title: A longitudinal investigation of the relationship between crowding and reading: A neurodegenerative approach.
abstract: We have previously documented two patients (FOL and CLA) with posterior cortical atrophy who achieved accurate and rapid reading despite deficits in ten measures of visual processing, with two notable exceptions: (1) a measure of visual acuity, (2) a measure of visual crowding. Subsequent longitudinal investigation of these patients was carried out, involving annual tests of early visual, visuoperceptual and visuospatial processing and assessment of reading ability. Follow-up assessments identified the evolution of a particular early visual processing deficit, excessive visual crowding; this deficit has been previously implicated in forms of dyslexia. Consistent with the link between crowding and reading dysfunction, follow-up assessments also revealed deterioration in both patients' reading ability. The current findings demonstrate a neurodegenerative approach towards understanding the relationship between visual crowding and the reading system, and suggest possible mechanisms for how excessive crowding may disrupt word recognition.
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK. Electronic address: keir.yong@ucl.ac.uk.
authors.forename: Keir
authors.initials: K
authors.lastname: Yong
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK.
authors.forename: Kishan
authors.initials: K
authors.lastname: Rajdev
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Warrington
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nicholas
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Warren
authors.affiliation: Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Crutch
mesh_terms: D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D003441:Crowding / Q000523:psychology*; D004192:Discrimination, Psychological; D004410:Dyslexia / Q000209:etiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000150:complications* / Q000000981:diagnostic imaging / Q000523:psychology*; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011569:Psychiatric Status Rating Scales; D013028:Space Perception / Q000502:physiology*
keywords: Alzheimer's disease (AD); Dyslexia; Letter-by-letter reading; Posterior cortical atrophy (PCA); Visual crowding