Walking reduces Alzheimer's progression, 1.5-tesla MRI shows

With the help of 1.5-tesla MRI, researchers at the University of Pittsburgh have found that walking 5 miles per week helps reduce the progression of mild cognitive impairment and Alzheimer's disease in adults already afflicted with the condition, according to a study presented today at the RSNA annual meeting.

The findings expand upon results of a previous study released last month, which found that walking at least 6 miles per week helped to preserve brain size and prevent the onset of dementia in healthy adults.
"Physical activity boosts the brain's resistance to Alzheimer's," said lead study author Cyrus Raji, PhD, from the university's department of radiology. "People who walked more had a slower progression of Alzheimer's disease and mild cognitive impairment over five years, and, as a result, they had a better preservation of the hippocampus, the frontal lobes, and the temporal lobes."
Patients were recruited from the Cardiovascular Health Study - Cognition Study (CHS-CS), which began approximately 20 years ago to explore coronary heart disease and stroke in people ages 65 and older.



Physical activity



Raji and colleagues analyzed the relationship between physical activity and brain structure in 426 people, including 299 healthy adults (mean age, 78 years) and 127 cognitively impaired adults (mean age, 81 years). Among the 127 cognitively impaired adults, 83 people had mild cognitive impairment and 44 adults had Alzheimer's dementia.
"Mild cognitive impairment is believed to be a very early presentation of dementia with symptoms that are not as advanced as Alzheimer's," Raji said. "As many as 50% of the people who have mild cognitive impairment go on to develop Alzheimer's."
In addition to the MRI scans, patients were given the mini-mental state exam (MMSE) to track cognitive decline over five years. Physical activity levels were correlated with MRI and MMSE results. The analysis adjusted for age, gender, body fat composition, head size, education, and other factors.
Among those who began the study as normal and eventually developed Alzheimer's and mild cognitive impairment over 10 years, the people who walked 5 miles per week -- a little less than 1 mile per day -- had similar preservation of brain volume compared to people who remained healthy longer.

image1

Alzheimer's progression

"What excites me the most is that individuals who walked 5 miles per week and developed mild cognitive impairment and Alzheimer's disease did not lose as much brain tissue over time," Raji said. "So the people who walked more had a slower progression of Alzheimer's disease and mild cognitive impairment and, as a result, they had a better preservation of the hippocampus, the frontal lobes, and the temporal lobes."
Another significant finding came from the longitudinal MMSE test results. "In the people who developed Alzheimer's disease and walked 5 miles per week, their MMSE scores went down only one point over 10 years," Raji said. "With sedentary individuals who developed Alzheimer's, their scores went down five points over 10 years."
These findings persisted even after adjusting for factors such as age, gender, race, education, and stroke. The researchers directly attributed the improvement in memory loss to the preserved hippocampal volume from walking.


image2

Raji and his colleagues plan to continue their research of what factors contribute to Alzheimer's and mild cognitive impairment by looking at diet.

"A lot of research is being done to determine if fish oil, for example, can have a beneficial effect in preventing Alzheimer's disease or reducing the risk," he said. "There have been studies done in the past suggesting that fish oil, which helps make up the building blocks of cell membranes and helps with cholesterol metabolism, might have other beneficial effects on the brain as well."

By Wayne Forrest

image 1 :The images compare the beneficial effects of physical activity on the brains of 299 healthy aging individuals to the positive relationships between exercise and brain structure in 127 people with either mild cognitive impairment or Alzheimer's. In both normal aging and cognitive impairment, physical activity preserves volume in brain areas that are important for memory, learning, and attention. These structures include the prefrontal cortex and temporal cortex. The top row of images shows these relationships in a 3D rendering of the brain, while the bottom row shows the prefrontal cortex findings in side view cutaway images of the brain.

image 2 :Side-view cutaway images show the sparing of brain volume in 299 healthy aging people (left) and 127 individuals with cognitive impairment and Alzheimer's (right). In both groups, there is more frontal lobe volume with walking about 1 mile per day, which translates to a reduced risk for cognitive impairment in the healthy aging group and slower decline in the cognitively impaired group.

Brain MRI recommended for children with hydrocephalus

CT imaging, the most commonly used neuroimaging procedure to monitor children with shunted hydrocephalus, also puts these patients at high risk of developing a radiation-related fatal cancer as adults. MRI exams using rapid brain protocols can produce diagnostically acceptable results and eliminate the risk from repeated exposure to CT radiation dose.

