Posterior Cortical Atrophy

What Posterior Cortical Atrophy is

Posterior Cortical Atrophy is a clinical syndrome of progressive visual and visuospatial difficulty without an eye problem to explain it. The pathology is most commonly Alzheimer's Disease, with the disease selectively affecting the parietal and occipital cortices. It is sometimes called Benson's Syndrome after the neurologist who described it.

Onset is often in the late fifties or early sixties, a decade younger than typical Alzheimer's. Memory is relatively preserved in the early stages.

How it presents

• Difficulty reading, particularly with full lines of text and tables;
• Difficulty recognising objects from unusual angles;
• Bumping into furniture; difficulty judging distances and steps;
• Difficulty pouring liquids without spilling;
• Driving difficulty (lane discipline, merging, parking);
• Trouble locating items on a busy desk or shelf;
• Difficulty using ATMs, phones with small icons, household controls;
• Falls, particularly on stairs;
• Word-finding difficulty may emerge later, but memory remains relatively preserved early.

Why it is often misdiagnosed

People with Posterior Cortical Atrophy almost always see an optician or ophthalmologist first, often repeatedly, because the symptoms feel like vision problems. Eye examination is normal; new glasses do not help. Most people are referred for memory assessment only when the broader cognitive context becomes clear, often years into the illness.

How it is diagnosed

Diagnosis combines:

• A careful history with attention to the visuospatial features;
• Examination including drawing, copying, simultaneous visual perception, navigation tasks;
• Cognitive testing showing relatively preserved memory and language, with prominent visuospatial impairment (Clock drawing, wire cube, intersecting pentagons on the ACE-III visuospatial section);
• Formal neuropsychometric assessment for the parieto-occipital pattern;
• Magnetic Resonance Imaging showing parietal and occipital atrophy (Koedam Scale useful);
• FDG-PET showing parieto-occipital hypometabolism;
• Cerebrospinal Fluid biomarkers may confirm underlying Alzheimer's Pathology.

Treatment

Cholinesterase Inhibitors are reasonable given the underlying Alzheimer's Pathology, although trial evidence in Posterior Cortical Atrophy specifically is limited. Practical interventions matter as much as medication:

• Occupational therapy and home assessment for visual safety;
• Improved lighting, contrast, clear paths;
• Removal of trip hazards;
• Voice-controlled devices (Alexa, Google Home) for control of lighting, reminders;
• Large-print books, audiobooks, screen readers;
• RNIB resources, even though formal vision is normal;
• Driving usually stopped early because of visuospatial demands.

Specialist support

Posterior Cortical Atrophy is rare enough that specialist peer support is uniquely valuable. Rare Dementia Support runs a specific PCA Support Group online and in person. The PCA Support Group is run from UCL's Dementia Research Centre.

Where The Dementia Service fits in

Posterior Cortical Atrophy is often missed in initial assessments because the cognitive profile does not look like classic Alzheimer's Disease. The Dementia Service can provide structured assessment with FDG-PET and neuropsychometric onward referral.