Posts tagged brain injury

Posts tagged brain injury

New Research on the Effects of Traumatic Brain Injury (TBI)
Considerable opportunity exists to improve interventions and outcomes of traumatic brain injury (TBI) in older adults, according to three studies published in the recent online issue of NeuroRehabilitation by researchers from the Icahn School of Medicine at Mount Sinai.
An Exploration of Clinical Dementia Phenotypes Among Individuals With and Without Traumatic Brain Injury
Some evidence suggests that a history of TBI is associated with an increased risk of dementia later in life, but the clinical features of dementia associated with TBI have not been well investigated. Researchers at the Icahn School of Medicine as well as other institutions analyzed data from elderly individuals with dementia with and without a history of TBI to characterize the clinical profiles of patients with post-TBI dementia.
The results of the study indicate that compared to older adults with dementia with no history of TBI, those with a history of TBI had higher fluency and verbal memory scores and later onset of decline. However, their general health was worse, they were more likely to have received medical attention for depression, and were more likely to have a gait disorder, falls, and motor slowness. These findings suggest that dementia among individuals with a history of TBI may represent a unique clinical phenotype that is distinct from that seen among elderly individuals who develop dementia without a history of TBI.
"Our study indicates that individuals with dementia and without a history of TBI may present clinical characteristics that differ in subtle but meaningful ways," said Kristen Dams-O’Connor, PhD, first author of the study and an Assistant Professor of Rehabilitation Medicine at the Icahn School of Medicine at Mount Sinai. "It is imperative that clinicians take a history of TBI into account when making dementia diagnoses."
For this study, researchers used data from the National Alzheimer’s Coordinating Center (NACC) Uniform Data Set (UDS) collected between September 2005 and May 2012 to analyze 332 elderly individuals with dementia and a history of TBI and 664 elderly individuals without dementia who do have a history of TBI. Statistical analyses focused on evaluating differences in the areas of neurocognitive functioning, psychiatric functioning, medical history and health, clinical characteristics of dementia, and dementia diagnosis using data collected at the baseline (first) NACC study visit.
Mortality of Elderly Individuals with TBI in the First 5 Years Following Injury
After observing a high rate of mortality among patients over the age of 55 in the first five years after sustaining a TBI, researchers at the Icahn School of Medicine at Mount Sinai were interested in learning more about the precise causes for what may be considered a premature death.
The results of this study indicate that for approximately a third of the patients, death one to five years after TBI resulted from health conditions that were present at the time of injury before the onset of TBI, suggesting a continuation of an already ongoing process. The remainder of patients died from conditions that appeared to unfold in the years after injury. According to the authors, each cause of death in this sample would have required pro-active medical management, medical intervention and medication compliance.
"Like those with other chronic health conditions, individuals with TBI could benefit from the development of a disease management model of primary care," said one of the study authors, Wayne Gordon, PhD, Jack Nash Professor and Vice Chair of the Department of Rehabilitation Medicine at the Icahn School of Medicine at Mount Sinai and Chief of the Rehabilitation Psychology and Neuropsychology service. "This study suggests that close medical management and lifestyle interventions may help to prevent premature death among elderly survivors of TBI in the future."
Researchers reviewed the charts of 30 individuals over the age of 55 who completed inpatient acute rehabilitation during the period from 2003-2009 and who died one to four years after TBI, and then compared that data to a matched sample of 30 patients who did not die. They found that 53 percent of deceased subjects had been diagnosed with gait abnormalities, 32 percent were taking respiratory medications at admission, and 17 percent were taking respiratory medications at discharge. Compared to patients who survived several years after injury, deceased patients were discharged from the hospital with significantly more medications.
Inpatient Rehabilitation for Traumatic Brain Injury: The Influence of Age on Treatments and Outcomes
For this study, researchers analyzed the difference in treatment and outcomes between elderly and younger patients with TBI. They found that patients over 65 had lower brain injury severity and a shorter length of stay in acute care. Elderly patients also received fewer hours of rehabilitation therapy, due to a shorter length of stay, and fewer hours of treatment per day, especially from psychology and therapeutic recreation. They gained less functional ability during and after rehabilitation, and had a very high mortality rate.
