Posts tagged disorders
Articles and news from the latest research reports.
The eyes may be windows into the soul, but following their movement also could allow doctors to make quick, accurate diagnoses for disorders like autism, schizophrenia, or attention deficit hyperactivity disorder, various research projects suggest.
Eye tracking, which records where subjects focus when watching visual displays, could diagnose brain disorders more accurately than subjective questionnaires or medical examinations do, researchers say. Exams are expensive and time-consuming, and subjective tests have been known to wrongly identify healthy people or misdiagnose disorders.
To make sense of all that people see, the brain filters huge amounts of visual information, fills in gaps and focuses on certain objects. That complex task uses many mental circuits, so differences in what people choose to look at ― differences so subtle that only a computer can spot them ― could provide unprecedented insight into common neurological problems.
Every day, we face thousands of decisions both major and minor — from whether to eat that decadent chocolate cupcake to when to pursue a new romantic relationship or to change careers. How does the brain decide? A new study suggests that it relies on two separate networks to do so: one that determines the overall value — the risk versus reward — of individual choices and another that guides how you ultimately behave.
Researchers at the Hebrew University of Jerusalem have discovered that a neuronal pathway — part of the autonomic nervous system — reaches the bones and participates in the control of bone development.
The newly discovered pathway has a key role in controlling bone density during adolescence, which in turn determines the skeletal resistance to fracture throughout one’s entire life, say the researchers. They emphasize that understanding the mechanisms connecting the brain and the bones could have implications for possible future therapies to better deal with osteoporosis and various neural disorders. The findings of the Hebrew University team are published this week in the American journal PNAS (Proceedings of the National Academy of Sciences).
Studying Everyday Eye Movements Could Aid in Diagnosis of Neurological Disorders
USC-led team has designed a low-cost, easily-deployed method for detecting ADHD, Parkinson’s, and Fetal Alcohol Spectrum Disorder
Researchers at the University of Southern California have devised a method for detecting certain neurological disorders through the study of eye movements.
In a study published today in the Journal of Neurology, researchers claim that because Attention Deficit Hyperactivity Disorder (ADHD), Fetal Alcohol Spectrum Disorder (FASD) and Parkinson’s Disease (PD) each involve ocular control and attention dysfunctions, they can be easily identified through an evaluation of how patients move their eyes while they watch television.
“Natural attention and eye movement behavior – like a drop of saliva – contains a biometric signature of an individual and her/his state of brain function or dysfunction,” the article states. “Such individual signatures, and especially potential biomarkers of particular neurological disorders which they may contain, however, have not yet been successfully decoded.”
Typical methods of detection—clinical evaluation, structured behavioral tasks and neuroimaging—are costly, labor-intensive and limited by a patient’s ability to understand and comply with instructions. To solve this problem, doctoral student Po-He Tseng and Professor Laurent Itti of the Department of Computer Science at the USC Viterbi School of Engineering, along with collaborators at Queen’s University in Canada, have devised a new screening method.
Participants in the study were simply instructed to “watch and enjoy” television clips for 20 minutes while their eye movements were recorded. Eye-tracking data was then combined with normative eye-tracking data and a computational model of visual attention to extract 224 quantitative features, allowing the team to use new machine learning techniques to identify critical features that differentiated patients from control subjects.
With eye movement data from 108 subjects, the team was able to identify older adults with Parkinson’s Disease with 89.6% accuracy, and children with either ADHD or FASD with 77.3% accuracy.
Providing new insights into which aspects of attention and gaze control are affected by specific disorders, the team’s method provides considerable promise as an easily-deployed, low-cost, high-throughput screening tool, especially for young children and elderly populations who may be less compliant to traditional tests.
“For the first time, we can actually decode a person’s neurological state from their everyday behavior, without having to subject them to difficult or time-consuming tests,” Itti said.
Vitamin B12 deficiency: Tracking the genetic causes
August 26, 2012
Vitamin B12 is essential to human health. However, some people have inherited conditions that leave them unable to process vitamin B12. As a result they are prone to serious health problems, including developmental delay, psychosis, stroke and dementia. An international research team recently discovered a new genetic disease related to vitamin B12 deficiency by identifying a gene that is vital to the transport of vitamin into the cells of the body. This discovery will help doctors better diagnose this rare genetic disorder and open the door to new treatments. The findings are published in the journal Nature Genetics.
