Near the end of one of his many videos, which can be seen on your local public television station or YouTube, the psychiatrist Daniel Amen tells what he calls his “favorite story.” It has to do with his daughter, Breanne, who, Dr. Amen says with sadness in his voice, “I never thought was very smart.”

“One night,” Dr. Amen tells his rapt studio audience, “she came to me and she said, ‘Dad, I don’t think I can ever be as smart as my friends.’ And it broke my heart. Next day, I scanned her at the clinic.” This means that he subjected her to single photon emission computed tomography, or SPECT, which uses a radioactive isotope to measure blood flow in the brain. “And I’m like, ‘Oh my God!’ I cried when I saw this, because it indicated she had really low energy, really low blood flow in her brain.

“I knew how to fix it,” Dr. Amen continued. “The next day on just a little bit of targeted medication she was much better. Three months later, this girl who never got an A in her life, it was straight A’s! The next 10 years, straight A’s!”

It’s a sweet story, a clincher anecdote of the sort that has made Dr. Amen perhaps the best-known—as well as arguably the most controversial—psychiatrist in the nation. Over the years, he has built a psychiatric empire, with a chain of six Amen Clinics across the country, a steady stream of mega-selling books, a substantial media arm that produces programs shown on PBS member stations nationwide and a business promoting and selling proprietary nutritional supplements. It would be remarkable for any doctor to achieve the degree of notoriety that belongs to Dr. Amen. But what is perhaps most striking about his remarkable success is that it is built on claims, most notably the extraordinary, near-miraculous benefits of SPECT, which have been dismissed as medically worthless by a veritable who’s who of eminent, mainstream psychiatrists, neurologists and brain-imaging specialists.

SPECT is “spectacularly meaningless,” Daniel Carlat, professor of psychiatry at Tufts University, told The Washington Post in 2012. “Basically he’s conning people,” Jeffrey Lieberman, head of the psychiatry department at the Columbia College of Physicians and Surgeons, told me in a recent interview at Columbia Presbyterian Hospital, expressing a sentiment that I heard from at least a half dozen other specialists I interviewed at major universities and research institutions.

Dr. Amen “charges patients thousands of dollars to inject them with radioactive compounds and show them pretty colored pictures of their brains without any credible evidence that it adds to the diagnostic or treatment processes,” wrote Dr. Harriet Hall, a former Air Force flight surgeon and a prominent blogger on medical questions.

Dr. Amen is well aware of critiques like that, and he mounts an energetic defense: “I would offer that most of the people you talked to are not SPECT experts,” he told me in an email, “but rather experts in other imaging modalities, so they are unlikely to really know the scientific literature.” He also provided references to other experts who support his work and several studies that, he says, validate the claims that he has made. “We make diagnoses with all of the information, not just scans,” he said. “But when you add the scans, it changes what physicians do 8 times out of 10.”

Dr. Amen “charges patients thousands of dollars to inject them with radioactive compounds and show them pretty colored pictures of their brains without any credible evidence that it adds to the diagnostic or treatment processes,” wrote Dr. Harriet Hall.

But perhaps the most surprising thing about the prominence and celebrity (and wealth) that Dr. Amen has achieved over the past decade or so is the key, indispensable role played in his rise by the Public Broadcasting Service. Since 2008, a vast majority of the 350 PBS member stations across the country have regularly used one or another of Dr. Amen’s programs, almost always as part of their regular fundraising drives. A PBS spokesperson, Jan McNamara, told me, “PBS is not in a position to track and distribute data or comment on programming that we do not distribute.” But Dr. Amen told The Washington Post in 2012 that the number was around 50,000 total broadcasts—and no doubt the figure is much higher now.

“We broadcast Dr. Amen’s programs because they enjoy wide popularity among our viewers,” Kellie Castruita Specter, senior director for communications and marketing at Channel 13 in New York, wrote by email. “We understand that some medical professionals express reservations about his methods, and there are also some people who claim to have been cured by those same methods. Like many of the programs we carry, we broadcast them, and we allow the audience to judge for themselves.”

