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Archive for Neuroscience/Mental Health

The Increase in Autism Diagnoses: Two Hypotheses

A new study sheds more light on the question of what is causing the recent increase in the rate of diagnosis of autism. Professor Dorothy Bishop from the University of Oxford studied adults who were diagnosed in 1980 with a developmental language disorder. She asked the question – if these people were subjected to current diagnostic criteria for autism, how many of them would be diagnosed today as having autism? She found that 25% of them would. (Bishop 2008)

This epidemiological question has been at the center of a controversy over whether or not there is a link between vaccines (or the mercury-based preservative, thimerosal, that was previously in routine childhood vaccines) and autism. The primary evidence for this claim put forward by proponents of a link is that the number of diagnoses of autism increased dramatically at the same time that the number of vaccines routinely given to children was increasing in the 1990′s. They are calling this rise in autism an “epidemic” and argue that such an increase requires an environmental factor, which they believe is linked to vaccines.

That the number of new autism diagnoses is dramatically increasing is generally accepted and not a point of debate. The historical rate of autism is about 4 per 10,000 and the more recent estimates are in the range of 15-20 per 10,000 (30-60 per 10,000 for all pervasive developmental disorders of which autism is one type). (Rutter 2005) The controversy is about what is causing this rise in diagnoses. There are two basic hypotheses: 1) That the true incidence of autism is rising due to an environmental cause, 2) That the rise in incidence is mostly or completely an artifact of increased surveillance and broadening of the definition of autism. These two hypotheses make specific predictions, and there is much evidence to bring to bear on their predictions – this recent study only being the latest.

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Posted in: Neuroscience/Mental Health, Public Health, Vaccines

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SPECT Scans at the Amen Clinic – A New Phrenology?

Phrenology was a 19th century pseudoscience that claimed to associate brain areas with specific personality traits. It was based on palpating bumps on the skull and was totally bogus. New brain imaging procedures are giving us real insights into brain function in health and disease. They are still blunt instruments, and it is easy and tempting to over-interpret what we are seeing. In his book The New Phrenology William Uttal warns that “the excitement of these new research tools can lead to a neuroreductionist wild goose chase” and that we must be careful not to succumb to new versions of the old phrenology.

The Amen Clinics, founded by Daniel G. Amen, MD, offer SPECT (single photon emission computed tomography) scans to help diagnose and manage conditions such as attention deficit disorders (ADD), mood disorders, anxiety and panic disorders, autistic spectrum disorders, obsessive compulsive disorder (OCD), substance abuse, toxic exposure, brain trauma, memory problems, temper problems, and relationship and marital struggles.

The scans generate colored pictures of the brain that show “areas of your brain that work well, areas that work too hard, and areas that do not work enough.” They do not actually provide a diagnosis, but “must be placed in the context of a person’s life, including their personal history and mental state.” “The goal of treatment is to balance brain function, such as calm the overactive areas and enhance the underactive ones.” (more…)

Posted in: Medical Ethics, Neuroscience/Mental Health, Science and Medicine

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Cell Phones and Brain Tumors

The question of whether or not there is a link between the use of mobile phones (also called cell phones) and the risk of brain tumors has been cropping up more and more frequently in the media – every time a new study or analysis comes out. This is a very important question of public health as cell phone use is becoming more common, and brain tumors are a very serious and often life-threatening category of diseases.

Of course such questions are best answered by a dispassionate, careful, and systematic look at the science – what is the plausibility of a link and what is the evidence that there actually is one. At this point we are somewhere in the middle of studying this problem. We already have substantial data, but it is conflicting and the research community is still debating on how to get more definitive data everyone can agree upon. So at present there is a variety of opinions on the matter. The consensus seems to be that cell phones probably do not cause brain tumors, but we’re not sure, there is meaningful dissent from this opinion, and so more study is needed.

There are two types of scientific studies we can do to answer this question. The first is biological and looks at the effects of radiation, and specifically the type and strength of radiation emitted by cell phones, on cells in a test tube and on animals. This will tell us if a risk from cell phones is plausible, if there is a mechanism, and what, if any, the effects are likely to be. But this kind of data will not tell us if cell phones in fact have caused or are causing brain tumors.

