Posts tagged psychology
Articles and news from the latest research reports.
Scientists have found that eliminating an enzyme from mice with symptoms of Alzheimer’s disease leads to a 90 percent reduction in the compounds responsible for formation of the plaques linked to this form of dementia — the most dramatic reduction in this compound reported to date in published research.
After a summer marred by disappointing clinical-trial results in patients with Alzheimer’s disease, drug developers are regrouping to plot a fresh course in the battle against the devastating disorder.
The bad news began in July and August, when Johnson & Johnson and Pfizer learned that their biological drug bapineuzumab had failed to show any benefit in two large trials. Then, on 24 August, Eli Lilly said that its drug solanezumab had not hit its goal of significantly slowing the memory decline and dementia that characterize Alzheimer’s disease.
Both of the failed drugs targeted amyloid-β, a protein that forms plaques in the brains of patients with the disease and that has long been the prime suspect for causing it. But rather than abandoning the amyloid hypothesis, scientists are pinning their hopes on innovative clinical-trial designs and new diagnostics that would allow them to test compounds earlier in the disease and gauge their efficacy more quickly.
Can simply describing your feelings at stressful times make you less afraid and less anxious? A new UCLA psychology study suggests that labeling your emotions at the precise moment you are confronting what you fear can indeed have that effect.
Scientists on the Florida campus of The Scripps Research Institute have designed a compound that shows promise as a potential therapy for one of the diseases closely linked to fragile X syndrome, a genetic condition that causes mental retardation, infertility, and memory impairment, and is the only known single-gene cause of autism.
The study, published online ahead of print in the journal ACS Chemical Biology September 4, 2012, focuses on tremor ataxia syndrome, which usually affects men over the age of 50 and results in Parkinson’s like-symptoms—trembling, balance problems, muscle rigidity, as well as some neurological difficulties, including short-term memory loss and severe mood swings.
New research finds that the way that the visual centers of men and women’s brains works is different. Men have greater sensitivity to fine detail and rapidly moving stimuli, but women are better at discriminating between colors.
A Blueprint for ‘Affective’ Aggression
A North Carolina State University researcher has created a roadmap to areas of the brain associated with affective aggression in mice. This roadmap may be the first step toward finding therapies for humans suffering from affective aggression disorders that lead to impulsive violent acts.
Affective aggression differs from defensive aggression or premeditated aggression used by predators, in that the role of affective aggression isn’t clear and could be considered maladaptive. NC State neurobiologist Dr. Troy Ghashghaei was interested in finding the areas of the brain engaged with this type of aggressive behavior. Using mice that had been specially bred for affective aggression by his research associate Dr. Derrick L Nehrenberg, Ghashghaei and former undergraduate student Atif Sheikh were able to locate the regions in the mouse brain that switched on and those that were off when the mice displayed affective aggression.
“The brain works by using clusters of neurons that cross communicate at extremely rapid rates, much like a computer,” Ghashghaei explains. “One region will process a stimulus, and then that region sends messages to other clusters within the brain, like circuits within a computer. We looked at how the switches flipped in the brains of aggressive mice, and compared that with the brains of completely nonaggressive mice in the same setting, to see how the two processed the situation differently.”
They found that affectively aggressive mice demonstrated a large difference in the way their “executive centers” operated when the mice encountered another mouse. “Sensory inputs come in and are sent to the executive center, the part of the brain that decides how to respond to the input,” Ghashghaei says. “In the meantime, the information about the response you made gets processed back with either a pleasant or unpleasant association.”
According to Ghashghaei, the affectively aggressive mice could react violently because their brains are hardwiredto respond to certain situations aggressively without assessing whether their response to the situation is appropriate or without regard to the behavior’s consequences. In addition, affectively aggressive mice may be forming pleasant associations with their violent displays, which would reinforce their aggressive tendencies.
“We cannot say which of the two possibilities underlie the persistent aggressive displays by our mice,” Ghashghaei says, “but we can see that the patterns of neuronal activity are very different in the executive centers of these mice. Additionally, there are differences in the neuronal clusters involved with creating pleasant or unpleasant associations to the stimulus or their response. That gives us a few starting spots to begin identifying the mechanisms that underlie these profound behavioral differences.”
