Differentiation of neuropsychological features between posterior cortical atrophy and early onset Alzheimer's disease

Abstract

Background: Posterior cortical atrophy (PCA) is a group of clinical syndromes characterized by visuospatial and visuoperceptual impairment, with memory relatively preserved. Although PCA is pathologically almost identical to Alzheimer's disease (AD), they have different cognitive features. Those differences have only rarely been reported in any Chinese population. The purpose of the study is to establish neuropsychological tests that distinguish the clinical features of PCA from early onset AD (EOAD).

Methods: Twenty-one PCA patients, 20 EOAD patients, and 20 healthy controls participated in this study. Patients had disease duration of ≤4 years. All participants completed a series of neuropsychological tests to evaluate their visuospatial, visuoperceptual, visuo-constructive, language, executive function, memory, calculation, writing, and reading abilities. The cognitive features of PCA and EOAD were compared.

Results: All the neuropsychological test scores showed that both the PCA and EOAD patients were significantly more impaired than people in the control group. However, PCA patients were significantly more impaired than EOAD patients in visuospatial, visuoperceptual, and visuo-constructive function, as well as in handwriting, and reading Chinese characters.

Conclusions: The profile of neuropsychological test results highlights cognitive features that differ between PCA and EOAD. One surprising result is that the two syndromes could be distinguished by patients' ability to read and write Chinese characters. Tests based on these characteristics could therefore form a brief PCA neuropsychological examination that would improve the diagnosis of PCA.

Keywords: Cognition; Early onset Alzheimer’s disease; Neuropsychology; Posterior cortical atrophy.

Conflict of interest statement

Ethical approval and consent to participate

This study was approved by the Ethics Committee of Xuan Wu Hospital Capital Medical University; the review coding is [2015] 028. The study participants and their caregivers agreed to participate in this study, and all provided written informed consent.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

Scatter-plots representing Rey-Osterreith complex figure, writing, reading, bell cancellation, overlapping figure, Navon figure, matching test, and cookie theft picture scores for posterior cortical atrophy (PCA; n = 18), early onset Alzheimer’s disease (EOAD; n = 20), and healthy controls (Cont; n = 20)

Fig. 2

Examples of handwriting from two PCA patients. Chinese characters are abnormally formed with stroke omissions, word substitution, and unintelligible words. The first row is the sample to be copied; the second row is the copy produced by Patient 1; and the third row is the copy produced by Patient 15