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Scientists Discover New Telltale Sign of Alzheimer’s

"Posterior cortical atrophy is a rare, visual variant of Alzheimer's disease. It affects areas in the back of the brain responsible for spatial perception, complex visual processing, spelling and calculation." – University of California San Francisco Memory and Aging Center

SCITECH DAILY – An international team led by the University of California, San Francisco, has carried out the first large-scale study on posterior cortical atrophy.

This condition is characterized by a perplexing set of symptoms related to visual and spatial abilities, which are among the initial indicators of Alzheimer’s disease, manifesting in as many as 10% of Alzheimer’s cases.

The study includes data from more than 1,000 patients at 36 sites in 16 countries. It was recently published in the journal Lancet Neurology.

Posterior cortical atrophy (PCA) overwhelmingly predicts Alzheimer’s, the researchers found. Some 94% of the PCA patients had Alzheimer’s pathology and the remaining 6% had conditions like Lewy body disease and frontotemporal lobar degeneration.

In contrast, other studies show that 70% of patients with memory loss have Alzheimer’s pathology.

“People with PCA may often go to see an eye doctor first, thinking that their difficulties are due to a problem with their eyes … [However], in people with PCA, the visual problems are not due to problems with their eyes. Rather, the shrinking brain can no longer interpret and process the information received from the person’s healthy eyes.”

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Unlike memory issues, patients with PCA struggle with judging distances, distinguishing between moving and stationary objects, and completing tasks like writing and retrieving a dropped item despite a normal eye exam, said co-first author Marianne Chapleau, Ph.D., of the UCSF Department of Neurology, the Memory and Aging Center and the Weill Institute for Neurosciences.

Most patients with PCA have normal cognition early on, but by the time of their first diagnostic visit, an average 3.8 years after symptom onset, mild or moderate dementia was apparent with deficits identified in memory, executive function, behavior, and speech and language, according to the researchers’ findings.

At the time of diagnosis:

– 61% demonstrated “constructional dyspraxia,” an inability to copy or construct basic diagrams or figures;

– 49% had “space perception deficit,” difficulties identifying the location of something they saw;

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– 48% had “simultanagnosia,” an inability to visually perceive more than one object at a time;

– 47% faced new challenges with basic math calculations and 43% with reading.

We need better tools and training to identify patients

“We need more awareness of PCA so that it can be flagged by clinicians,” said Chapleau …

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