You are currently browsing the category archive for the 'new research' category.
Studies in the past two years have found that people carrying specific genetic variants of the hormone’s receptor are at increased risk of developing autistic traits.
Children with autism have low levels of oxytocin in their blood, and a few small clinical trials have shown that getting extra doses of the hormone can improve some characteristic deficits of the disorder, such as body rocking or interpreting emotion from faces and words. Oxytocin is considered a pretty safe drug, because it doesn’t last long in the body and its effects are short-lived.
On 15 February, French researchers showed for the first time that inhaling small doses — three puffs per nostril — of the hormone can also improve social behaviors, the Holy Grail for autism treatments.
In one experiment, a computer ball-tossing game, participants with autism have more interactions with cooperative virtual partners, and report that they trust them more, after inhaling oxytocin. Similarly, when looking at pictures of faces, oxytocin increases the time participants spend looking at the eyes, which they normally avoid.
The results are based on just 13 adults with high-functioning autism or Asperger’s syndrome, though, so it’s not clear whether they would hold in a larger autism population, or in children with the disorder.
Even so, these are arguably the most exciting results of an autism treatment to date, and should encourage companies to place their trust in oxytocin.
Canines and humans get many of the same diseases, and often respond to the same drug treatments. Dogs also tend to mimic the symptoms and pathology of human disease much more closely than rodents do.
“Understanding the underlying genetics in dogs is almost certain to enlighten us about the human condition,” notes Elaine Ostrander, chief of the Cancer Genetics Branch at the National Human Genome Research Institute.
Because dogs are purposely inbred for specific traits and are extremely well characterized, scientists have long used their pedigrees to study cancer and other biological diseases. But researchers are just beginning to use dogs as models of psychiatric and behavioral conditions, including obsessive-compulsive disorder (OCD) and autism.
In a January report, for instance, scientists pinpointed a genetic hotspot for compulsive behavior by screening a conspicuous subgroup of Doberman Pinschers: those that repetitively suck their flanks. The findings were published in Biological Psychiatry.
The gene may also drive compulsive behaviors in other dog breeds and other species, the researchers say.
“We think this gene will also be the same one involved in human OCD,” notes investigator Nicholas Dodman, director of the animal behavior clinic at Tufts University in Massachusetts. “This is really just the beginning of using [dog] behaviors to study behaviors of humans.”
You may think the simplest explanation is economics. And it’s true that, compared with white families, Hispanic families are less likely to have health insurance and a regular doctor, and more likely to fall below the poverty line.
But the autism disparity remains even when researchers account for those socioeconomic differences, according to a study out this month in the American Journal of Public Health.
The deletion, known briefly as 16p, covers a 25-gene stretch of chromosomal region 16p11.2. It crops up in roughly 0.6 percent of all cases of autism. Some studies have found the variant in individuals with other psychiatric conditions, such as schizophrenia and bipolar disorder, and even in healthy controls.
The new reports are the first to search for obesity-related rare variants across the genome and the first to link 16p — or any other rare DNA deletion or duplication — to obesity.
“The contribution of [rare variants] to obesity, just like for autism and schizophrenia, may be much more important than has been anticipated thus far,” says Jacques Beckmann, chair of medical genetics at University of Lausanne in Switzerland, and lead investigator of one of the new studies. “We should not ignore it.”
One of the studies also finds, for the first time, that oxytocin regulation in people with autism is partly controlled by epigenetic changes, which can turn genes on or off without altering the underlying code.
Oxytocin has been linked to autism for nearly two decades, and the hormone is already being doled out in several small clinical trials to treat the disorder. But the new reports are part of a growing wave of interest in the precise nature of its involvement.
“The field is really new,” says Sue Carter, professor of psychiatry at University of Illinois at Chicago, who was not involved in either new study.
Researchers have previously found significant associations between particular oxytocin-related variants and autism, but how these variants alter the hormone’s production or interact with other genes and developmental influences is unclear, Carter says. “At this point, we’re working with fragments of knowledge, but the fragments we have are remarkably consistent.”
The close-ups are so striking, they made the cover of the 11 January Journal of Cell Biology.
To capture this pretty picture, the researchers used a complex technique called electron cryotomography. They first froze rat brain cells in action at temperatures as low as -165 degrees Celsius, then looked at the cells at different angles using an electron microscope and, finally, reconstructed them in three dimensions on a computer.
There are other methods to look at synapses, but they require cells to be fixed in chemicals for a long time, which can distort the final product. Light microscopy, a much older and more popular technique, illuminates living cells, but only down to 400 nanometers.
Electron cryotomography seems to beat all of these: its flash-freezing preserves the cell’s structure, and its resolution is 5 nanometers — the size of a few dozen atoms.