There would seem to be two questions in this sense. One has to do with the scientific-medical debate over the effectiveness of SPECT, and the claims Dr. Amen makes for his nutritional supplements, which many specialists dismiss as being nothing more than a 21st-century version of snake oil. The other issue has to do with the role PBS has played in giving both tremendous exposure to Dr. Amen as well as a stamp of approval that has the effect of validating his claims. Specter says that viewers can decide for themselves, but there seems little evidence that either PBS itself or the member stations that air his programs provide much in the way of information to enable viewers to make that judgment. The shows are both publicized and broadcast without a hint of the controversy surrounding Dr. Amen.

[youtube https://www.youtube.com/watch?v=4qRHM8N168w&w=560&h=315%5DThe news here is that nothing has changed. Eight years ago when PBS stations began airing Dr. Amen’s programs, Robert Burton, M.D., the former chief of neurology at Mount Zion Hospital at the University of California in San Francisco, watched unbelieving as Dr. Amen told his studio audience, “I will show you how to make your brain great, including how to prevent Alzheimer’s disease.” Dr. Burton, sharing the consensus that there was no known, clinically proven way to prevent Alzheimer’s disease, subsequently complained on Salon that PBS “broadcast what amounts to an unregulated infomercial for Amen’s unproven treatments.”

Dr. Amen still claims that, using SPECT, he is able to detect Alzheimer’s disease years before symptoms occur and that he has a way of delaying its onset. “SPECT can change the Alzheimer’s epidemic,” he declared.

But several respected neurologists consulted by the Observer protest that there is no convincing evidence that this is true. “Even if the SPECT part of it was true, we absolutely don’t have any intervention to forestall the disease at this time,” said Dr. Howard Feldman, the director of the government-funded Alzheimer’s Disease Cooperative Study, whose purpose is precisely to test the effectiveness of new compounds and drugs. Meanwhile, paradoxically, Dr. Amen’s reputation, practice and businesses all continue to grow, enhanced by his continued appearances—with not a contrary word uttered on air—on PBS stations across the country.

Daniel Amen is a slight, balding, 62-year-old with a friendly demeanor and a telegenic smile. He appears on his programs, which he produces in conjunction with High Five Entertainment in Nashville, talking in front of a studio audience. He usually wears a casual red knit pullover or a dark sports coat over a dark T-shirt, speaks eloquently and passionately, with just a tinge of valley girl syntax (“And I’m like, ‘Oh, my God!’ ”) to give him a common touch. He went to a small evangelical Christian college in California, spent three years in the Army after high school as an X-ray technician and received his medical degree from the now defunct Oral Roberts Medical School (the school’s namesake was an Elmer Gantry-like television evangelist).

“Psychiatry is the only specialty that doesn’t actually look at the organ it treats,” is a standard line he uses to introduce SPECT. “Imaging,” Dr. Amen said, “helped me see the underlying biology behind the symptoms.”

SPECT is mania with him. Over the years, he says, he’s accumulated the world’s largest collection of SPECT scans, with over 115,000 in his collection. After a young man has been dating one of his daughters for a few months, he makes the suitor undergo a SPECT scan. During all of his talks, he projects SPECT images on a screen. The healthy, “beautiful” brains are perfect ovals, cream-colored fading to violet and as smooth as marble. The “unhealthy,” diseased, traumatized brains are wrinkled and rumpled, a bit like hooked rugs. The brains of Alzheimer’s victims, a dramatic part of Dr. Amen’s presentations, are shriveled, riddled with holes; they look like meteor fragments fallen to earth.

In fact, as brain-imaging specialists will tell you, actual brains, even the brains of Alzheimer’s sufferers, do not have gaping holes in them; no living person’s brain is rumpled like a piece of corrugated metal. “He puts these images on screens in his talks without explanation, implying that this is a photographic likeness to the person’s brain,” Mark Slifstein, an associate professor in the department of psychiatry at Columbia University, told me. “It is not.”

But however Dr. Amen presents his scans, the more important point is the claims he makes for them. On Alzheimer’s, for example, he tells his studio audiences that the disease shows up in the brain 30 to 50 years before the onset of symptoms. Therefore, “You should be scanned early because treatment should be early.” He talks about former National Football League players suffering from brain damage, and he asserts that SPECT served as a crucial tool to diagnosing their injuries. He says that by putting these former players on a “smart program,” 80 percent of them were able to “rehabilitate their brains.” He boasts that SPECT images have enabled him to detect five specific brain patterns associated with being overweight. He contends that SPECT can help spot schizophrenia, depression and seven distinct forms of attention deficit hyperactivity disorder, or ADHD, and, since he can tailor his treatment to the type, he claims success in 9.5 out of 10 cases.

