Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Alzheimer patients who scored well on memory tests – show unique compensatory brain activity

05.02.2003


Study is first link ’compensatory prefrontal network’ to better performance on memory tests



A group of Canadian researchers has found the most direct evidence to date that people with early-stage Alzheimer Disease can engage additional areas in the brain to perform successfully on memory tests.

Led by Dr. Cheryl Grady, a senior scientist with The Rotman Research Institute at Baycrest Centre for Geriatric Care, the study is published in the February 1, 2003 issue of the Journal of Neuroscience.


Alzheimer’s is a progressive, degenerative disease that affects an individual’s ability to think, remember, understand and make decisions. People with early-stage Alzheimer’s begin to experience problems with their episodic and semantic memory. Semantic refers to the accumulation of general world knowledge gained over a lifetime (for example, names of countries, famous people, major historical events). Episodic refers to events that one experiences throughout his/her life (for example, having visited the dentist yesterday, or graduating from college back in 1950).

While previous neuroimaging studies have confirmed that individuals in the early stages of the disease show ’increased’ activity in the brain’s prefrontal regions when performing cognitive tests (compared with healthy age-matched controls), Dr. Grady and her team of investigators have found the first direct link between this compensatory brain activity and successful performance on semantic and episodic memory tests.

"We found that patients who were able to recruit the prefrontal cortex of the brain ’to a greater degree’ than other patients, performed more accurately on memory tests," says Dr. Grady, who is also Professor in Psychiatry and Psychology at the University of Toronto.

While she cautioned that this compensatory effect does not last forever and diminishes as the disease progresses, she hopes her team’s findings will inspire further research. "The development of compensatory responses in relation to early cognitive changes in Alzheimer’s is an area in need of more investigation," she says. "The goal, until more definitive preventive treatment is found, is to develop more effective treatments that extend this compensatory effect and delay the degenerative effects of Alzheimer’s for longer periods."

In the study, 12 healthy older adults and 11 older patients with probable early-stage Alzheimer’s participated in a series of semantic and episodic memory tasks that were flashed on a computer screen. All of the Alzheimer’s patients were taking medication for their cognitive impairment. Participants’ brain activity was monitored using positron emission tomography (PET), which measures blood flow to various regions of the brain.

In the semantic exercise, a word or object appeared on either the right or left side of the screen, and a visual noise pattern appeared on the other side. Participants were instructed to make a living/non-living decision about each object or word by pressing the left mouse button if the object/word represented something living, and the right button if it were non-living. During the episodic recognition task, objects or words were presented on either side of the screen -- one new stimulus and one that was seen previously during the semantic task. Participants pressed the button corresponding to the side of the screen on which the ’old’ item was presented. All trials lasted four seconds, with a one-second interval blank screen.

Overall, Alzheimer’s patients performed less accurately on the semantic and episodic tasks compared to the normal, healthy controls. However, the range of scores was quite large in the Alzheimer group, with some performing poorly and others performing within the normal range. For those patients who did better on the memory tasks, researchers found that their prefrontal network activity was more expansive compared to the error-prone patients. This additional activity was happening in the right frontal and temporoparietal areas. It was a unique neural pattern not found in the normal, healthy controls either.

The study was funded by the Canadian Institutes of Health Research and the Alzheimer Society of Canada. The research team included Dr. Sandra Black, Head of Neurology and senior scientist at Sunnybrook and Women’s College Health Sciences Centre, as well as other scientists with The Rotman Research Institute at Baycrest Centre for Geriatric Care. Dr. Black is also a senior scientist at the Rotman. Baycrest is fully affiliated with the University of Toronto.

Dr. Cheryl Grady is internationally-recognized for her research which uses brain imaging to explore the functional changes that occur in aging and how these relate to changes in behaviour. In previous research, she has identified similar compensatory activity going on in the frontal regions of healthy older adults as they performed memory and recognition tests alongside younger adults. As brains age, do they find ways to compensate for cognitive decline? The answer, says Dr. Grady, could have exciting implications for memory rehabilitation.

Kelly Connelly | EurekAlert!
Further information:
http://www.baycrest.org/

More articles from Studies and Analyses:

nachricht Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University

nachricht New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>