The technique reveals the workings of some of the tiny protein filaments scattered across a synapse, whose role had been largely unknown before. One type of filament, dubbed ‘tethers’, anchors synaptic vesicles — the bubble-like structures that shuttle chemical messengers inside the cell — to the cell membrane. That way, when the cell receives the appropriate electric signal, the vesicles are in the right position to release the chemicals into the synapse.
“Suddenly amid the sadness, spiritual darkness and depression, his brain seemed to catch fire . . . like lightning. These glimmerings were still but a premonition of that final second (never more than a second) with which the seizure itself began. That second was, of course, unbearable.”
So wrote Fyodor Dostoevsky in his 1868 novel, The Idiot, describing the seizures suffered by his protagonist. Scientists still don’t know much about what causes these debilitating storms of unchecked electrical activity in the brain. Although many childhood neurological disorders involve seizures, “we don’t have a real handle, developmentally, on models to study them,” notes Gordon Fishell, PhD, professor of cell biology.
But that could be changing. Dr. Fishell and his team have created one such childhood epilepsy model by disrupting the development of specific types of brain cells, called interneurons, in mice. Their findings could offer valuable insights for designing drugs to treat these disorders, which afflict some 123,000 children in the United States each year. “These cells restrict electrical activity in the brain, which, when unrestricted, causes seizures,” explains Dr. Fishell, whose work is funded, in part, by the Simons Foundation. “If we could develop drugs that stimulate those particular cells, we might be able to repress seizure activity.”
The latest issue of the Journal of the American Medical Association holds two studies about obesity trends in the U.S. Their basic finding: the rates are slowing down a bit, bit they still ain’t good. Two-thirds of adults, and one-third of children, are overweight or obese.
Obesity, writes J. Michael Gaziano in a related commentary, constitutes the fifth phase of the epidemiologic transition. That’s a mouthful, I know, but he writes a really fascinating (and brief) history of human disease. Here’s a snippet:
Read the rest of this entry »
Courtesy: U. of Washington Institute for Learning & Brain Sciences
In typical conversation, people speak at a rate of 250 milliseconds per syllable. So imagine how confusing it would be if you lagged behind — even if only by a fraction of a second.
That tiny delay may be what’s provoking the language problems in some children with autism.
Tim Roberts, a radiologist at the Children’s Hospital of Philadelphia, has been studying the phenomenon for the last decade. He uses magnetoencephalography, or MEG, the ‘hair dryer’ brain imaging method that uses magnetic fields to detect changes in brain activity on the order of 10 milliseconds or less.
Last week, his team reported that when listening to tones of different frequencies, children with autism give brain responses in their right hemispheres about 11 milliseconds slower than healthy controls do. In other, unpublished work, Roberts found a much longer delay — about 50 milliseconds — when children with the disorder process speech sounds, such as ‘ah’ or ‘ou’.
The average age of children in the study was 10 years. If the findings are similar in babies and toddlers with autism, Roberts says this lag measurement may be a reliable marker for diagnosing the disorder, even before other symptoms appear.
MEG would be particularly useful for young children because it’s non-invasive and doesn’t require them to perform a difficult task. On the downside, a MEG scan isn’t a realistic option for the majority of children with autism — there are only about 100 machines worldwide.
Children with autism have gastrointestinal problems, and special diets can help resolve these issues.
That idea is all but accepted as fact by parents, advocates and scientists alike. Many parents of children with autism report that the children have frequent stomachaches, constipation or acid reflux, and some attribute these to problems digesting gluten or dairy proteins.
In a review published Monday in Pediatrics, a large and diverse group of pediatric experts states unequivocally that there is no evidence to support the idea of autism-specific gut problems or of a so-called ‘leaky gut’ that doesn’t allow children with the disorder to properly digest nutrients.
The journal periodically publishes these consensus reports to try to address controversial issues in an objective way, and to help guide physicians in making good diagnoses and treatment plans. For this one, the panel included 28 clinicians with expertise in, among other things, child psychiatry, epidemiology, allergies, nutrition and pain.
The group’s ultimate recommendation is to treat gut problems in children with autism as you would treat them in any child. The only difference between the two groups may be in how the child responds: a stomachache may make a typical child a bit cranky, but provoke more severe outbursts in a child with autism.
The panel doesn’t rule out the possibility that future research might uncover autism-specific gut problems, pointing out that studies to date are somewhat difficult to interpret. For instance, one study estimates that more than 70 percent of children with autism have gastrointestinal troubles, whereas another pegs that number at a paltry 9 percent.
The panel recommends that studies focus on more precisely calculating this prevalence, rather than on investigating gut issues as root causes of the disorder rigorously designed studies to more precisely calculate this prevalence and to investigate gut issues as root causes of the disorder.
In the meantime, the experts say it’s best to avoid the special diets pushed by the alternative medicine community. They have shown no benefit to children with autism, they note, and, if taken to extremes, could result in harmful malnutrition.
(Edited 1/9, thanks to comment from MJ)