But these kinds of claims are exactly what arouse outrage from many brain specialists. Dr. Lieberman, a former president of the American Psychiatric Association, likens Dr. Amen’s use of SPECT to the 19th-century fad for phrenology, by which the size and shape of the skull were said to be measures of a person’s intelligence and personality. Dr. Amen’s use of those multihued images is “pseudo-color phrenology,” Dr. Lieberman charged. “What he does is present himself as practicing a new self-discovered form of psychiatry using a journeyman imaging technique—SPECT—to make diagnoses and select treatments,” he said. “There is absolutely no scientific evidence for what he says and does.”

“Theoretically it would be great if you could do a scan and use it to make a diagnosis,” Dr. Carlat of Tufts told me. “But the key point is that it’s all theoretical. There haven’t been any convincing studies at all that you can diagnose conditions that Dr. Amen says you can diagnose.” Dr. Carlat said he applauds Dr. Amen for some things, notably “bringing natural healing into his practice,” emphasizing things like nutrition, sleep and lifestyle as elements in psychological well-being. “But to the extent that he’s leading people to the false premise that you can use SPECT images to get a diagnosis, that’s where he verges on being a charlatan.”

SPECT technology uses a radioactive isotope injected into the bloodstream to measure blood flow in the heart or the brain. There was great excitement about the technology when it was first developed more than 30 years ago, but it was superseded and largely replaced by other scanning techniques, such as positron emission tomography (PET) or magnetic resonance imaging (MRI), which are both more advanced and, in the case of MRI, does not involve injecting radioactive materials into the bloodstream. Most specialists I talked to said it isn’t used much at all any more, though it is capable of helping to detect conditions like strokes, tumors and a rare form of Alzheimer’s disease known as front temporal dementia.

“It doesn’t have the resolution to give information pertaining to anything beyond these very dramatic conditions,” Dr. Lieberman said. “The images have zero relevance to mental disorders.”

“All of my career has been working with brain images of people with psychiatric conditions, including schizophrenia, depression, substance abuse, obsessive compulsive disorder, anorexia and bulimia, as well as people who do not have psychiatric conditions, and for the most part there are simply no visual differences among them,” Columbia’s Dr. Slifstein said. “The idea that you could diagnose any of these conditions in a single person by visually inspecting a SPECT blood-flow image is highly dubious.”

In 2010, two specialists at the Brain Imaging Council of the Society for Nuclear Medicine, Bryon Adinoff and Michael Devous, wrote in The American Journal of Psychiatry that several years earlier they had “offered to Dr. Amen the opportunity to submit his analyses of a blinded set of SPECT scans to determine how effective his technique is at correctly diagnosing subjects.” They said that in two decades, Dr. Amen never accepted that challenge, and yet “he has persisted in using scientifically unfounded claims to diagnose and treat patients.”

He contends that SPECT can help spot schizophrenia, depression and seven distinct forms of attention deficit hyperactivity disorder, or ADHD, and, since he can tailor his treatment to the type, he claims success in 9.5 out of 10 cases.

Asked about that, Dr. Amen told me by email, “I have never actually been asked,” though the text of the article in a major professional journal would seem to indicate that he has been asked. More generally, he argued that by sticking with SPECT and developing it, he has pioneered a diagnostic tool that the psychiatric establishment has been stubborn and foolish to ignore. “I have my share of critics,” he acknowledged, “but pressed on because our work changes lives, and that has always been the driving factor.” Moreover, he does have support among some other professionals—or he does up to a point. The Observer interviewed four doctors—psychiatrists or other specialists, all of them highly credentialed—whose names were provided by Dr. Amen, and all contended that SPECT is far more useful and far more promising than most specialists recognize.

“There is a lot of evidence that SPECT, if it is done with appropriate equipment and read by an appropriate reader, by measuring specific patterns of blood flow can be helpful in diagnosing dementia,” Andrew Newberg, a nuclear medicine specialist at Jefferson University Hospital in Philadelphia, explained by phone. Another specialist, Rob Tarzwell, a clinical assistant professor on the faculty of medicine at the University of British Columbia, co-authored a paper with Dr. Amen and Newberg showing that SPECT was useful in distinguishing between traumatic brain injury and post traumatic stress disorder (PTSD), a development that Discover magazine called one of the 100 top science stories of 2015.