The regions of the brain that were involved in affective aggression in the mice are similar across all mammalian species. Ghashghaei hopes that his findings in mice will be useful to researchers studying violent behavior in humans, as well as aggression in other animals.
“With the brain, just knowing where to start looking is huge,” Ghashghaei says. “Once you have a few targets, you can tease out the possibilities and get to the heart of the problem. We are confident that manipulation of some of the identified targets in our study will disrupt displays of affective aggression in our mouse model.”
(Source: news.ncsu.edu)
A*STAR scientists have identified a biomarker of the most lethal form of brain tumours in adults − glioblastoma multiforme. The scientists found that by targeting this biomarker and depleting it with a potential drug, they were able to prevent the progression and relapse of the brain tumour.
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.
Reduced Brain Connections Seen in People With Generalized Anxiety Disorder
A new University of Wisconsin-Madison imaging study shows the brains of people with generalized anxiety disorder (GAD) have weaker connections between a brain structure that controls emotional response and the amygdala, which suggests the brain’s “panic button” may stay on due to lack of regulation.
Anxiety disorders are the most common class of mental disorders and GAD, which is characterized by excessive, uncontrollable worry, affects nearly 6 percent of the population.
Lead author Dr. Jack Nitschke, associate professor of psychiatry in the UW School of Medicine and Public Health, says the findings support the theory that reduced communications between parts of the brain explains the intense anxiety felt by people with GAD.
In this case, two types of scans showed the amygdala, which alerts us to threat in our surroundings and initiates the “fight-or-flight” response, seems to have weaker “white matter” connections to the prefrontal and anterior cingulate cortex (ACC), the center of emotional regulation.
The researchers did two types of imaging - diffusion tensor imaging (DTI) and functional magnetic resonance (fMRI) - on the brains of 49 GAD patients and 39 healthy volunteers. Compared with the healthy volunteers, the imaging showed the brains of people with GAD had reduced connections between the prefrontal and anterior cingulate cortex and the amygdala via the uncinate fasciculus, a primary “white matter” tract that connects these brain regions. This reduced connectivity was not found in other white matter tracts elsewhere in their brains.
"We know that in the brain, if you use a circuit you build it up, the way you build muscle by exercise,” says Nitschke, a clinical psychologist who treats patients with anxiety disorders and does research at the UW-Madison’s Waisman Center.
Nitschke says that researchers wonder if this weak connection results in the intense anticipatory anxiety and worry that is the hallmark of GAD, because the ACC is unable to tell the amygdala to “chill out.” It also suggests that behavioral therapy that teaches patients to consciously exercise this emotional regulation works to reduce anxiety by strengthening the connection.
"It’s possible that this is exactly what we’re doing when we teach patients to regulate their reactions to the negative events that come up in everyone’s lives,” Nitschke says. "We can help build people’s tolerance to uncontrollable future events by teaching them to regulate their emotions to the uncertainty that surrounds those events.
(Source: news.wisc.edu)
Stem cells bring back feeling for paralysed patients
03 September 2012 by Andy Coghlan
For the first time, people with broken spines have recovered feeling in previously paralysed areas after receiving injections of neural stem cells.
(Image: Medical Images/Getty Images)
Three people with paralysis received injections of 20 million neural stem cells directly into the injured region of their spinal cord. The cells, acquired from donated fetal brain tissue, were injected between four and eight months after the injuries happened. The patients also received a temporary course of immunosuppressive drugs to limit rejection of the cells.
None of the three felt any sensation below their nipples before the treatment. Six months after therapy, two of them had sensations of touch and heat between their chest and belly button. The third patient has not seen any change.
"The fact we’ve seen responses to light touch, heat and electrical impulses so far down in two of the patients is very unexpected," says Stephen Huhn of StemCells, the company in Newark, California, developing and testing the treatment. "They’re really close to normal in those areas now in their sensitivity," he adds.
"We are very intrigued to see that patients have gained considerable sensory function," says Armin Curt of Balgrist University Hospital in Zurich, Switzerland, where the patients were treated, and principal investigator in the trial.
The data are preliminary, but “these sensory changes suggest that the cells may be positively impacting recovery”, says Curt, who presented the results today in London at the annual meeting of the International Spinal Cord Society.