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Posted in: Neuroscience/Mental Health, Public Health

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Thoughts on Neuroplasticity

I recently read a fascinating book, The Brain That Changes Itself by Norman Doidge. He describes case histories and research indicating that the brain is far more malleable than we once thought. We used to think each function was localized to a small area of the brain and if you lost that area of brain tissue the function was gone forever. We once thought you couldn’t teach an old dog new tricks. Now we know better. 

Learning a new skill actually changes the structure and function of the brain, even into old age. If you exercise one finger, the area of the brain devoted to that finger enlarges. The old concept of dedicated brain areas for specific functions no longer holds. Areas of the cortex that normally process vision can learn to process totally different inputs such as hearing. This is what happens with blind people: their hearing skills are enhanced when new neural connections for hearing invade the disused visual cortex. They may not actually have better hearing acuity, but they have learned to pay more attention to auditory input and to use it to build up a representation of the world around them.

One of the more intriguing experiments he describes was in monkeys. When sensory input nerves to one arm were severed, the monkey stopped using the arm, even though the motor nerves were intact. When the good arm was put in a sling, the monkey started using the impaired arm again.  When both arms were deprived of sensory input, the monkey used both arms.  (more…)

Posted in: Book & movie reviews, Neuroscience/Mental Health

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Do Antidepressants Work? The Effect of Publication Bias

A recent meta-analysis of the most commonly prescribed antidepressant drugs raises some very important questions for science-based medicine. The study: Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the Food and Drug Administration, was conducted by Irving Kirsch and colleagues, who reviewed clinical trials of six antidepressants (fluoxetine, venlafaxine, nefazodone, paroxetine, sertraline, and citalopram). They looked at all studies submitted to the FDA prior to approval, whether published or unpublished. They found:

Drug–placebo differences in antidepressant efficacy increase as a function of baseline severity, but are relatively small even for severely depressed patients. The relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication.

The press has largely reported this study as showing that “antidepressants don’t work” but the full story is more complex. This analysis certainly has important implications for how we should view the body of evidence for these antidepressants. It also illuminates the possible role of publication bias in the body of scientific literature – something that has far ranging implications for science-based medicine.

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Posted in: Clinical Trials, Neuroscience/Mental Health, Pharmaceuticals, Science and Medicine

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Science by press release: A helmet to fight Alzheimer’s disease?

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Recently, I’ve had a number of people bring to my attention a news story that has apparently been sweeping the wire services and showing up in all sorts of venues. It is, on its surface, a story of hope, hope for the millions of elderly (and even the not-so-elderly) who are or will be afflicted by that scourge of the mind, memory, and personality, Alzheimer’s disease. This disease is one of the most feared of diseases. A progressive and fatal disease of the brain, it robs a person of his memory and personality, until he no longer recognizes loved ones and becomes too demented to care for himself. The pathophysiology involves the accumulation in the brain of a protein known as β-amyloid, which forms plaques outside of cells, while neurofibrillary tangles believed to be due to the hyperphosphorylation of a protein known as tau develop in dying cells. The exact mechanism by which neuron death occurs is not fully understood, but over time this process leads to a decrease in the amount of gray matter in the cortex. There is no known cure, and the current treatments that we have result in at best a modest delay of the inevitable dementia that accompanies progression of the disease.

Given this grim backdrop and the general aging of the population in developed nations, it is expected that there will be a large increase in the number of people developing Alzheimer’s disease over the next few decades. Naturally, this provides a great deal of incentive to develop more effective treatments. Not surprisingly, sometimes the treatments proposed may sound somewhat outlandish and may even be somewhat outlandish. The treatment about which people were e-mailing me falls into this category, and I haven’t decided yet whether it’s science or pseudoscience. It could be legitimate. What I do know, however, is that I don’t like the way its inventors are promoting it by press conference before any evidence of its clinical efficacy in humans has been accepted by a peer-reviewed publication, leading to a flurry of stories about a new possible “miracle cure” for Alzheimer’s disease grounded in not a lot of science. I’m referring, of course, to the “Alzheimer’s helmet” developed by Dr. Gordon Dougal and his colleagues Dr. Paul Chazot and Abdel Ennaceur at Durham University. Dr. Dougal is a director of Virulite, a medical company based in County Durham in the U.K. Here’s a widely cited article from the Daily Mail that describes the device:
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Posted in: Basic Science, Medical devices, Medical Ethics, Neuroscience/Mental Health, Science and Medicine, Science and the Media

