Studies Provide More Insight Into Zika Effects
Three studies reported on the effects of the Zika virus outbreak in Brazil. The first study examined CT findings of the CNS in 16 newborn babies with congenital Zika virus infection confirmed by tests in CSF. The researchers identified a pattern of CT brain findings in the babies, including decreased brain volume, simplified gyral pattern, calcifications, ventricular dilatation, and prominent occipital bone.
"We live in Pernambuco, a state in northeastern Brazil, which had the highest number of patients with microcephaly during the Zika outbreak in our country," said Natacha Calheiros de Lima Petribu, MD, of the Department of Radiology at Barão de Lucena Hospital. "Our study proves that Zika virus infection can cause congenital brain damage in babies with and without microcephaly."
Another study analyzed the imaging results of three target groups affected by Zika: adults who developed acute neurologic syndrome, newborns with vertical infection with neurologic disorders, and pregnant women with rash outbreaks suggestive of Zika. Many of the adults had symptoms of Guillain-Barré syndrome. A few showed inflammation of the brain and spinal cord (ie, Bickerstaff's encephalitis) or brainstem and spinal cord lesions. Common MRI findings included enhancement of certain spinal and facial nerves. In the newborns, MRI showed orbital injuries and anatomical changes in brain tissue.
"It was alarming to find so many cases of neurologic syndromes in adults, some very serious, related to Zika virus infection," said study author Emerson de Melo Casagrande, MD, of the Department of Radiology at Antonio Pedro University Hospital--Federal Fluminense University. "We have also noticed a difference between these syndromes, even though the trigger was the same."
In a third study, ultrasound and fetal MRI were performed on pregnant patients with Zika virus infection at different gestational ages. Once the babies were born, they underwent ultrasound, CT, and MRI. The researchers then created 3-D virtual and physical models of the skulls. More than half of the babies had microcephaly, brain calcifications, and loss of brain tissue volume, along with other structural changes.
"The emergence of Zika virus in the Americas has coincided with increased reports of babies born with microcephaly," said study author Heron Werner Jr, MD, PhD, of the Department of Radiology at Clínica de Diagnóstico por Imagem. "An early diagnosis may help in treating these babies after birth. Moreover, the knowledge of abnormalities present in the CNS may give hints about the pathophysiology of the disease."
Head Impacts Lead to Brain Changes in High School Football Players
Brain imaging exams performed on high school football players after a single season reveal changes in the gray and white matter that correlated with exposure to head impacts, according to researchers.
"It is important to understand the potential changes occurring in the brain related to youth contact sports," said Elizabeth Moody Davenport, PhD, a postdoctoral researcher at UT Southwestern Medical Center in Dallas. "We know that some professional football players suffer from a serious condition called chronic traumatic encephalopathy or CTE. We are attempting to find out when and how that process starts, so that we can keep sports a healthy activity for millions of children and adolescents."
The study included 24 players from a high school football team in North Carolina, each of whom wore a helmet outfitted with the Head Impact Telemetry System (HITS) during all practices and games. The helmets are lined with six accelerometers that measure the magnitude, location, and direction of a hit. Data from the helmets can be uploaded to a computer for analysis.
"We saw changes in these young players' brains on both structural and functional imaging after a single season of football," said Dr. Davenport.
In the study, each player underwent pre- and post-season imaging, including a specialized MRI scan, from which diffusion tensor imaging and diffusion kurtosis imaging data were extracted to measure the brain's white matter integrity, and a magnetoencephalography (MEG) scan, which records and analyzes the magnetic fields produced by brain waves. Diffusion imaging can measure the structural white matter changes in the brain, and MEG assesses changes in function.
"MEG can be used to measure delta waves in the brain, which are a type of distress signal," said Dr. Davenport. "Delta waves represent slow wave activity that increases after brain injuries. The delta waves we saw came from the surface of the brain, while diffusion imaging is a measure of the white matter deeper in the brain."
The research team calculated the change in imaging metrics between the pre- and post-season imaging exams. They measured abnormalities observed on diffusion imaging and abnormally increased delta-wave activity on MEG. The imaging results were then combined with player-specific impact data from the HITS. None of the 24 players were diagnosed with a concussion during the study.
