Doctors discover that bizarre visual symptoms are a telltale sign of Alzheimer's disease

Alzheimer's disease is generally thought of as a memory-depriving disease that initially manifests as forgetfulness, difficulty remembering recent events and increasing confusion.

However, researchers have found that some people may exhibit a lesser-known early warning sign: vision problems, such as difficulty judging distances, distinguishing between moving and stationary objects, and writing.

These can go undiagnosed for years if the person only visits their ophthalmologist because too few healthcare providers know to look for them.

Doctors are trying to change that with the first-ever large-scale international study into the phenomenon known as posterior cortical atrophy (PCA), led by the University of California, San Francisco.

For the study, the team looked at the medical records of more than 1,000 PCA patients from 16 different countries.

The visuospatial symptoms of PCA begin to affect patients about five or six years earlier than patients with the more common form of Alzheimer's disease.

And while the firm number of people with PCA has not yet been determined, researchers estimate that the variant could be responsible for up to 10 percent of Alzheimer's cases, bringing the number of Americans with the condition to nearly 700,000.

PCA is a specific subtype of Alzheimer's disease and not all Alzheimer's patients will experience its symptoms, which also include problems with reading and arithmetic, using everyday objects, judging distances and recognizing faces. Memory problems may become more apparent as the disease progresses.

The average age at which symptoms typically manifest is 59 years old, six years before the average age at which Alzheimer's disease is diagnosed.

The symptoms can affect people without other memory problems, leading some to think the problems are not neurological. Deteriorating vision is a side effect of the general aging process, and many adults in their 50s and 60s are likely to attribute their vision problems to aging and, rather than seeking medical care, opt for glasses.

Much time may have passed before they finally see an ophthalmologist, who, upon noticing abnormalities in a person's vision test results, refers him or her to a neurologist who can identify the problem.

The average time between first experiencing the atypical visual symptoms and ultimately receiving a diagnosis is just under four years.

Dr. Marianne Chapleau, co-author of the paper and a researcher in the UCSF Department of Neurology, Memory and Aging Center, said: 'We need more awareness about PCA so that doctors can spot it.

'Most patients will see their optometrist if they develop visual symptoms and may be referred to an ophthalmologist who may also not recognize PCA. We need better tools in the clinical environment to identify these patients early and get them treatment.”

In the study, researchers measured the levels of two hallmarks of Alzheimer's disease: tau and amyloid proteins. Amyloid beta builds up in the brain, forming plaque deposits that are believed to cause inflammation in the body and disrupted communication between brain cells.

Tau, meanwhile, typically helps stabilize the internal structure of nerve cells in the brain. But in the case of Alzheimer's disease, abnormal chemical changes cause tau to break away from nerve cells and reattach to other tau proteins, forming threads that eventually become tangled.

People with PCA had similar levels of tau and amyloid plaques in their brains as people with the more common form of Alzheimer's.

Although there is no known cure, the common pathologies shared by Alzheimer's disease and PCA mean that PCA patients may benefit from participating in a clinical trial for one of the many drugs in the pipeline, or by speaking to their provider to talk about the anti-inhibitors approved by the Food and Drug Administration. amyloid drug lecanemab.

A better understanding of PCA is “critical for advancing both patient care and for understanding the processes that drive Alzheimer's disease,” said senior author Dr. Gil Rabinovici, director of the UCSF Alzheimer's Disease Research Center.

He added: 'It is crucial that doctors learn to recognize the syndrome so that patients can receive the correct diagnosis, guidance and care.

'From a scientific point of view, we really need to understand why Alzheimer's disease specifically targets visual and not memory areas of the brain. Our study found that 60% of patients with PCA were women. A better understanding of why they appear to be more sensitive is an important area of ​​future research.'

Their research was published in the journal Lancet Neurology.