"We know significantly more about the treatment received by adolescents and young adults with TBI than we do about those over 65," said Marcel Dijkers, PhD, lead author and Research Professor in the Department of Rehabilitation Medicine at Mount Sinai. "Our data indicates that elderly people can be rehabilitated successfully, but it raises a number of questions. For instance: is the high mortality due to the TBI or is it the result of the continuation of a condition that began pre-TBI?"
The researchers analyzed data on 1,419 patients with TBI admitted to nine TBI rehabilitation inpatient programs across the country between 2009 and 2011. They collected data through abstracting of medical records, point-of-care forms completed by therapists, and interviews conducted three and nine months after discharge.
Researchers scoring a win-win with novel set of concussion diagnostic tools
From Junior Seau, former San Diego Chargers linebacker, to Dave Duerson, former Chicago Bears safety — who both committed suicide as a result of chronic traumatic encephalopathy (CTE) — traumatic brain injuries (TBIs) have been making disturbing headlines at an alarming rate. In the United States alone, TBIs account for an estimated 1.6 million to 3.8 million sports injuries every year, with approximately 300,000 of those being diagnosed among young, nonprofessional athletes. But TBIs are not confined to sports; they are also considered a signature wound among soldiers of the Iraq and Afghanistan wars.
The potential impact on the health and well-being of individuals with brain injuries are numerous. These individuals might display a range of symptoms — such as headaches, depression, loss of memory and loss of brain function — that may persist for weeks or months. The effects of brain injuries are most devastating when they remain unrecognized for long periods of time. This is where Christian Poellabauer, associate professor of computer science and engineering; Patrick Flynn, professor of computer science and engineering; Nikhil Yadav, graduate student of computer science and engineering; and a team of students and faculty are making their own impact.
Although baseline tests of athletes prior to an injury are trending up, these tests must still be compared to examinations after an injury has occurred. They require heavy medical equipment, such as a CT scanner, MRI equipment or X-ray machine, and are not always conclusive. The Notre Dame team has developed a tablet-based testing system that captures the voice of an individual and analyzes the speech for signs of a potential concussion anytime, anywhere, in real time.
“This project is a great example of how mobile computing and sensing technologies can transform health care,” Poellabauer said. “More important, because almost 90 percent of concussions go unrecognized, this technology offers tremendous potential to reduce the impact of concussive and subconcussive hits to the head.”
The system sounds simple enough: An individual speaks into a tablet equipped with the Notre Dame program before and after an event. The two samples are then compared for TBI indicators, which include distorted vowels, hyper nasality and imprecise consonants.
Notre Dame’s system offers a variety of advantages over traditional testing, such as portability, high accuracy, low cost and a low probability of manipulation (the results cannot be faked); it has also proven very successful. In testing that occurred during the Notre Dame Bengal Bouts and Baraka Bouts, annual student boxing tournaments, the researchers established baselines for boxers using tests such as the Axon Sports Computerized Cognitive Assessment Tool (CCAT), the Sport Concussion Assessment Tool 2 (SCAT2) and the Notre Dame iPad-based reading and voice recording test.
During the 2012 Bengal Bouts, nine concussions (out of 125 participants) were confirmed by this new speech-based test and the University’s medical team. Separate tests of 80 female boxers were also conducted during the 2012 Baraka Bouts. Outcomes of the 2013 Bengal Bouts are currently being compared to the findings of the University medical team on approximately 130 male boxers.
The testing was done in cooperation with James Moriarity, the University’s chief sports medicine physician, who has developed a series of innovative concussion testing studies.

With more than one million athletes now experiencing a concussion each year in the United States, the American Academy of Neurology (AAN) has released an evidence-based guideline for evaluating and managing athletes with concussion. This new guideline replaces the 1997 AAN guideline on the same topic. The new guideline is published in the March 18, 2013, online issue of Neurology®, the medical journal of the American Academy of Neurology, was developed through an objective evidence-based review of the literature by a multidisciplinary committee of experts and has been endorsed by a broad range of athletic, medical and patient groups.
