Posterior Cortical Atrophy: Advice for Diagnosis and Implications for Management

Abstract

The clinical presentation of Alzheimer's disease (AD) is heterogeneous, especially in individuals with an early age at onset, where the presenting symptoms may be language, behavior or visual impairment. Posterior cortical atrophy (PCA) refers to a syndrome where visual processing and other posterior functions are the initial symptoms. While the majority of PCA cases reflect the underlying AD, a proportion of cases are caused by dementia with Lewy bodies, corticobasal degeneration or prion disease. PCA is sometimes not recognized until late into the disease or misattributed to anxiety or malingering owing to its low frequency, the early age at onset and the relatively atypical symptoms. This article describes the PCA syndrome, emphasizing its clinical features and how it relates to early-onset AD variants. In order to aid identification of this syndrome, the neuroimaging and neuropsychological features, as well as biomarkers of the underlying pathology, are also described briefly. Finally, the implications for treatment, compensatory strategies and rehabilitation, as well as management of comorbidities, are discussed.The clinical presentation of Alzheimer's disease (AD) is heterogeneous, especially in individuals with an early age at onset.Presenting symptoms of AD may include primary impairments of language, behavior or vision.Posterior cortical atrophy (PCA) is characterized by progressive impairment in visuospatial and visuoperceptual function, alexia, and features of Balint's and Gerstmann's syndrome.The majority of PCA cases are due to AD histopathology; however, dementia with Lewy bodies, cortical basal degeneration and prion disease can all lead to a similar syndrome.In PCA, gray matter atrophy is seen on T 1 MRI in parietal, occipital and occipitotemporal cortices.Biomarkers such as cerebrospinal fluid, amyloid-b:tau ratio and amyloid PET imaging can indicate the underlying pathology.It is important to identify the underlying pathology in view of future protein-specific treatments and trials.It is important to differentiate clinical syndromes in order to provide carers and patients with relevant information and appropriate compensatory or rehabilitative strategies.

Effects of lighting variability on locomotion in posterior cortical atrophy

“…Cortico‐visual impairments arising in PCA, and to a lesser extent in typical, amnestic AD (tAD), include visuospatial and visuoperceptual deficits, diminished depth perception, and restrictions in the effective visual field 9,15–18 . PCA is associated with environmental disorientation and has profound implications for independence, safety, and care considerations 19 . At a relatively early stage, PCA patients may be unable to drive, read, dress independently, or reliably navigate familiar environments despite relatively preserved memory, language, and insight 20…”

“…Environmental adaptations have been recommended to support individuals living with dementia, particularly for PCA patients and AD patients with memory and visuospatial presentations 19,21,22 . Recommendations based predominantly on professional guidance include strategic use of signage, contrast and salient visual features, patterned flooring, glare, and clutter 2,19,23–25 .…”

“…Environmental adaptations have been recommended to support individuals living with dementia, particularly for PCA patients and AD patients with memory and visuospatial presentations 19,21,22 . Recommendations based predominantly on professional guidance include strategic use of signage, contrast and salient visual features, patterned flooring, glare, and clutter 2,19,23–25 . Lighting modulates contrast, perceived clutter, and visual saliency, factors particularly influencing object recognition and gaze location in PCA, 26,27 and lighting‐based interventions may promote functional outcomes and fall reductions in patients with all‐cause dementia 23,28 …”

“…Misperception of shadows has been reported in PCA and later‐stage AD 19,24 and is associated with hesitation or disorientation during navigation 4 . Correspondingly, approaches to maintain uniformity of lighting and minimize shadows have been recommended in various forms 23,24,29 .…”

Health and social care practitioners' understanding of the problems of people with dementia‐related visual processing impairment

“…Core features of PCA cases include relatively well‐preserved memory and language, and some insight into the difficulties they encounter in the earlier stages of the disease (Ahmed et al, ; Crutch et al, ). People with a diagnosis of PCA are therefore more likely to be able to articulate their problems with everyday activities, and may demonstrate increased responsiveness to interventions such as simple environmental changes (Shakespeare, Crutch, & Fox, ); Shakespeare et al (). Effective support from health and social care professionals can only be given if the professionals have an informed understanding of the problems of people with PCA.…”