Clever test gives more clues about Alzheimer's disease
Scientists know mild cognitive impairment or MCI can interfere with daily functioning. In an effort to discover how even mild cognitive impairment that leads to Alzheimer’s disease affects daily living, researchers have developed a ‘clever’ new test that could lead to ways to retrain the brain.
The finding could mean increased independence for anyone on the path to Alzheimer’s and provides new insights into what processes interfere with carrying out daily activities in the presence of even mild memory deficits.
Terry Goldberg, PhD, a professor of psychiatry and behavioral science at the Hofstra North Shore-LIJ School of Medicine and director of neurocognition at the Litwin Zucker Center for Research in Alzheimer's Disease and Memory Disorders at The Feinstein Institute for Medical Research in Manhasset, NY and colleagues designed the test.
The goal is to help people who will develop Alzheimer’s disease function better in their daily lives.
Goldberg explains the test involves tapping into the semantic processing system in the brain that has broader implications for how a person functions in their daily life.
Clinicians are trained to focus on short-term memory problems when screening for cognitive impairment and Alzheimer’s disease. The researchers wanted to find out if there are other memory impairments that haven’t been picked up on before.
To perform the test, the researchers needed a test that did not rely on verbal skills. “If you ask someone what is bigger, a key or an ant, they would be slower in their response than if you asked them what is bigger, a key or a house,” explained Dr. Goldberg in a news release.
The Dartmouth College of Education explains semantic processing as understanding the meaning of words: “…you might depend in part on semantic processing to know that when you read “cat” it means or refers to that warm, furry, purring thing that jumps on your lap and meows.”
For the study, researchers tested 25 patients with MCI, 27 patients with Alzheimer's and 70 people with no memory deficits.
The finding showed major differences between cognitively fit people and those with MCI and Alzheimer’s
“This finding suggested that semantic processing was corrupted,” said Dr. Goldberg. “MCI and AD (Alzheimer's disease) patients are really affected when they are asked to respond to a task with small size differences."
For the test, the scientists used factual, competitive questions. “If you ask someone what is bigger, a key or an ant, they would be slower in their response than if you asked them what is bigger, a key or a house,” explained Dr. Goldberg.
Then they threw in images designed to require more processing by showing incongruent pictures - a small ant and a big house or a big ant and a small house.
Participants with cognitive impairment or AD became confused and took longer to answer.
Mildly impaired participants functioned somewhere in between the group with no memory deficits and those with Alzheimer’s disease.
After they identified problems with semantic processing, the researchers turned to the UCSD Skills Performance Assessment scale to find out if the subtle declines seen in memory interfere with a person’s daily functioning.
The test reveals a person’s ability to write a complex check or organize a trip to the zoo on a cold day, the researchers explain.
“The semantic system is organized in networks that reflect different types of relatedness or association,” the investigators wrote in their study. “Semantic items and knowledge have been acquired remotely, often over many repetitions, and do not reflect recent learning.”
The finding is important because it gives clues that something besides memory – in this case processing existing knowledge – is slowing down.
In an accompanying editorial David P. Salmon, PhD, of the Department of Neurosciences at the University of California in San Diego points out the test shows people who will later develop Alzheimer’s disease gradually lose their ability to process knowledge and that it happens early. He agrees the finding also shows even mild memory deficits can interfere with ‘usual activities of daily living’.
Goldberg and his team plan to continue their studies to see if semantic problems get worse as the disease progresses. The finding is published in the American Journal of Psychiatry.
Finding more clues to Alzheimer’s disease with the new test suggests retraining the brain might strengthen semantic processing. It’s not episodic memory loss that interferes with daily functioning, but instead semantic memory.
North Shore-Long Island Jewish Health System
December 27, 2012