Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

SFVAMC researchers distinguish dementias using brain imaging

12.08.2003


Study suggests hope for better treatment of Alzheimer’s and stroke



Until now, scientists have been unable to distinguish between dementia caused by Alzheimer’s disease and that caused by poor blood flow to the brain. But, researchers at the San Francisco VA Medical Center have now used a combination of magnetic resonance imaging (MRI) and a related technique knows as MR spectroscopy to differentiate between the two kinds of dementia. Their work offers hope of improving the treatment of dementia in patients with poor blood flow, such as stroke victims, and the testing of drugs to treat Alzheimer’s disease (AD).

"Currently, there are no effective treatments for Alzheimer’s disease, but we do have options for treating vascular disease. So, being able to determine that there is a vascular component to a patient’s dementia would make a big difference in planning for treatment," said Norbert Schuff, PhD, a researcher in the Magnetic Resonance Unit at the San Francisco VA Medical Center and a UCSF associate professor of radiology.


The findings of the current study, appearing in the August 12 issue of Neurology, also promise to help speed up the development of new drug therapies for AD. "If we can tell the difference between people with Alzheimer’s and those with vascular dementia, we can select the appropriate candidates for clinical trials of new drugs," said Schuff, who is lead author of the current study.

Alzheimer’s disease, which affects 4 million Americans over the age of 65, is the most common cause of age-related dementia. It is characterized by progressive decline of cognitive functions. The second leading cause of dementia in the United States is the disruption of blood flow to the brain, known as vascular dementia. It affects between 2 and 3 percent of the U.S. population over the age of 65 years, or about 1 million people. Just as poor circulation in the heart leads to heart attacks, restricted blood flow in the brain can lead to strokes of varying severity.

Schuff and his colleagues studied the brains of 43 elderly patients who had been diagnosed with AD and 13 patients who had suffered small strokes below the surface of the brain, and diagnosed with what is called subcortical ischemic vascular dementia, or SIVD. They compared these subjects to 52 cognitively normal elderly subjects.

The researchers used MRI to create three-dimensional images of the patients’ brains in order to look for differences in structure. They also used magnetic resonance spectroscopy to look at the chemical signature of different brain regions. In particular, they looked for a by-product of particular brain cells, called neurons, that make up the wiring of the brain. Active neurons carry electrical signals between different regions of the brain and produce a chemical called N-acetylaspartate, or NAA, which is not produced by other types of brain cells. The amount of NAA in a given region of the brain indicates the level of healthy neurons in that region. A reduction in NAA suggests either neuronal loss or dysfunction.

Researchers found that patients with SIVD had less of the NAA chemical in the region of the brain involved in short-term memory and decision making, called the frontal cortex, when compared to both patients with AD and control subjects. The brains of those with SIVD also had less NAA in the area of the brain involved in language and spatial orientation, called the parietal cortex, when compared to patients with AD and controls. But, SIVD patients had virtually no NAA losses in another brain region involved in memory, called the medial temporal lobe, where patients with AD had substantial NAA deficits.

Accuracy in separating cases of SIVD from AD was improved from 79 percent to 89 percent when researchers added measures taken by MR spectroscopy to measurements taken by conventional MRI.

In patients with SIVD, Schuff and his colleagues also found that lower levels of NAA in outer parts of the brain, called the cortex, were associated with severity of strokes in the layers below the cortex, called white matter. This observation agreed with preliminary findings by other researchers suggesting that SIVD is the result of disconnections between the outer and inner portions of the brain.

This finding suggests that, in patients with SIVD, there may only be neuronal dysfunction rather than neuronal loss, offering hope for recovery of neuronal function in these areas through drug treatment and other forms of therapy, Schuff said. However, there is still the possibility that neuronal loss in SIVD is due to processes indirectly related to stroke that also result in lower NAA. More study in this area will be necessary, Schuff said.

In fact, replication of the current study is also needed, Schuff said. "These patients were very carefully selected. We need to see if this method for distinguishing vascular dementia from Alzheimer’s can be done in a clinical setting where many other factors may contribute dysfunction in the brain," he said.


Additional authors include Michael W. Weiner, MD, director of the Magnetic Resonance Unit (MRU) at the SFVAMC and UCSF professor of radiology, medicine, psychiatry and neurology; Antao Du, MD, and Diane L. Amend, PhD, both researchers of SFVAMC’s MRU; David Norman, MD, UCSF professor of radiology; Joel H. Kramer, PsyD, UCSF clinical associate professor of psychiatry; Bruce L. Miller, MD, UCSF professor of neurology; Kristine Yaffe, MD, SFVAMC chief of geriatric psychiatry and UCSF associate professor of neurology, psychiatry and epidemiology and biostatistics; Bruce R. Reed, MD, UC Davis associate professor of psychiatry; Joseph O’Neill, PhD, UC Los Angeles assistant professor of radiology; William J. Jagust, MD, UC Davis professor and chair of neurology; Helena C. Chui, MD, University of Southern California professor of neurology; and Andres A. Capizzano, MD, of the MRI Unit of Fernandez Hospital, Bueonos Aires, Argentina.

This study was funded by grants from the Department of Veterans Affairs and a grant to the Northern California Institute for Research and Education from the National Institutes of Health.

Camille Mojica Rey | EurekAlert!
Further information:
http://www.ucsf.edu/

More articles from Health and Medicine:

nachricht Illinois team develops first of a kind in-vitro 3D neural tissue model
11.12.2019 | University of Illinois College of Engineering

nachricht Safer viruses for vaccine research and diagnosis
11.12.2019 | University of Queensland

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Self-driving microrobots

11.12.2019 | Materials Sciences

Innovation boost for “learning factory”: European research project “SemI40” generates path-breaking findings

11.12.2019 | Information Technology

Molecular milk mayonnaise: How mouthfeel and microscopic properties are related in mayonnaise

11.12.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>