Players with greater head impact exposure had the greatest change in diffusion imaging and MEG metrics. "Change in diffusion imaging metrics correlated most to linear acceleration, similar to the impact of a car crash," said Dr. Davenport. "MEG changes correlated most to rotational impact, similar to a boxer's punch. These results demonstrate that you need both imaging metrics to assess impact exposure, because they correlate with different biomechanical processes."
Similar studies are being conducted this fall, and a consortium has been formed to continue the brain imaging research in youth contact sports across the country, said Dr. Davenport. "Without a larger population that is closely followed in a longitudinal study, it is difficult to know the long-term effects of these changes," she said. "We do not know if the brain's developmental trajectory is altered, or if the off-season time allows for the brain to return to normal."
Depression in Soldiers Linked to Brain Disruption From Injury
Using multiple brain imaging techniques, researchers have found that a disruption of the circuitry in the brain's cognitive-emotional pathways may provide a physical foundation for depression symptoms in some service members who have had mild traumatic brain injury (mTBI) in combat. "We can link these connectivity changes in the brain to poor top-down emotional processing and greater maladaptive rumination, or worrying, in symptomatic depressed soldiers after mTBI," said Ping-Hong Yeh, PhD, scientist and physicist at the National Intrepid Center of Excellence, Walter Reed National Military Medical Center in Bethesda, Maryland.
According to the Defense and Veterans Brain Injury Center, 352,619 service members worldwide have been diagnosed with TBI since 2000, the majority of these cases being mTBI. In addition, psychiatric disorders, such as anxiety and major depressive disorders, are becoming common in military personnel with brain injuries.
"With the increased survival of soldiers due to improvements in body armor and advanced medical care, there has been an increase in the number of soldiers surviving major trauma. Consequently, a large number of soldiers are returning from war with mTBI," said Dr. Yeh. "Mood disorders are common in military-related mTBI patients. This is an ongoing problem facing a large number of warriors in current areas of conflict, and it is likely to be a persistent problem for the foreseeable future."
For the study, researchers used diffusion-weighted imaging (DWI) and resting-state functional MRI (fMRI) to examine 130 active male service members diagnosed with mTBI and a control group of 52 men without mTBI. Depression symptoms were rated based on the Beck Depression Inventory (BDI), a 21-item, self-reporting assessment that measures characteristic attitudes and symptoms of depression. Patients with a BDI score greater than 20 are considered to have moderate to severe depression symptoms.
BDI scores showed that 75 of the patients with mTBI had moderate to severe depression symptoms. Imaging results showed that white matter tracts—the circuits that connect brain regions critical for cognitive and emotional control—were disrupted in the patients with moderate to severe depression symptoms. Researchers also saw changes in the gray matter cognitive-emotional networks in these patients.
"We found consistencies in the locations of disrupted neurocircuitry, as revealed by DWI and resting-state fMRI, that are unique to the clinical symptoms of mTBI patients," said Dr. Yeh. "We have related the brain structural and functional changes in cognitive-emotional networks to depressive symptoms in mTBI patients."
This research can possibly lead to treatment strategies in the future, he added. "Though the results of this study were not applied directly to patient care, the neuroimaging changes we found might be incorporated into treatment plans for personalized medicine in the future."
Short-Term Sleep Deprivation Affects Heart Function
Getting too little sleep takes a toll on your heart, researchers reported. People who work in fire and emergency medical services, medical residencies, and other high-stress jobs are often called upon to work 24-hour shifts with little opportunity for sleep. While it is known that extreme fatigue can affect many physical, cognitive, and emotional processes, this is the first study to examine how working a 24-hour shift specifically affects cardiac function.
"For the first time, we have shown that short-term sleep deprivation in the context of 24-hour shifts can lead to a significant increase in cardiac contractility, blood pressure, and heart rate," said study author Daniel Kuetting, MD, of the Department of Diagnostic and Interventional Radiology at the University of Bonn in Germany.
