Constructional Apraxia in Alzheimer’s Disease: Association with Occipital Lobe Pathology and Accelerated Cognitive Decline

Abstract

The functional impact and progression of occipital lobe pathology in sporadic late onset Alzheimer’s disease (AD) is barely explored. It is accepted that the primary and association visual areas are affected relatively late, in the neocortical stages of AD. We analysed 60 prospectively assessed AD patients in whom global cognitive deterioration and constructional apraxia were evaluated longitudinally using the CAMDEX. Radioactive immunohistochemistry was used to assess the amount of AD-related pathology in Brodmann areas 18 and 17. Braak staging of each case was also carried out. This study showed that in AD patients constructional apraxia is associated with higher expression of hyperphosphorylated tau. Additionally our findings indicate that early constructional apraxia is a predictor of accelerated cognitive decline in AD.

Neuropsychological Differences Between Frontotemporal Dementia and Alzheimer's Disease: A Review

“…Visuospatial deficits are among the earliest manifestations of AD. Patients have particular problems with drawing, constructions, and orientation in their own surrounding (Mendez and Cummings, 2003;Mendez et al, 1990b;Smith et al, 2001). Although the previously described CDT is one of the most widely used instruments sensitive to visuospatial impairment, it is often applied as a general measure of cognitive decline since it engages more than visuospatial functions.…”

Visual Perceptual Organization Deficits in Alzheimer’s Dementia

“…Patients with AD are characterized by pronounced deficits in visual processing as indicated by the presence of visual agnosia and apraxia, reading difficulties and spatial disorientation [12] . Experimental studies have reported impairments in object recognition [13] , facial recognition [14] , and visuospatial abilities [15] . In addition to deficits in higher-level visual perception, there is evidence for impairment of early visual mechanisms such as reduced contrast sensitivity [16] and backward masking [12] .…”

Damage to the Frontal Aslant Tract Accounts for Visuo-Constructive Deficits in Alzheimer’s Disease

“…Such deficits are typically observed in patients with focal brain lesions [39], but they can also be present in patients with neurodegenerative conditions, such as AD [24,25,42,43] or frontotemporal dementia [23]. Despite its precise anatomical-functional localization being still under debate [24,25,41,44,45], constructional apraxia is generally observed in patients with parietal [39] or frontal lobe [23] damages.…”