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| CREDIT: © Laurin Rinder | Dreamstime.com |
Which is bigger, a key or an ant? That question might be
easy for you to answer quickly, but it could be a little more confusing for a
person with Alzheimer's. The most obvious trait of the mind-ruining disease is
memory loss, with patients forgetting once-familiar people, places and
experiences. New research shows how this mental deterioration extends to
semantic memory, which has more to do with remembering facts and concepts and
underlies a basic understanding of how things works.
For their study, researchers recruited 70 cognitively
healthy people, 27 patients with Alzheimer's 25 patients with mild cognitive
impairment (MCI), often considered a precursor to dementia. All were tested on
their ability to make size judgments about two pictures shown to them — the
premise being that the bigger the difference in size between two objects, the
faster a person would be able to answer the question. "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," researcher Terry
Goldberg, of the Hofstra North Shore-LIJ School of Medicine, said in a
statement.
This held true in the experiments, but the MCI and
Alzheimer's patients had much more trouble when asked to respond to a task with
small size differences. The experiment was then tweaked so that the
participants were shown pictures of a small ant and a big house or a big ant
and a small house. The MCI and Alzheimer's patients did not have a problem
making judgments about the small ant and big house, but had trouble with the
more incongruent set. They were confused about which object was actually larger
when shown a big ant and a small house, and were more likely to answer
incorrectly or take longer to arrive at a response, the researchers said.
Goldberg said the findings indicate "that something
is slowing down the patient and it is not episodic memory but semantic
memory." The team will continue to study these patients over time to see
if these semantic problems get worse as the disease advances. The research was
detailed this month in the American Journal of Psychiatry.
Source: Live Science
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