"We found that a second transport protein was involved in the uptake of the vitamin into the cells, thus providing evidence of another cause of hereditary vitamin B12 deficiency", said Dr. David Rosenblatt, one of the study’s co-authors, scientist in medical genetics and genomics at the Research Institute of the McGill University Health Centre (RI MUHC) and Dodd Q. Chu and Family Chair in Medical Genetics and the Chair of the Department of Human Genetics at McGill University. "It is also the first description of a new genetic disease associated with how vitamin B12 is handled by the body".
These results build on previous research by the same team from the RI MUHC and McGill University, with their colleagues in Switzerland, Germany and the United States. In previous work, the researchers discovered that vitamin B12 enters our cells with help from of a specific transport protein. In this study, they were working independently with two patients showing symptoms of the cblF gene defect of vitamin B12 metabolism but without an actual defect in this gene. Their work led to the discovery of a new gene, ABCD4, associated with the transport of B12 and responsible for a new disease called cblJ combined homocystinuria and methylmalonic aciduria (cblJ-Hcy-MMA).
Using next generation sequencing of the patients’ genetic information, the scientists identified two mutations in the same ABCD4 gene, in both patients. “We were also able to compensate for the genetic mutation by adding an intact ABCD4 protein to the patients’ cells, thus allowing the vitamin to be properly integrated into the cells,” explained Dr. Matthias Baumgartner, senior author of the study and a Professor of metabolic diseases at Zurich’s University Children’s Hospital.
Vitamin B12, or cobalamin, is essential for healthy functioning of the human nervous system and red blood cell synthesis. Unable to produce the vitamin itself, the human body has to obtain it from animal-based foods such as milk products, eggs, red meat, chicken, fish, and shellfish – or vitamin supplements. Vitamin B12 is not found in vegetables.
"This discovery will lead to the early diagnosis of this serious genetic disorder and has given us new paths to explore treatment options. It also helps explain how vitamin B12 functions in the body, even for those without the disorder," said Dr. Rosenblatt who is the director of one of only two referral laboratories in the world for patients suspected of having this genetic inability to absorb vitamin B12. Dr. Rosenblatt points out that the study of patients with rare diseases is essential to the advancement of our knowledge of human biology.
Source: medicalxpress.com
The human microbiome: Me, myself, us
Looking at human beings as ecosystems that contain many collaborating and competing species could change the practice of medicine.
A human being is an individual who has grown from a fertilised egg which contained genes from both father and mother. A growing band of biologists, however, think this definition incomplete. They see people not just as individuals, but also as ecosystems. In their view, the descendant of the fertilised egg is merely one component of the system. The others are trillions of bacteria, each equally an individual, which are found in a person’s gut, his mouth, his scalp, his skin and all of the crevices and orifices that subtend from his body’s surface.
A healthy adult human harbours some 100 trillion bacteria in his gut alone. That is ten times as many bacterial cells as he has cells descended from the sperm and egg of his parents. These bugs, moreover, are diverse. Egg and sperm provide about 23,000 different genes. The microbiome, as the body’s commensal bacteria are collectively known, is reckoned to have around 3m. Admittedly, many of those millions are variations on common themes, but equally many are not, and even the number of those that are adds something to the body’s genetic mix.
Holding on to faulty protein delays brain degeneration
When something goes wrong in your brain, you’d think it would be a good idea to get rid of the problem. Turns out, sometimes it’s best to keep hold of it. By preventing faulty proteins from being destroyed, researchers have delayed the symptoms of a degenerative brain disorder.
SNAP25 is one of three proteins that together make up a complex called SNARE, which plays a vital role in allowing neurons to communicate with each other. In order to work properly, all the proteins must be folded in a specific way. CSP alpha is one of the key proteins that ensures SNAP25 is correctly folded.
Cells have a backup system to deal with any misfolded proteins – they are destroyed by a bell-shaped enzyme called a proteasome, which pulls the proteins inside itself and breaks them down.
People with a genetic mutation that affects the CSP alpha protein – and its ability to correctly fold SNAP25 – can develop a rare brain disorder called neuronal ceroid lipofuscinosis (NCL). The disorder causes significant damage to neurons – people affected gradually lose their cognitive abilities and struggle to move normally.
To find out what role proteasomes might play in NCL, Manu Sharma and his colleagues at Stanford University in California blocked the enzyme in mice that were bred to lack CSP alpha. “We weren’t sure what would happen,” says Sharma. Either the misfolded SNAP25 would accumulate and harm the cells, or some of the misfolded proteins may work well enough to retain some of their function.
Longer life
It appears it was the latter. Mice bred to lack CSP alpha suffer the same physical and cognitive problems as humans, and tend to survive for about 65 to 80 days, rather than the normal 670 days. But mice injected with a drug that blocked protease lived, on average, an extra 15 days. “Fifteen days might not sound like much, but as a percentage it’s quite significant,” says Sharma. What’s more, treated mice were able to stave off measurable movement and cognitive symptoms for an extra 10 days.
