher, who had lost the use of his right hand due to focal, task-specific dystonia, manifested by the involuntary curling of his fingers. Fleisher spent decades playing solely with his left hand. That changed after he was treated by Hallett and his associates with injections of botulinum toxin (Botox) to block the release of the neurotransmitter acetylcholine. This relaxed the abnormally contracting muscles, allowing the fingers to finally release. The New York Times wrote that Fleisher's comeback "catapulted him as a symbol of the human spirit and an inspiration to a broader public."

Hallett later turned his attention to the physiology of free will, a subject he wrote about for both scientific and popular audiences. In a chapter for the book, "Exploring the Illusion of Free Will and Moral Responsibility," he described what he called the salted peanut problem: "You sit in front of a bowl of salted peanuts, and after eating a number of them, you make a conscious decision not to eat any more. Yet, in a very short time, you find that your hand is going out to take some more."

This line of inquiry informed his research into functional neurologic disorders (FND), formerly called "psychogenic disorders." Hallett had seen throughout his career that when patients exhibit movements that appear to be voluntary, but are experienced as involuntary, they often don't get adequate treatment or care. "When I saw that there wasn't anything being published, and no one seemed to understand it, that led me to decide we would study it," he said in a 2023 interview with the Functional Neurological Disorder Society. He helped create that group and served as its inaugural president.

Hallett published extensively on FND, including a 2024 paper about U.S. government officials and family members involved in "Anomalous Health Incidents," aka "Havana Syndrome." It concluded that many of the individuals in the study - who reported symptoms such as dizziness and cognitive dysfunction - were found to have met the criteria for FND.

Hallett has held leadership positions in several other professional organizations including the presidency of the International Federation of Clinical Neurophysiology, The International Parkinson and Movement Disorder Society, and the American Association of Neuromuscular and Electrodiagnostic Medicine. He was also a past vice president of the American Academy of Neurology and served as editor-in-chief of Clinical Neurophysiology and World Neurology and associate editor of Brain.

He received a doctor of medicine honoris causa degree from the University of Hamburg, Germany, in 2017, and was made an honorary member of the European Academy of Neurology in 2018. In 2019, Hallett received the WFN Medal for Contribution to Neuroscience from the World Federation of Neurology and the International Brain Stimulation Award from the Brain Stimulation Journal. He also received the International Association of Parkinsonism and Related Disorders Lifetime Achievement Award.

Despite his incredible list of accomplishments and achievements, Hallett was unfailingly modest and treated everyone with respect. At his NIH lab, where he mentored more than 150 fellows by the time he retired in December 2022, he was known for creating a tremendously supportive atmosphere. They valued his intellect, his encouragement, his kindness, and his humor. In the weeks before Hallett's death, dozens of former colleagues participated in a series of video calls sharing how he had influenced their careers and lives.

So many fellows had children while working for Hallett that the running joke was they were productive and reproductive. He strongly supported finding a work-life balance, which he modeled with his own family. Hallett loved being a father and grandfather, and eagerly built sand castles, skipped stones, and started pillow fights.

Hallett's calming presence made anxieties fade away, and his easy laugh was contagious. Whether he was teaching his kids how to tie their shoe laces or explaining a complex topic to other scientists, Hallett was endlessly patient. And he usually had the perfect "Peanuts" comic strip picked out for the occasion.

A globe-trotter who was regularly on multiple continents each month, Hallett never tired of exploring new places and eating delicious things. Of all of the places he visited, he said that Galapagos was the most memorable. Not only did it offer fascinating wildlife, geology, and history, but also he was accompanied by his entire family. Hallett enjoyed planning grand family vacations almost as much as taking them, and he had hoped to spend much of his retirement relaxing on beaches with Judy. Despite his battle with cancer over the past year, they managed to spend time in the Caribbean and California with kids, grandchildren, and other loved ones.

If you were lucky enough to join Hallett on a trip to one of his regular haunts, he would bring you along for his favorite experiences, such as hearing the jazz band at the Peace Hotel in Shanghai, wandering through the garden of the Four Seasons in Florence, and riding the bike trail to Woody Creek Tavern in Aspen. Even when he was back in Bethesda, he would escape by taking long walks on the path that ran behind the family's house. His granddaughter Celeste called one particularly attractive spot on the route "the end of the world," and as they trekked out there, he would point out how the nature around them shifted with the seasons.

Whenever an image caught his eye, his camera was ready to get to work. Sometimes that was a field of tulips in Holland, a temple in India, or a sunset in St. Thomas. But his favorite subjects were his family members. He was the master of the group shot on a timer, jumping into the frame just in time for the flash.

A memorial service will be held in the spring. In lieu of flowers, donations may be made to the Functional Neurological Disorder Society (fndsociety.org) and the International Parkinson and Movement Disorders Society (movementdisorders.org).