Vision problems specific to Alzheimer's disease can be an early sign of the disease

For some patients with Alzheimer's, the early signs of the disease are not memory loss; Visual impairment Due to an unknown variant of pathology:Posterior cortical atrophy (PCA) . These unusual symptoms can occur It is difficult to diagnose Right, which can arrive years late for thousands of people. Until now, little was known about posterior cortical degeneration, but a large, first-of-its-kind international study led by researchers at the University of California, San Francisco, was published in 2017. Lancet Neurology He comprehensively studied this variant of Alzheimer's disease. The University of Trento, the Vita e Salute University of San Raffaele in Milan with Professor of Neuroscience Federica Agosta, and the University of Milan with Professor Daniela Galimberti from the Department of Biomedicine, Surgery and Dentistry also participated in the work.

PCA may affect up to 10% of Alzheimer's patients

Scientists studied data from 1,092 PCa patients from 16 different countries around the world and found that on average, the syndrome begins to affect Patients aged 59 yearsThat is, approximately 5-6 years earlier than most patients with the most common form of Alzheimer's disease. It has been observed in the work that approximately 94% of patients with PCa have Alzheimer's disease while the remaining 6% are affected by conditions such as Lewy body disease and frontotemporal dementia.

It has not been possible to determine how many people have posterior cortical atrophy, but researchers estimate that they may develop posterior cortical atrophy.It accounts for up to 10% of all Alzheimer's cases. The authors of the work hope that increased awareness of the syndrome will help doctors diagnose it earlier and encourage researchers to include patients with posterior cortical atrophy in clinical trials for Alzheimer's disease. “One thing we discovered from our study – confirms Jill D. “When the disease is diagnosed, patients are affected for many years and so there is a lot of work to be done to raise awareness of the syndrome.”

60% of patients are women

The study, which began in 2021, found that PCa is being diagnosed on average Only four years after visual symptoms appeared, when signs of memory loss also begin to appear. However, the progression of the disease is variable: some patients show a decline in memory one or two years after the onset of visual symptoms. Research has also found that PCa patients have accumulations Plaques of amyloid and tau proteins Like those observed in the most common form of Alzheimer's disease, but in a different area of ​​the brain, specifically in the back, in the areas responsible for processing visual information. For reasons that are not clear, a particularly large number Of patients: women: about 60%.

symptoms

The most common first symptoms relate to Difficulty reading and driving. Motorists with PCa have Difficulty estimating distances. Others have difficulty reading at night or… Distinguishing between fixed objects and moving objects s They cannot perceive more than one object at the same time. Some patients experience hallucinations. Other symptoms may include difficulty doing arithmetic or spelling, and many people with posterior cortical atrophy experience anxiety, perhaps because they know something is wrong. “These patients report that they do not see objects in one area of ​​the visual field, that they do not recognize multiple objects together and often do not perceive the distances between one object and another. All conditions have nothing to do with eye function,” he emphasizes. Paolo Nucci, professor of ophthalmology at Milan State University and department fellow of one of the study's authors, Daniela Galimberti. In the early stages of posterior cortical degeneration, most people do not experience significant memory impairment, but memory may be impaired in later stages.

The path to diagnosis

Since the first symptoms are visual, patients initially go to a general practitioner, then to an ophthalmologist, then to an ophthalmologist, and only finally to a neurologist. Diagnosis is now possible through cognitive ability tests or automated examinations such as brain magnetic resonance imaging (MRI) or computed tomography (CT). «The first medical examination for non-specific visual symptoms is performed with an ophthalmologist – confirms Paolo Nucci, who is also President of the Italian Society of Pediatric Ophthalmology and Strabismus – who certifies that the eye, functionally, has normal capabilities and there are no problems with image doubling or changes in the visual field that could justify asymmetries, that is, situations in which visual perception changes . In general, most ophthalmologists, during the visit, It is immediately understood whether visual perceptions are of a peripheral nature, i.e. visual, or whether visual perceptions are of a central nature, i.e. neural area. It is good to have close cooperation between the ophthalmologist and the neurologist. However, be careful not to panic too much: some of these symptoms may be related to vascular lesions in the posterior region of the brain.

How to relieve symptoms

Come to Alzheimer's There is no definitive cure for posterior cortical atrophy But low vision services can help these patients. To make it easier to see, you can read books with larger print, use stronger and better lighting in your home and highlight uneven surfaces, such as stairs, with fluorescent tape. Some patients may benefit from treatments aimed at improving symptoms of Alzheimer's disease such as cholinesterase inhibitors or NMDA receptor antagonists. “Early identification of PCa could have important implications for the treatment of Alzheimer's disease,” said Renaud La Joye, MD, a neurologist and first author of the study. Thus, these patients could also be candidates for anti-amyloid therapies currently used only in the United States or for anti-tau therapies, which are currently in an experimental phase.

Terry Pratchett case

Posterior cortical atrophy was first described in the medical literature in just five patients in 1988, but for a long time the syndrome was not well understood and experts around the world did not use the same diagnostic criteria. Only in 2017 did scientists agree on a single description of the condition, publishing it in the journal Alzheimer's and dementia. The lack of knowledge about the disease goes back to British writer Terry Pratchett, author of the Discworld series, who died in 2015, and who announced in 2007 that he had been diagnosed with a rare form of Alzheimer's associated with posterior cortical degeneration.