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 NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures
17.11.2017 | National Institute of Standards and Technology (NIST)

nachricht High speed video recording precisely measures blood cell velocity
15.11.2017 | ITMO University

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>