Bizarre visual symptoms may indicate signs of Alzheimer's says study

A team of international researchers, led by UC San Francisco, has completed the first large-scale study of posterior cortical atrophy, a baffling constellation of visuospatial symptoms that present as the first symptoms of Alzheimer’s disease. These symptoms occur in up to 10% of cases of Alzheimer’s disease.

The study includes data from more than 1,000 patients at 36 sites in 16 countries. It publishes in the Lancet Neurology on Jan. 22, 2024.

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.

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; and 48% had “simultanagnosia,” an inability to visually perceive more than one object at a time. Additionally, 47% faced new challenges with basic math calculations and 43% with reading.

Reference: Do bizarre visual symptoms indicate signs of Alzheimer's?; Lancet Neurology