Reading, Crowding, and Posterior Cortical Atrophy

Paul is a retired health care professional who has early phases of Alzheimer’s Disease (AD), but in an atypical presentation known as Posterior Cortical Atrophy (PCA).  In typical  AD, the neurodegenerative process begins with atrophy of the hippocampal regions of the brain and disrupts memory.  In contrast, PCA begins with atrophy in the posterior regions typically involving the parietal and occipital regions of the brain.

PCA vs. AD

PCA escapes early detection because the patient is still so sharp in terms of memory, receptive language, and expressive language.  The earliest signs are related to visual impairment, though not impairment in visual acuity or visual field – as the term is conventionally used.

In 2010 I blogged about Lillian, a case of PCA that Oliver Sacks popularized in The Mind’s Eye.  As with Lillian, it is sad to see Paul – a once vital practitioner and musician – progressively diminish in his visual abilities.  Paul suffered a TIA while undergoing heart surgery in 2010, and much of the focus since that time has been on trying to help him regain driving skills, and track well enough to read accurately.

While Paul’s visual acuity and visual fields have remained relatively normal, his visual tracking and visual representation of space has not improved.  We have been successful in helping his binocular vision, which had begun to unravel, but not as successful to date in helping him with his visual cognition.

A recent paper in Neuropsychologia links progressive deterioration in reading to the neurodegenerative changes in PCA, with crowding as a significant factor.  Scanning in the horizontal plane becomes particularly problematic.  The compensation for crowding is larger size font, and well-spaced letters.  Reading through a typoscope with a window; blowing up print size on eReaders; experimenting further with color and contrast are all on the agenda.  While we are going to still work in neuro-optometric rehabilitation on maximizing Paul’s residual visual abilities, his is a case in which we’ll have to continue swimming upstream with increasing vigor.


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