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Itching and the Imaginary Passenger Brake

The press and government agencies ally to shine a disproportionate amount of publicity on false and improbable medical ideas. (Danger: Congressmen and reporters at work.)

The latest was a press release from either the Centers for Disease Control (and prevention? – I’ll get to the “prevention” part later,) or from Kaiser-Permanente Medical Group. Three Bay Area newspapers carried simultaneous articles. The articles announced a new, $338,000 CDC/Permanente study of something they call “Morgellon’s disease.” I say they call it that because what they are describing is not what was originally described as “Morgellon’s,” but what is most likely a form of somatiform illness – delusional parasitosis, or neurodermatitis.

What is Morgellon’s and why is CDC funding Kaiser/Permanente with $338,000 to study it? I was never taught about anything called Morgellon’s, and althoughI had practiced medicine for forty years, I still had not known of it until several years ago when a group of affected San Francisco patients and R L Stricker MD, were reported as having a number of cases of it.

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Posted in: Neuroscience/Mental Health, Science and Medicine

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Mercury in vaccines as a cause of autism and autism spectrum disorders (ASDs): A failed hypothesis

Blogging on Peer-Reviewed ResearchOne of the most pernicious medical myths of recent years has been the claim, promulgated by a subgroup of parents of autistic children and facilitated by scientists of dubious repute, that somehow the mercury in the thimerosal (ethyl mercury) preservative used in common childhood vaccines in the U.S. until early 2002 causes autism. Although it had been percolating under the radar of most parents and scientists for several years before, this belief invaded the national zeitgeist in a big way in 2005, beginning with the publication of a book by journalist David Kirby entitled Evidence of Harm: Mercury in Vaccines and the Autism Epidemic: A Medical Controversy. The fires of hysteria were stoked even higher by Robert F. Kennedy, Jr., who published a truly twisted and misleading piece of pseudojournalism and pseudoscience published simultaneously in Rolling Stone and on Salon.com entitled Deadly Immunity. Relying primarily on quote-mining of the transcripts of both a conference held Atlanta by the CDC to discuss the question of whether autism is related to thimerosal in vaccines and an Institute of Medicine report on vaccines while simultaneously misrepresenting the results of two studies by Verstaeten et al to paint a false picture of a government coverup, RFK Jr. almost single-handedly managed to stoke fears that vaccines were causing an “epidemic of autism.”

I say “almost” single-handedly, because, unfortunately, he had help. Relying on the dubious research of a variety of investigators, such as the father-and-son team of Dr. Mark Geier and David Geier, whose prodigious output of badly designed studies emanating from a lab in their home in suburban Maryland, done using a rubberstamp institutional review board stacked with friends and cronies to approve the studies, and published for the most part in non-peer-reviewed journals, activists loudly insisted that mercury in vaccines was the cause of most autism. Others claiming to demonstrate this link include Boyd Haley, a chemist from the University of Kentucky, and a few other vocal scientists and advocates, who claim that autism is, in essence, mercury poisoning. Facilitating the dissemination of this message were reporters such as David Kirby, activists such as Robert F. Kennedy, Jr., and media personalities such as Don Imus. Indeed, some activists claimed that some vaccines were “poisoning” our children, even going so far as show photos of autistic children with the label “mercury-poisoned“ underneath them on placards held aloft at protest rallies. They made quite a splash then, and still do to a lesser extent even today. There’s just one problem.
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Posted in: Dentistry, Neuroscience/Mental Health, Public Health, Science and the Media, Vaccines

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