“Among the most important recommendations the Academy is making is that any athlete suspected of experiencing a concussion immediately be removed from play,” said co-lead guideline author Christopher C. Giza, MD, with the David Geffen School of Medicine and Mattel Children’s Hospital at UCLA and a member of the AAN. “We’ve moved away from the concussion grading systems we first established in 1997 and are now recommending concussion and return to play be assessed in each athlete individually. There is no set timeline for safe return to play.”
The updated guideline recommends athletes with suspected concussion be immediately taken out of the game and not returned until assessed by a licensed health care professional trained in concussion, return to play slowly and only after all acute symptoms are gone. Athletes of high school age and younger with a concussion should be managed more conservatively in regard to return to play, as evidence shows that they take longer to recover than college athletes.
The guideline was developed reviewing all available evidence published through June 2012. These practice recommendations are based on an evaluation of the best available research. In recognition that scientific study and clinical care for sports concussions involves multiple specialties, a broad range of expertise was incorporated in the author panel. To develop this document, the authors spent thousands of work hours locating and analyzing scientific studies. The authors excluded studies that did not provide enough evidence to make recommendations, such as reports on individual patients or expert opinion. At least two authors independently analyzed and graded each study.
According to the guideline:
Signs and symptoms of a concussion include:
Headache and sensitivity to light and sound Changes to reaction time, balance and coordination Changes in memory, judgment, speech and sleep Loss of consciousness or a “blackout” (happens in less than 10 percent of cases)
“If in doubt, sit it out,” said Jeffrey S. Kutcher, MD, with the University of Michigan Medical School in Ann Arbor and a member of the AAN. “Being seen by a trained professional is extremely important after a concussion. If headaches or other symptoms return with the start of exercise, stop the activity and consult a doctor. You only get one brain; treat it well.”
The guideline states that while an athlete should immediately be removed from play following a concussion, there is currently insufficient evidence to support absolute rest after concussion. Activities that do not worsen symptoms and do not pose a risk of repeat concussion may be part of concussion management.
The guideline is endorsed by the National Football League Players Association, the American Football Coaches Association, the Child Neurology Society, the National Association of Emergency Medical Service Physicians, the National Academy of Neuropsychology, the National Association of School Psychologists, the National Athletic Trainers Association and the Neurocritical Care Society.

New Early Warning System for the Brain Development of Babies
A new research technique, pioneered by Dr. Maria Angela Franceschini, was published in JoVE (Journal of Visualized Experiments) on March 14th. Researchers at Massachusetts General Hospital and Harvard Medical School have developed a non-invasive optical measurement system to monitor neonatal brain activity via cerebral metabolism and blood flow.
Of the nearly four million children born in the United States each year, 12% are born preterm, 8% are born with low birth weight, and 1-2% of infants are at risk for death associated with respiratory distress. The result is an average infant mortality rate of 6 deaths per 1,000 live births. These statistics, though low compared to those of 50 or even 20 years ago, are troubling both to parents and to clinicians. Until recently there were no effective bedside methods to screen for brain injury or monitor injury progression that can contribute to developmental abnormalities or infant mortality. Dr. Franceschini’s new system does both.
“We want to measure cerebral vascular development and brain health in babies,” Dr. Franceschini tells us. Because neuronal metabolism is hard to measure directly, scientists instead evaluate cerebral oxygen metabolism, which highly corresponds to neuronal metabolism. Dr. Franceschini and her team have developed a near infrared optical system to quantify cerebral oxygen metabolism by measuring blood oxygen saturation and blood flow.
The technology is an improvement on continuous-wave near-infrared spectroscopy (CWNIRS), which measures oxygen saturation but does not provide long-term or real time brain monitoring. Instead, frequency-domain near-infrared spectroscopy (FDNIRS) is used in conjunction with diffuse correlation spectroscopy (DCS) to get a more robust evaluation of infant health. Dr. Franceschini explains, “CWNIRS has been used for many years but it only provides relative measurements of blood oxygen saturation. Our technology allows quantification of multiple vascular parameters and evaluation of oxygen metabolism which gives a more direct picture of infant distress.”
