New Research Suggests That PCA, A Complex Array Of Vision Issues, Is An Early Indicator Of Alzheimer’s Disease, Calling For Improved Clinician Screening To Aid Early Detection
Alzheimer’s disease, widely known as the most prevalent type of dementia, is marked by distressing and debilitating symptoms like forgetfulness, persistent memory loss, confusion, and, ultimately, a loss of the ability to independently manage daily activities.
Additionally, a recent study has highlighted a lesser-known early stage of dementia symptoms known as posterior cortical atrophy, or PCA.
PCA presents a complex array of visuospatial symptoms that often emerge as initial indicators of Alzheimer’s disease. Researchers at UC San Francisco recently completed the first extensive study on PCA, and now, they report that up to 10% of Alzheimer’s cases exhibit PCA symptoms.
This research analyzed data from more than 1,000 patients across 36 locations in 16 nations. In essence, the study suggests a strong link between posterior cortical atrophy (PCA) and Alzheimer’s disease.
An overwhelming 94% of those with PCA showed signs of Alzheimer’s, while the remaining 6% were affected by other disorders like frontotemporal lobar degeneration and Lewy body disease. In contrast, other research indicates that around 70% of individuals with memory loss are found to have Alzheimer’s pathology.
Unlike those with memory issues, individuals with PCA face challenges in estimating distances, differentiating between objects in motion and those at rest, and performing tasks like writing or retrieving a dropped item.
But, according to Marianne Chapleau from the UCSF Department of Neurology, Memory and Aging Center, most PCA patients can still pass a standard eye test despite their visual challenges.
Initially, a majority of PCA patients showed normal cognitive abilities. However, by their first diagnostic appointment– averaging 3.8 years after the onset of symptoms– they often exhibited mild or moderate dementia. This was evident in various areas, including executive function, memory, behavior, speech, and language.
When diagnosed, 61% of the patients showed signs of “constructional dyspraxia,” which means they couldn’t replicate or create simple diagrams or figures.
goodluz – stock.adobe.com – illustrative purposes only, not the actual person
Additionally, 49% experienced a “space perception deficit,” having trouble pinpointing the location of visible objects, and 48% had “simultanagnosia,” the inability to visually process multiple objects simultaneously. Furthermore, 47% faced new difficulties with basic mathematical calculations, and 43% had problems with reading.
“We need more awareness of PCA so that it can be flagged by clinicians. 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,” Chapleau explained.
“We need better tools in clinical settings to identify these patients early on and get them treatment.”
It’s also crucial to note that the average age for the onset of PCA symptoms is 59 years old, which is notably younger than the typical age for an Alzheimer’s diagnosis. So, this difference in age at onset is another factor that leads to the lower likelihood of PCA patients receiving a diagnosis.
Renaud La Joie, the study’s co-first author, emphasized that early detection of PCA could be crucial for Alzheimer’s treatment. In the study, the levels of amyloid and tau– identified in cerebrospinal fluid and through imaging, as well as autopsy findings– were consistent with those observed in typical Alzheimer’s patients.
As a result, PCA patients might benefit from anti-amyloid treatments like lecanemab– or Leqembi– which received U.S. FDA approval in January 2023 and anti-tau therapies that are currently under clinical trials. Both treatment strategies are likely to be more effective in the early stages of the disease.
“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 detailed.
Still, following the completion of this study, senior author Gil Rabinovici is calling for further research.
“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,” Rabinovici concluded.
“Our study found that 60% of patients with PCA were women– a better understanding of why they appear to be more susceptible is one important area for future research.”
To read the study’s complete findings, which have since been published in The Lancet Neurology, visit the link here.
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