The finding goes against the idea that neurodegenerative disorders should be treated by clearing away misfolded proteins, rather than trying to rescue their function. “People normally think that protease isn’t working hard enough,” says Nico Dantuma at the Karolinska Institute in Stockholm, Sweden, who was not involved in the study.
But whether or not the drugs are likely to work in other neurodegenerative disorders involving aggregations of misfolded proteins, such as Alzheimer’s and Parkinson’s disease, is up for debate. “I don’t think their results prove that clearing misfolded proteins is not a useful therapeutic,” says Ana Maria Cuervo at Albert Einstein College of Medicine in New York. Other studies that increase the degrading of misfolded proteins have been shown to improve symptoms in other neurodegenerative diseases, she says.
"There are two sides of the coin," says Dantuma. "You might rescue functioning proteins from being degraded… but it’s too early to extrapolate these results to Alzheimer’s and Parkinson’s disease."
In the meantime, drugs that block proteasome are already used to treat cancer, so Sharma hopes they can soon be trialled in people with NCL.
Source: NewScientist
New Model Synapse Could Shed Light on Disorders Such as Epilepsy and Anxiety
A new way to study the role of a critical neurotransmitter in disorders such as epilepsy, anxiety, insomnia, depression, schizophrenia, and alcohol addiction has been developed by a group of scientists led by Gong Chen, an associate professor of biology at Penn State University.
The new method involves molecularly engineering a model synapse — a structure through which a nerve cell send signals to another cell. This model synapse can precisely control a variety of receptors for the neurotransmitter called GABA, which is important in brain chemistry. The research, which will be published in the Journal of Biological Chemistry on 10 August 2012, opens the door to the possibility of creating safer and more-efficient drugs that target GABA receptors and that cause fewer side effects.
New Generation of Virtual Humans Helping to Train Psychologists
New technology has led to the creation of virtual humans who can interact with therapists via a computer screen and realistically mimic the symptoms of a patient with clinical psychological disorders, according to new research presented at the American Psychological Association’s 120th Annual Convention.
Disorders of consciousness: How should clinicians respond to new therapeutic interventions?
August 2, 2012
New tools have confirmed high rates of misdiagnosis of patients with chronic disorders of consciousness, such as the vegetative state. An increasing number of patients’ families wish to use these novel techniques for diagnosis, prognosis, and treatment. An international team of researchers, including Dr. Éric Racine, researcher at the IRCM, analyzed the clinical, social and ethical issues that clinicians are now facing. Their article is published in the August edition of The Lancet Neurology, a renowned journal in the field of clinical neurology.
"Patients with disorders of consciousness have traditionally been regarded as unaware by definition, but findings from recent clinical studies have revealed astounding cases of awareness despite clinical unresponsiveness," explains Dr. Racine, a Montréal neuroethics specialist.
Severe brain injury can leave patients with chronic disorders of consciousness, which are medical conditions that inhibit consciousness. Patients thus have severe motor and cognitive impairments, remain fully dependent on others for all activities of daily living, and have no or very limited means to functionally communicate their thoughts or wishes, depending on their state.
Even with a careful neurological assessment of these types of disorders, some signs of awareness can elude the clinician because the clinical diagnosis relies on the observation of motor signs of awareness, which can be very subtle and fluctuate over time.
New technological developments can now measure brain function both in resting states and in response to simple commands, independent of muscle function, which could help establish a more accurate diagnosis. As a result, diagnostic classifications have been revised and prognostic knowledge is improving. For the first time, therapeutic studies have recently shown the effects of treatment on the improvement of patient responsiveness.
"The medical decision to stop or continue rehabilitation, or to transfer a patient to a long-term care facility can be hard to accept for the family, but one of the most difficult treatment decisions by family members remains whether to continue life-sustaining therapy or to discontinue it and only provide palliative care," says Dr. Racine.
Media coverage of disorders of consciousness has increased and information on the subject is increasingly available to the public. Clinicians such as neurologists, rehabilitation specialists, family doctors, and nurses must answer more requests from patients’ family members for novel diagnostic and therapeutic procedures.
"Clinicians therefore need to be prepared to discuss disorders of consciousness with ethical sensitivity, especially considering that the new procedures remain investigational," adds Dr. Racine. "They must be aware of the level of evidence supporting them and of the unavoidable ethical and social issues involved in responding to requests from patients’ family members."
Provided by Institut de recherches cliniques de Montreal
Source: medicalxpress.com