“This technology will let us monitor babies who may be having seizures, cerebral hemorrhages, or other cerebral distresses and may allow us to expedite treatment,” says Dr. Franceschini, who plans to develop and streamline this technology to one that nurses can use clinically. “We chose to publish in JoVE because it is important to show how these measurements can be done and this publication lets us reach early adopters.”
Single Concussion May Cause Lasting Brain Damage
A single concussion may cause lasting structural damage to the brain, according to a new study published online in the journal Radiology.
"This is the first study that shows brain areas undergo measureable volume loss after concussion," said Yvonne W. Lui, M.D., Neuroradiology section chief and assistant professor of radiology at NYU Langone School of Medicine. "In some patients, there are structural changes to the brain after a single concussive episode."
According to the Centers for Disease Control and Prevention, each year in the U.S., 1.7 million people sustain traumatic brain injuries, resulting from sudden trauma to the brain. Mild traumatic brain injury (MTBI), or concussion, accounts for at least 75 percent of all traumatic brain injuries.
Following a concussion, some patients experience a brief loss of consciousness. Other symptoms include headache, dizziness, memory loss, attention deficit, depression and anxiety. Some of these conditions may persist for months or even years.
Studies show that 10 to 20 percent of MTBI patients continue to experience neurological and psychological symptoms more than one year following trauma. Brain atrophy has long been known to occur after moderate and severe head trauma, but less is known about the lasting effects of a single concussion.
Dr. Lui and colleagues set out to investigate changes in global and regional brain volume in patients one year after MTBI. Twenty-eight MTBI patients (with 19 followed at one year) with post-traumatic symptoms after injury and 22 matched controls (with 12 followed at one year) were enrolled in the study. The researchers used three-dimensional magnetic resonance imaging (MRI) to determine regional gray matter and white matter volumes and correlated these findings with other clinical and cognitive measurements.
The researchers found that at one year after concussion, there was measurable global and regional brain atrophy in the MTBI patients. These findings show that brain atrophy is not exclusive to more severe brain injuries but can occur after a single concussion.
"This study confirms what we have long suspected," Dr. Lui said. "After MTBI, there is true structural injury to the brain, even though we don’t see much on routine clinical imaging. This means that patients who are symptomatic in the long-term after a concussion may have a biologic underpinning of their symptoms."
Certain brain regions showed a significant decrease in regional volume in patients with MTBI over the first year after injury, compared to controls. These volume changes correlated with cognitive changes in memory, attention and anxiety.
"Two of the brain regions affected were the anterior cingulate and the precuneal region," Dr. Lui said. "The anterior cingulate has been implicated in mood disorders including depression, and the precuneal region has a lot of different connections to areas of the brain responsible for executive function or higher order thinking."
According to Dr. Lui, researchers are still investigating the long-term effects of concussion, and she advises caution in generalizing the results of this study to any particular individual.
"It is important for patients who have had a concussion to be evaluated by a physician," she said. "If patients continue to have symptoms after concussion, they should follow-up with their physician before engaging in high-risk activities such as contact sports."
Even mild traumatic brain injuries can kill brain tissue
Scientists have watched a mild traumatic brain injury play out in the living brain, prompting swelling that reduces blood flow and connections between neurons to die.
“Even with a mild trauma, we found we still have these ischemic blood vessels and, if blood flow is not returned to normal, synapses start to die,” said Dr. Sergei Kirov, neuroscientist and Director of the Human Brain Lab at the Medical College of Georgia at Georgia Regents University.
They also found that subsequent waves of depolarization – when brain cells lose their normal positive and negative charge – quickly and dramatically increase the losses.
Researchers hope the increased understanding of this secondary damage in the hours following an injury will point toward better therapy for the 1.7 million Americans annually experiencing traumatic brain injuries from falls, automobile accidents, sports, combat and the like. While strategies can minimize impact, no true neuroprotective drugs exist, likely because of inadequate understanding about how damage unfolds after the immediate impact.