In addition to not subjecting children -- especially very young children -- to radiation dose exposure, rapid MRI of the brain has been proved satisfactory for assessing ventricular size, and it does not require sedation because image acquisition can be completed in 20 seconds.
Pediatric radiologists from Children's Medical Center in Dallas made this MRI recommendation to RSNA attendees earlier this week, while delivering a sobering assessment of the cancer risk they believe their patients would face if head CT exams were continued until the children reached 20 years of age.
In a discussion of the risks of CT, it was acknowledged that the lifetime cancer risk of having a head CT scan is considerably less than with other types of CT exams, especially when low-dose protocols are utilized. Korgun Koral, MD, an associate professor of pediatric radiology at the University of Texas Southwestern Medical Center in Dallas, addressed the subject.
A 3-year-old girl has an eight in 10,000 mean lifetime risk of developing a radiation-related cancer from a head CT exam, compared to 40 in 10,000 odds with a chest CT exam. Also, the older the patient, the less the radiation dose risk. The risk of radiation-related cancer from a head CT exam is halved for a 15-year-old girl, and is halved again at age 30. (For boys, the risk is nine in 10,000, five in 10,000, and three in 10,000 at ages 3, 15, and 30, respectively.)
However, comparative assessments do not diminish the risks to a pediatric patient with shunted hydrocephalus. These patients typically have head CT exams several times a year, usually beginning at very young ages. Hydrocephalus, affects one in every 500 children, according to the National Institute of Neurological Disorders and Stroke (NINDS) in Bethesda, MD.
To treat the condition, which may be congenital or acquired, shunt systems are used to drain the cerebrospinal fluid. Treatment improvements have increased the life expectancy of these patients, Koral said.
Koral and colleagues conducted a retrospective study to estimate the lifetime attributable risk of children with shunted hydrocephalus developing a fatal cancer due to head CT for ventricular size assessment. They reviewed the medical records of Children's Medical Center from January 2009 through March 2010.
The researchers identified 150 patients, 81 of whom were female. The average age of the patients was 1.76 years, although ages ranged from 1 day to almost 19 years. To calculate the average number of exams per year that each patient underwent, the researchers counted neuroimaging studies residing in the hospital's PACS archive that were performed on these patients. In total, 211 rapid brain MRI exams and 910 head CT exams were identified. They found that 85% percent of the CT exams were performed between 6:00 a.m. and 9:00 p.m., when MRI technologists were on duty at the hospital and MRI exams could have been scheduled instead.
On average, four neuroimaging studies were performed each year, and the researchers made the assumption that these studies began for a typical patient in the second year of life. The lifetime attributable risk of developing a fatal cancer was calculated with the assumption that a patient would have four exams per year through the age of 20.
"At our hospital, the low-dose CT protocol used for hydrocephalus evaluation is 1.1 mSv, and if a standard CT protocol is used, 2.5 mSv," Koral said. "If a low dose is used consistently throughout an 18-year period, the risk of developing a fatal cancer is one in 124. If the standard dose is utilized, the risk is one in 52 patients."
"What this means is that in our current patient population, between one and three children will develop a fatal cancer if they survive to live an average adult lifetime," he said.
The researchers determined these risk estimates based on the Biologic Effects of Ionizing Radiation (BEIR) VII report, and effective doses obtained using the International Commission on Radiological Protection (ICRP) Report 103 organ weighting factors.
Whenever possible, the children's hospital uses rapid brain MRI to assess ventricular size of its patients with shunted hydrocephalus.



By Cynthia E. Keen

Describing the Brain in Autism in Five Dimensions

Autism spectrum disorders (ASD) are a group of biologically based neurodevelopmental disorders characterized by impairments in three major domains:

1.       socialization

2.      communication

3.       behavior

These disorders include

·         autistic disorder (classic autism, sometimes called early infantile autism, childhood autism, or Kanner's autism),

·          Rett disorder,

·          childhood disintegrative disorder,

·         pervasive developmental disorder, not otherwise specified (PDD-NOS), and

·          Asperger disorder (also known as Asperger syndrome

A recent study by Ecker et al demonstrated  how a multiparameter classification approach can be used to characterize the complex and subtle structural pattern of gray matter anatomy implicated in adults with ASD. A set of five morphological parameters including volumetric and geometric features at each spatial location on the cortical surface was used to discriminate between people with ASD and controls using a support vector machine (SVM) analytic approach and to find a spatially distributed pattern of regions with maximal classification weights.

 On the basis of these patterns, SVM was able to identify individuals with ASD at a sensitivity and specificity of up to 90% and 80%, respectively. However, the ability of individual cortical features to discriminate between groups was highly variable, and the discriminating patterns of regions varied across parameters.

Morphometric feature Correctly classified (%) Sensitivity (%) Specificity (%) p Left hemisphere     All parameters 85 90 80 0*     Cortical thickness 90 90 90 0*     Radial curvature 72.5 65 80 <0.001     Average convexity 70 75 65 <0.004     Metric distortion 80 80 80 0*     Pial area 77.5 70 85 0* Right hemisphere     All parameters 65 60 70 <0.03     Cortical thickness 60 65 55 <0.01     Radial curvature 52.5 50 55 <0.30     Average convexity 50 40 60 <0.40     Metric distortion 57.5 45 70 <0.06     Pial area 45 45 45 <0.60

 The classification was specific to ASD rather than neurodevelopmental conditions in general (e.g., attention deficit hyperactivity disorder). These results confirm the hypothesis that the neuroanatomy of autism is truly multidimensional, and affects multiple and most likely independent cortical features. The spatial patterns detected using SVM may help further exploration of the specific genetic and neuropathological underpinnings of ASD, and provide new insights into the most likely multifactorial etiology of the condition.

@The Journal of Neuroscience August 2010