For the study, Dr. Kuetting and colleagues recruited 20 healthy radiologists (19 men) with a mean age of 31.6. Each of the study participants underwent cardiovascular magnetic resonance (CMR) imaging with strain analysis before and after a 24-hour shift with an average of three hours of sleep.
"Cardiac function in the context of sleep deprivation has not previously been investigated with CMR strain analysis, the most sensitive parameter of cardiac contractility," said Dr. Kuetting. The researchers also collected blood and urine samples from the participants and measured blood pressure and heart rate.
Following short-term sleep deprivation, the participants showed significant increases in mean peak systolic strain (-23.4 vs -21.9), systolic (118.5 mmHg vs 112.8 mmHg) and diastolic (69.2 mmHg vs 62.9 mmHg) blood pressure and heart rate (68.9 bpm vs 63.0 bpm). In addition, the participants had significant increases in levels of thyroid stimulating hormone (TSH), thyroid hormones FT3 and FT4, and cortisol.
Although the researchers were able to perform follow-up examinations of half of the participants after regular sleep, further study in a larger cohort is needed to determine possible long-term effects of sleep loss, said Dr. Kuetting.
"The study was designed to investigate real-life work-related sleep deprivation," said Dr. Kuetting. "While the participants were not permitted to consume caffeine or food and beverages containing theobromine, such as chocolate, nuts, or tea, we did not take into account factors like individual stress level or environmental stimuli."
As people continue to work longer hours or work at more than one job to make ends meet, it is critical to investigate the detrimental effects of too much work and not enough sleep. The results of this pilot study are transferable to other professions in which long periods of uninterrupted labor are common, said Dr. Kuetting. "These findings may help us better understand how workload and shift duration affect public health."
Aerobic Exercise Preserves Brain Volume and Improves Cognitive Function
Using a new MRI technique, researchers have found that adults with mild cognitive impairment (MCI) who exercised four times per week during a six-month period experienced an increase in brain volume in specific areas of the brain, but adults who participated in aerobic exercise experienced greater gains than those who just stretched.
"Even over a short period of time, we saw aerobic exercise lead to a remarkable change in the brain," said Laura D. Baker, PhD, Associate Professor of Gerontology and Geriatric Medicine at Wake Forest School of Medicine (WFSM) in Winston-Salem, North Carolina.
The study included 35 adults with MCI participating in a randomized, controlled trial of exercise intervention. The participants were separated into two groups. Sixteen adults (average age, 63) engaged in aerobic activity, including treadmill, stationary bike, or elliptical training, four times per week for six months. A control group of 19 adults (average age, 67) participated in stretching exercises with the same frequency. High-resolution brain MR images were acquired from all participants before and after the six-month activity period. The MRI results were compared using conventional and biomechanical metrics to measure the change in brain volume and shape.
"We used high-resolution MR images to measure anatomical changes within areas of the brain to obtain volumetric data and directional information," said Jeongchul Kim, PhD, a coinvestigator at WFSM.
The analysis revealed that for both the aerobic and stretching groups, brain volume increased in most gray matter regions, including the temporal lobe, which supports short-term memory.
"Compared to the stretching group, the aerobic activity group had greater preservation of total brain volume, increased local gray matter volume, and increased directional stretch of brain tissue," said Dr. Kim.
Among participants of the stretching group, the analysis revealed a local contraction, or atrophy, within the white matter connecting fibers. Such directional deformation, or shape change, is partially related to volume loss, but not always, according to Dr. Kim.
"Directional changes in the brain without local volume changes could be a novel biomarker for neurologic disease," he said. "It may be a more sensitive marker for the tiny changes that occur in a specific brain region before volumetric changes are detectable on MRI."
Both MRI measures are important to the treatment of MCI and Alzheimer's disease, which require the careful tracking of changes in the brain while patients engage in interventions, including diet and exercise, to slow the progression of the disease.
Study participants were tested to determine the effect of exercise intervention on cognitive performance. Participants in the aerobic exercise group showed statistically significant improvement in executive function after six months, whereas the stretching group did not improve.
"Any type of exercise can be beneficial," said Dr. Kim. "If possible, aerobic activity may create potential benefits for higher cognitive functioning."