Kirov is corresponding author of a study in the journal Brain describing the use of two-photon laser scanning microscopy to provide real-time viewing of submicroscopic neurons, their branches and more at the time of impact and in the following hours.
Scientists watched as astrocytes – smaller cells that supply neurons with nutrients and help maintain normal electrical activity and blood flow – in the vicinity of the injury swelled quickly and significantly. Each neuron is surrounded by several astrocytes that ballooned up about 25 percent, smothering the neurons and connective branches they once supported.
“We saw every branch, every small wire and how it gets cut,” Kirov said. “We saw how it destroys networks. It really goes downhill. It’s the first time we know of that someone has watched this type of minor injury play out over the course of 24 hours.”
Stressed neurons ran out of energy and became silent but could still survive for hours, potentially giving physicians time to intervene, unless depolarization follows. Without sufficient oxygen and energy, internal pumps that ensure proper polarity by removing sodium and pulling potassium into neurons, can stop working and dramatically accelerate brain-cell death.
“Like the plus and minus ends of a battery, neurons must have a negative charge inside and a positive charge outside to fire,” Kirov said. Firing enables communication, including the release of chemical messengers called neurotransmitters.
“If you have six hours to save tissue when you have just lost part of your blood flow, with this spreading depolarization, you lose tissue within minutes,” he said.
While common in head trauma, spreading depolarization would not typically occur in less-traumatic injuries, like his model. His model was chemically induced to reveal more about how this collateral damage occurs and whether neurons could still be saved. Interestingly, researchers found that without the initial injury, brain cells completely recovered after re-polarization but only partially recovered in the injury model.
While very brief episodes of depolarization occur as part of the healthy firing of neurons, spreading depolarization exacerbates the initial traumatic brain injury in more than half of patients and results in poor prognosis, previous research has shown. However, a 2011 review in the journal Nature Medicine indicated that short-lived waves can actually protect surrounding brain tissue. Kirov and his colleagues wrote that more study is needed to determine when to intervene.
One of Kirov’s many next steps is exploring the controversy about whether astrocytes’ swelling in response to physical trauma is a protective response or puts the cells in destruct mode. He also wants to explore better ways to protect the brain from the growing damage that can follow even a slight head injury.
Currently, drugs such as diuretics and anti-seizure medication may be used to help reduce secondary damage of traumatic brain injury. Astrocytes can survive without neurons but the opposite is not true, Kirov said. The ratio of astrocytes to neurons is higher in humans and human astrocytes are more complex, Kirov said.

Cooling may prevent trauma-induced epilepsy
In the weeks, months and years after a severe head injury, patients often experience epileptic seizures that are difficult to control. A new study in rats suggests that gently cooling the brain after injury may prevent these seizures.
“Traumatic head injury is the leading cause of acquired epilepsy in young adults, and in many cases the seizures can’t be controlled with medication,” says senior author Matthew Smyth, MD, associate professor of neurological surgery and of pediatrics at Washington University School of Medicine in St. Louis. “If we can confirm cooling’s effectiveness in human trials, this approach may give us a safe and relatively simple way to prevent epilepsy in these patients.”
The researchers reported their findings in Annals of Neurology.
Cooling the brain to protect it from injury is not a new concept. Cooling slows down the metabolic activity of nerve cells, and scientists think this may make it easier for brain cells to survive the stresses of an injury.
Doctors currently cool infants whose brains may have had inadequate access to blood or oxygen during birth. They also cool some heart attack patients to reduce peripheral brain damage when the heart stops beating.
Smyth has been exploring the possibility of using cooling to prevent seizures or reduce their severity.
“Warmer brain cells seem to be more electrically active, and that may increase the likelihood of abnormal electrical discharges that can coalesce to form a seizure,” Smyth says. “Cooling should have the opposite effect.”
Smyth and colleagues at the University of Washington and the University of Minnesota test potential therapies in a rat model of brain injury. These rats develop chronic seizures weeks after the injury.
