Not all cases of Alzheimer’s disease begin with memory problems.
A rare form called posterior cortical atrophy (PCA) affects vision first, making it hard for people to read, navigate, or recognize objects.
Now, a new study by researchers at University College London (UCL) has uncovered key differences in the brain that may explain why some people with Alzheimer’s experience visual symptoms instead of memory loss.
Published in the journal Neuropathology and Applied Neurobiology, the study examined brain tissue donated by 26 people with PCA and 27 with typical, memory-led Alzheimer’s.
The team looked at how certain proteins and immune cells were distributed in the brain. These included amyloid and tau proteins, which are closely linked to Alzheimer’s disease, and microglia, immune cells that help clean up damaged brain cells and proteins.
In the brains of people with PCA, the researchers found more widespread buildup of amyloid and tau in the back part of the brain—the parietal region—where visual information is processed.
They also found increased microglial activity in brain areas that are usually affected in typical Alzheimer’s cases, like the sides of the brain (the temporal region). This activity could be a sign of the brain trying to fight off damage.
In contrast, people with memory-led Alzheimer’s showed the highest levels of tau in the temporal region but had lower microglial activity there. This contrast in how the brain is affected may explain why some people lose memory while others first notice problems with vision.
Dr. Zeinab Abdi, lead author of the study, said the findings suggest that where inflammation and protein buildup happen in the brain influences which symptoms appear first. This research could help scientists develop more targeted treatments and personalized care plans for people with different types of Alzheimer’s.
People with PCA tend to develop symptoms at a younger age—often in their 50s or 60s—compared to those with more typical Alzheimer’s. Dr. Abdi said learning more about these rarer forms of the disease is important for helping all patients get the care they need.
Dr. Richard Oakley from the Alzheimer’s Society added that this kind of research is vital. Dementia is the leading cause of death in the UK, and understanding the different ways it can affect people is key to developing better diagnosis tools and treatments.
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