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"Apperceptive" alexia in posterior cortical atrophy.

Mario F Mendez¹, Jill S Shapira, David G Clark

¹Department of Neurology, David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, CA, USA. mmendez@ucla.edu

Cortex; a Journal Devoted to the Study of the Nervous System and Behavior

|April 5, 2007

Summary

This summary is machine-generated.

Patients with posterior cortical atrophy (PCA) experience reading difficulties due to visual processing and attention deficits. This "apperceptive alexia" impacts letter identification and word reading, particularly with non-words.

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Area of Science:

Neuroscience
Ophthalmology
Cognitive Psychology

Background:

Posterior cortical atrophy (PCA) commonly presents with reading difficulty, often termed alexia without agraphia.
Alexia in PCA can stem from various causes, including visuoperceptual deficits, attentional issues, and central reading impairments.
Understanding the specific reading challenges in early PCA is crucial for diagnosis and management.

Purpose of the Study:

To evaluate the reading abilities of patients with early posterior cortical atrophy (PCA).
To compare the reading performance of PCA patients with that of normal controls.
To investigate the underlying visuoperceptual and phonological mechanisms contributing to alexia in PCA.

Main Methods:

Study included 14 patients with early PCA and reading disturbances and 14 age-matched healthy controls.
Neuroimaging confirmed occipitoparietal dysfunction in all PCA patients.
Tasks involved letter identification (with/without distractors), reading regular/irregular words, and pseudowords.

Main Results:

PCA patients exhibited errors in letter identification when letters were flanked by similar characters.
They could read most single words but struggled with visual errors and particularly with pseudowords.
A letter-by-letter reading strategy was ineffective for PCA patients, indicating impaired serial visual processing.

Conclusions:

The reading impairment in PCA, termed 'apperceptive alexia,' arises from perceptual and attentional difficulties in serial visual processing.
Impaired word configuration during letter-by-letter reading contributes to this alexia.
Difficulty with pseudowords suggests an additional deficit in phonological processing, with variable neuropathology influencing individual presentations.