Researchers devised a headset that cools the rat brain. They were originally testing its ability to stop seizures when they noticed that cooling seemed to be not only stopping but also preventing seizures.
Scientists redesigned the study to focus on prevention. Under the new protocols, they put headsets on some of the rats that cooled their brains by less than 4 degrees Fahrenheit. Another group of rats wore headsets that did nothing. Scientists who were unaware of which rats they were observing monitored them for seizures during treatment and after the headsets were removed.
Rats that wore the inactive headset had progressively longer and more severe seizures weeks after the injury, but rats whose brains had been cooled only experienced a few very brief seizures as long as four months after injury.
Brain injury also tends to reduce cell activity at the site of the trauma, but the cooling headsets restored the normal activity levels of these cells.
The study is the first to reduce injury-related seizures without drugs, according to Smyth, who is director of the Pediatric Epilepsy Surgery program at St. Louis Children’s Hospital.
“Our results show that the brain changes that cause this type of epilepsy happen in the days and weeks after injury, not at the moment of injury or when the symptoms of epilepsy begin,” says Smyth. “If clinical trials confirm that cooling has similar effects in humans, it could change the way we treat patients with head injuries, and for the first time reduce the chance of developing epilepsy after brain injury.”
Smyth and his colleagues have been testing cooling devices in humans in the operating room, and are planning a multi-institutional trial of an implanted focal brain cooling device to evaluate the efficacy of cooling on established seizures.
When Brain Damage Unlocks The Genius Within
Brain damage has unleashed extraordinary talents in a small group of otherwise ordinary individuals. Will science find a way for everyone to tap their inner virtuoso?
A new type of prophylactic treatment for brain injury following prolonged epileptic seizures has been developed by Emory University School of Medicine investigators.
Status epilepticus, a persistent seizure lasting longer than 30 minutes [check this, some people say FIVE], is potentially life-threatening and leads to around 55,000 deaths each year in the United States. It can be caused by stroke, brain tumor or infection as well as inadequate control of epilepsy. Physicians or paramedics now treat status epilepticus by administering an anticonvulsant or general anesthesia, which stops the seizures.
Researchers at Emory have been looking for something different: anti-inflammatory compounds that can be administered after acute status epilepticus has ended to reduce damage to the brain. They have discovered a potential lead compound that can reduce mortality when given to mice after drug-induced seizures.
The results are scheduled for publication Monday in Proceedings of the National Academy of Sciences Early Edition.
"For adults who experience a period of status epilepticus longer than one hour, more than 30 percent die within four weeks of the event, making this a major medical problem," says Ray Dingledine, PhD, chair of the Department of Pharmacology at Emory University School of Medicine. "Medications that would reduce the severe consequences of refractory status epilepticus have been elusive. We believe we have an effective route to minimizing the brain injury caused by uncontrolled status epilepticus."
Dingledine’s laboratory has identified compounds that block the effects of prostaglandin E2, a hormone involved in processes such as fever, childbirth, digestion and blood pressure regulation. Prostaglandin E2 is also involved in the toxic inflammation in the brain arising after status epilepticus.
The first author of the paper is postdoctoral fellow Jianxiong Jiang, PhD, and the medicinal chemist largely responsible for developing the compounds is Thota Ganesh, PhD.
Jiang and colleagues induced status epilepticus in mice with the alkaloid drug pilocarpine, and gave them a compound, TG6-10-1, starting four hours later and again at 21 and 30 hours. TG6-10-1 blocks signals from EP2, one of four receptors for prostaglandin E2.
Among animals that received the EP2 blocker, 90 percent survived after one week, while 60 percent of a control group survived. The scientists also used nest-building behavior and weight loss as gauges of damage to the brain. Four days after status epilepticus, all the animals that received TG6-10-1 displayed normal nest-building, but more than a quarter of living control animals were not able to build nests. In addition, the brains of TG6-10-1-treated mice had reduced levels of inflammatory messenger proteins called cytokines, less brain injury and less breach of the blood-brain-barrier.
