When it comes to Alzheimer's research, it's always encouraging to hear when there's something you can do (or avoid doing) to slash your risk. However, some things in life are out of our control, including issues with vision—and if you don't believe your eye prescription or 20/20 vision play a role in your brain health, you'd be wrong. In a new study, a team of international researchers led by the University of California, San Francisco (UCSF) looked into visual problems that may be some of the first signs of Alzheimer's, finding that 94 percent of patients had the same issues.
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The study, which was published in Lancet Neurology on Jan. 22, is "the first large-scale study of posterior cortical atrophy" (PCA), according to a Jan. 22 press release. After studying 1,092 patients from 36 sites in 16 countries, researchers concluded that PCA—a brain and nervous system syndrome that causes issues with eyesight and processing visual information—"overwhelmingly predicts Alzheimer's."
PCA can cause difficulty judging distance, determining which objects are moving versus still, and completing tasks like writing or picking up an item you dropped. And it may not even show up on a normal eye exam, study co-first author Marianne Chapleau, PhD, of the UCSF Department of Neurology, the Memory and Aging Center, and the Weill Institute for Neurosciences, said in the release.
In total, 94 percent of study participants with PCA had Alzheimer's pathology, while the other 6 percent showed Lewy body disease and frontotemporal lobar degeneration. This is an impressive finding, as other studies that have looked at patients with memory loss found that only about 70 percent of these patients have Alzheimer's pathology.
Researchers found that patients with PCA actually had normal cognition when they first started showing PCA symptoms, typically around age 59. By the time they're diagnosed with PCA, however, which usually happens around age 63, they're more likely to be showing signs of dementia.
“We need more awareness of PCA so that it can be flagged by clinicians,” Chapleau said in the press release. “Most patients see their optometrist when they start experiencing visual symptoms and may be referred to an ophthalmologist who may also fail to recognize PCA. We need better tools in clinical settings to identify these patients early on and get them treatment.”
When diagnosed with PCA, 61 percent of patients were unable to copy or construct basic diagrams or figures (constructional dyspraxia), 49 percent weren't able to determine the location of something they say (space perception deficit), and 48 percent couldn't visually perceive more than one item at a time (simultanagnosia), the press release states. Roughly half of the participants also struggled with basic math (47 percent) and reading (43 percent).
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When compared to patients with Alzheimer's, those with PCA also had similar levels of harmful amyloid and tau plaques, but they're in a different part of the brain. This means that those with PCA could be candidates for anti-amyloid treatments, which are typically given at the earliest phases of Alzheimer's disease, co-first author Renaud La Joie, PhD, also of the UCSF Department of Neurology and the Memory and Aging Center, said in the release.
“Patients with PCA have more tau pathology in the posterior parts of the brain, involved in the processing of visuospatial information, compared to those with other presentations of Alzheimer’s. This might make them better suited to anti-tau therapies,” La Joie said.
While those with PCA aren't typically involved in clinical trials, UCSF experts are looking into treatments for these patients and patients whose memories aren't affected, La Joie added.
Overall, researchers note that it's important to understand and recognize PCA so patients receive intervention as early as possible. But in terms of how the condition is related to Alzheimer's, that's still not entirely clear.
“From a scientific point of view, we really need to understand why Alzheimer’s is specifically targeting visual rather than memory areas of the brain," senior study author Gil Rabinovici, MD, director of the UCSF Alzheimer’s Disease Research Center, said in the release. "Our study found that 60% of patients with PCA were women—better understanding of why they appear to be more susceptible is one important area of future research.”
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