“Ultimately, it doesn’t matter whether Dan’s specific patterns stand or fall,” Dr. Tarzwell concluded. “What matters is bringing a new diagnostic tool to maturity in psychiatry, where diagnostic tools are few and far between, and I think the discoveries Dan has made in a preliminary way are now on the cusp of being properly validated, or else properly refuted. It’s incredibly exciting.”

But while these specialists praised Dr. Amen, they all also acknowledged that he overstates his case, particularly on the television programs by which he spreads his message. They attribute this benignly to Dr. Amen’s sincere conviction that SPECT is vastly more beneficial than most experts realize.

Still, even his supporters stress what they describe as SPECT’s potential more than they do its established value. No expert that I talked to, for example, was convinced that SPECT can detect Alzheimer’s Disease years before the onset of symptoms, as Dr. Amen contends.

Dr. Amen has authored or co-authored numerous articles in professional journals, some of which he provided to me, presenting them as studies that confirm his claims. Among them, for example, is a recent paper in the Journal of Psychoactive Drugsshowing that in 30 cases of brain damage in former football players, a SPECT analysis combined with nutritional supplements produced “statistically significant increases in scores in attention, memory, reasoning, information processing, speed and accuracy.”

If that is true, it would be a major development, since what Dr. Amen is saying is that by using SPECT and his cocktail of nutritional supplements he has found an effective way to reverse brain damage. “Using all of our strategies, not just supplements, I sincerely believe and demonstrate in our clinics, that we can reverse brain damage,” Dr. Amen proclaimed by email. “I have shown it repeatedly.”

“Dr. Amen’s use of multihued images is ‘pseudo-color phrenology’…There is absolutely no scientific evidence for what he says and does.”—Dr. Jeffrey Lieberman, head of the psychiatry department at the Columbia College of Physicians and Surgeons

To his supporters, studies like the one on the football players, even if small, show at least that SPECT is an important, underutilized tool. What Dr. Amen’s critics don’t see, Dr. Tarzwell said, is that in the next five to 10 years, the resolution achieved by SPECT will improve greatly, and it will be able to do exactly what Dr. Amen said he does with it—see the physiology behind the psychological symptoms, detect disorders that don’t show up in the usual symptoms. “I’d rather have a guy like Daniel Amen overselling it than for us to just shout into the abyss,” he said.

But while the study showing such good results in reversing brain damage might convince a lay audience watching PBS, professionals maintain that it has no scientific validity or clinical value, mainly because it was done with no control group, so it is impossible to know whether the improvements measured by Dr. Amen were due to SPECT and supplements or to a placebo effect, which is often very powerful.

“Normally you would evaluate a person without SPECT and then do an evaluation with SPECT and show a difference, but that’s not what was done in this case,” a senior scientist at the National Institutes of Health who requested anonymity told the Observer. “They don’t show that SPECT was any better than good clinical judgment.” The damage-reversal study was an open-label one, meaning that the former football players who were its subjects knew that they were taking supplements and not a placebo. “Nothing can be concluded from such studies,” Dr. Paul Aisen, a neurologist at the Keck School of Medicine at USC and one of the country’s leading Alzheimer’s researchers, concluded after reviewing the studies that Dr. Amen had shown the Observer. “They show no meaningful evidence in favor of SPECT scanning or nutritional supplements.”

And then there are those nutritional supplements themselves, which Dr. Amen sells online, claiming that they benefit healthy people as well as brain-damaged ones, but here even the people he designated to speak on his behalf expressed skepticism. “I don’t use supplements in my practice,” Dr. Tarzwell said. “There isn’t much data in terms of large, randomized trials,” Dr. Newberg told me, speaking of supplements in general. “That’s in part because many doctors are biased against supplements, but even so there are small studies showing potential benefits.”

Dr. Amen himself is vague in his television programs on what exactly he prescribes for patients—using phrases like “targeted medication,” “dopamine boosters” or “smart programs,” rather than specify exactly what medication his patients are taking. But as his study of football players shows, he relies a great deal on supplements, more or less like the “BrainMD” products he promotes and sells on his website—consisting of substances like multivitamins, ginkgo biloba extract, omega-3 fatty acids, a moss extract known as Huperzine A and another 50 or so ingredients. “This is one of the best brain health supplements available,” Dr. Amen exclaims on his website, “offering support for a wide range of cognitive functions, including focus, memory and mental clarity.”