Consequences of refractory status epilepticus can include brain damage, difficulty breathing, abnormal heart rhythms and heart failure.
Dingledine says the first clinical test of an EP2 blocking compound would probably be as an add-on treatment for prolonged status epilepticus, several hours after seizures have ended. It could also be tested in similar situations such as subarachnoid hemorrhage, prolonged febrile seizures or medication-resistant epilepsy, he says.
Dingledine and his colleagues have a patent pending for novel technology related to this research. Under Emory policies, they are eligible to receive a portion of any royalties or fees received by Emory from this technology.
(Source: eurekalert.org)
Vascular brain injury from conditions such as high blood pressure and stroke are greater risk factors for cognitive impairment among non-demented older people than is the deposition of the amyloid plaques in the brain that long have been implicated in conditions such as Alzheimer’s disease, a study by researchers at the Alzheimer’s Disease Research Center at UC Davis has found.
Published online early today in JAMA Neurology (formerly Archives of Neurology), the study found that vascular brain injury had by far the greatest influence across a range of cognitive domains, including higher-level thinking and the forgetfulness of mild cognitive decline.
The researchers also sought to determine whether there was a correlation between vascular brain injury and the deposition of beta amyloid (Αβ) plaques, thought to be an early and important marker of Alzheimer’s disease, said Bruce Reed, associate director of the UC Davis Alzheimer’s Disease Research Center in Martinez, Calif. They also sought to decipher what effect each has on memory and executive functioning.
“We looked at two questions,” said Reed, professor in the Department of Neurology at UC Davis. “The first question was whether those two pathologies correlate to each other, and the simple answer is ‘no.’ Earlier research, conducted in animals, has suggested that having a stroke causes more beta amyloid deposition in the brain. If that were the case, people who had more vascular brain injury should have higher levels of beta amyloid. We found no evidence to support that.”
"The second,” Reed continued, “was whether higher levels of cerebrovascular disease or amyloid plaques have a greater impact on cognitive function in older, non-demented adults. Half of the study participants had abnormal levels of beta amyloid and half vascular brain injury, or infarcts. It was really very clear that the amyloid had very little effect, but the vascular brain injury had distinctly negative effects.”
“The more vascular brain injury the participants had, the worse their memory and the worse their executive function – their ability to organize and problem solve,” Reed said.
The research was conducted in 61 male and female study participants who ranged in age from 65 to 90 years old, with an average age of 78. Thirty of the participants were clinically “normal,” 24 were cognitively impaired and seven were diagnosed with dementia, based on cognitive testing. The participants had been recruited from Northern California between 2007 to 2012.
The study participants underwent magnetic resonance imaging (MRI) ― to measure vascular brain injury ― and positron emission tomography (PET) scans to measure beta amyloid deposition: markers of the two most common pathologies that affect the aging brain. Vascular brain injury appears as brain infarcts and “white matter hyperintensities” in MRI scans, areas of the brain that appear bright white.
The study found that both memory and executive function correlated negatively with brain infarcts, especially infarcts in cortical and sub-cortical gray matter. Although infarcts were common in this group, the infarcts varied greatly in size and location, and many had been clinically silent. The level of amyloid in the brain did not correlate with either changes in memory or executive function, and there was no evidence that amyloid interacted with infarcts to impair thinking.
Reed said the study is important because there’s an enormous amount of interest in detecting Alzheimer’s disease at its earliest point, before an individual exhibits clinical symptoms. It’s possible to conduct a brain scan and detect beta amyloid in the brain, and that is a very new development, he said.
“The use of this diagnostic tool will become reasonably widely available within the next couple of years, so doctors will be able to detect whether an older person has abnormal levels of beta amyloid in the brain. So it’s very important to understand the meaning of a finding of beta amyloid deposition,” Reed said.
“What this study says is that doctors should think about this in a little more complicated way. They should not forget about cerebrovascular disease, which is also very common in this age group and could also cause cognitive problems. Even if a person has amyloid plaques, those plaques may not be the cause of their mild cognitive symptoms.”
(Source: ucdmc.ucdavis.edu)