Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Alzheimer’s disease may originate in the brain’s white matter

18.09.2002


Changes in the brain’s white matter may play a major role in the onset of Alzheimer’s disease, whose baffling origin has traditionally been blamed on the gray matter. The new findings could provide a fresh direction for Alzheimer’s research in this neglected part of the brain, offering the potential for early diagnosis and enhanced therapies.



The results are reported in the Sept. 17 print edition of Biochemistry, a peer-reviewed journal of the American Chemical Society, the world’s largest scientific society.

"Alzheimer’s disease is conventionally considered a disease of the brain gray matter because its most prominent consequence is severe memory loss," says Alex Roher, M.D., Ph.D., director of the Sun Health Research Institute in Sun City, Ariz., and lead author of the paper. The overwhelming majority of Alzheimer’s research has focused on gray matter, despite the fact that white matter makes up about 50 percent of total brain tissue and is substantially altered during Alzheimer’s progression, Roher says.


The prevailing theory has been that changes in the white matter are simply effects of the initial gray matter alterations, but Roher’s research suggests the opposite may be the case: white matter changes could come first.

In the brain, a layer of gray tissue surrounds a whitish core, like the peel of an orange around its juicy interior. The gray exterior consists of neurons and their associated neurites — short protrusions that communicate with neighboring neurons. This gray matter essentially acts as the brain’s central processor.

Neurons send messages through the brain and to the central nervous system by transmitting electrical signals over long appendages called axons. Axons are covered with an insulating fatty sheath, known as myelin, which speeds up the transmission of the signals. Myelin is the major component of white matter.

"Ours is the first study to present a detailed biochemical analysis of white matter tissue of Alzheimer’s disease patients," Roher says. The researchers studied brain tissue from two groups of people: those with autopsy-diagnosed Alzheimer’s disease, and those who died from other causes with no associated dementia.

The study revealed that the total amounts of protein, lipids and cholesterol were significantly reduced in the myelin of Alzheimer’s patients in comparison to the control group. This erosion of the myelin sheath is referred to as demyelination. "These profound white matter alterations undoubtedly contribute to the origin and development of Alzheimer’s disease, and might possibly be the initiating step," Roher says. There are multiple reasons for arriving at this conclusion, according to Roher, but two in particular stand out.

First, previous studies have demonstrated that patients with pre-clinical Alzheimer’s disease show deterioration in the white matter before the gray matter. Second, the current study suggests that white matter degeneration might be caused by a disease of the oligodendrocytes, whose main job is to produce the myelin sheath. A defective myelin coating could leave the axons unprotected, resulting in serious disturbances in nerve conduction and damage to brain functions, Roher says.

Because neurons in the gray matter are vital to cognitive activity, scientists have generally assumed that Alzheimer’s disease — with its memory loss and other cognitive debilitations — must begin in the gray matter. But Roher says the white matter is just as critical to cognitive function. White matter axons play a major role in controlling mental activities like emotion, and all mental functions are fully expressed only when the axons are transmitting properly.

An analogy can be drawn from the recent energy crisis in California, Roher says. One of the many issues facing Californians was a short supply of power — attributable, in part, to an unusually cold winter and a dry summer at hydroelectric dams. A suggested solution was to increase the output of coal-fired plants. But the state’s infrastructure — power lines, transfer stations, etc. — would be unable to carry the extra power, thus negating any potential benefits. So it is with the brain’s transmission infrastructure: the white matter.

The researchers found two other interesting relationships. Women tended to have more alterations in their white matter than men, a finding consistent with the general predominance of Alzheimer’s cases in women. An increased level of apolipoprotein E, which has been associated with higher risk of Alzheimer’s, also showed a correlation with greater demyelination.

Roher says he hopes that Alzheimer’s researchers will expand their area of interest to include white matter: "Only if the full extent of Alzheimer’s disease pathology is known will present attempts to intervene in the progression of the disease have any reasonable chance of success."

Beverly Hassell | EurekAlert!

More articles from Health and Medicine:

nachricht One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center

nachricht The gut microbiota plays a key role in treatment with classic diabetes medication
01.06.2017 | University of Gothenburg

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>