There’s always some buzz about one or another supplement—remember the Nobel Laureate Linus Pauling’s claims for vitamin C, or the belief that garlic pills will keep you healthy. Over the years, scientists at research institutes have tested substances like St. John’s Wort for depression and ginkgo biloba and Huperzine A for Alzheimer’s Disease. Dr. Amen seems especially fond of ginkgo, saying in one of his programs, “The prettiest scans I’ve ever seen are from people who take ginkgo.”

But the experts who find his SPECT claims unfounded feel the same way about his supplements. Dr. Aisen of USC recalled, for example, a study of ginkgo extract that showed some possible benefit in slowing Alzheimer’s, but, he said, “the study wasn’t replicated, and nobody I know would prescribe it.” More generally, Dr. Aisen said, “There is no study showing any benefit of any of these things in normal people.”

“A lot of them have been tested,” Dr. Feldman of the Alzheimer’s Disease Cooperative Study told me, referring to the ingredients in Dr. Amen’s BrainMD product. “Unfortunately none of them has withstood the test of clinical effectiveness.”

The way Dr. Amen’s programs are presented and used by PBS amount to an unqualified, if implicit, endorsement.

But that’s the sort of expert opinion you won’t see on PBS. Indeed, the way Dr. Amen’s programs are presented and used amount to an unqualified, if implicit, endorsement of Dr. Amen himself and his claims. The stations, for example, give away his books and videos in exchange for donations. For $90, you get a DVD of the pledge program plus a copy of Dr. Amen’s best-selling book, Change Your Brain, Change Your life: The Breakthrough Program for Conquering Anxiety, Depression, Obsessiveness, Lack of Focus, Anger, and Memory Problems. For a $240 pledge, the gift is the book plus Dr. Amen’s Change Your Life DVD.

Dr. Amen “gives very specific steps to boost your mood, focus and memory and decrease your risk for Alzheimer’s Disease,” intoned the publicity that KCTS in Seattle put out on its website this spring in advance of airing Dr. Amen’s newest program. I saw the KCTS broadcast, which was accompanied by a separate interview with Dr. Amen that can only be described as fawning. (Efforts to get someone at the station to comment were unavailing.) And then there’s always that tagline reiterated at some point by the station host: “This is the kind of programming you can only get on PBS.”

Dr. Amen told me that he receives “a small percentage, less than 25 percent” of the donations received by the stations airing his programs, which, he said, covers his production and distribution costs. That’s a pretty good deal. The PBS stations, limited in the amount of advertising they can sell directly, depend on member donations, which they use for such quality programs as Nova, Frontline and others. By using Dr. Amen’s programs for fundraising they are engaging in a kind of indirect advertising, during which Dr. Amen, in his hour-long studio appearances, can promote himself, his methods and, indirectly, his nutritional supplement business without having to label this promotion as advertising or to suffer any contrary opinions.

These services and products, moreover, don’t come cheap. An initial consultation at one of Dr. Amen’s clinics costs $400. A SPECT examination, consisting of two scans, one at rest and one while concentrating, costs $3,950, which most medical insurance does not cover. During a visit to Amen Clinics’ New York branch, I was told that 85 to 90 percent of patients elect to have SPECT scans, with many of them first hearing about the technique on PBS. Dr. Amen’s mid-range nutritional supplement, called “Brain and Body Power,” sells for $84.96 a month if you elect automatic monthly shipments.

This spring, stations from WNET in New York to KPBS in San Diego broadcast Dr. Amen’s latest video, On the Psychiatrist’s Couch, whose refrain is, “You’re not stuck with the brain you have; you can make it better.” In the advance publicity on their websites, these stations frequently cite a 2012 article in The Washington Post to the effect that “Daniel Amen is the most popular psychiatrist in America.” The publicity neglects to mention the second half of the headline on what was actually a highly critical Washington Post profile: “To most researchers that’s a very bad thing.”

Richard Bernstein, a former reporter and critic at The New York Times, is the author of China 1945: Mao’s Revolution and America’s Fateful Choice. Follow him on twitter: @R_Bernstein