Cognitive rehabilitation in a visual variant of Alzheimer's disease

Global Brain Involvement in Posterior Cortical Atrophy: Multimodal MR Imaging Investigation

Posterior cortical atrophy (PCA), considered a visual variant of Alzheimer's disease, has similar pathological characteristics yet shows a selective visual manifestation with relative preservation of other cortical areas, at least at early stages of disease. Using a gamut of imaging methods, we aim to evaluate the global aspect of this relatively local disease and describe the interplay of the involvement of the different brain components. Ten PCA patients and 14 age-matched controls underwent MRI scans. Cortical thickness was examined to identify areas of cortical thinning. Hippocampal volume was assessed using voxel-based morphometry. The integrity of 20 fiber tracts was assessed by Diffusion Tensor Imaging. Regions of difference in global functional connectivity were identified by resting-state fMRI, using multi-variant pattern analysis. Correlations were examined to evaluate the connection between grey matter atrophy, the network changes and the disease load. The patients presented bilateral cortical thinning, primarily in their brains' posterior segments. Impaired segments of white matter integrity were evident only within three fiber tracts in the left hemisphere. Four areas were identified as different in their global connectivity pattern. The visual network-related areas showed reduced connectivity and was correlated to atrophy. Right Broadman area 39 showed in addition increased connectivity to the frontal areas. Global structural and functional imaging pointed to the highly localized nature of PCA. Functional connectivity followed grey matter atrophy in visual regions. White matter involvement seemed less prominent, however damage is directly related to presence of disease and not mediated only by grey matter damage.

Diagnostic evaluation and monitoring of patients with posterior cortical atrophy

Posterior cortical atrophy (PCA) is a progressive neurocognitive syndrome, most commonly associated with the loss of complex visuospatial functions. Diagnosis is challenging, and international consensus classification and nomenclature for PCA subtypes have only recently been reached. Presently, no established treatments exist. Efforts to develop treatments are hampered by the lack of standardized methods to monitor illness progression. Although measures developed from work with Alzheimer's disease and other dementias provide a foundation for diagnosing and monitoring progression, PCA presents unique challenges for clinicians counseling patients and families on clinical status and prognosis, and experts designing clinical trials of interventions. Here, we review issues facing PCA clinical research and care, summarize our approach to diagnosis and monitoring of disease progression, and outline ideas for developing tools for these purposes.

Posterior cortical atrophy: a single case cognitive and radiological follow-up

Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome characterized by initial predominant visuoperceptual deficits followed by a progressive decline in other cognitive functions. This syndrome has not been as thoroughly described as other dementias, particularly from a neuropsychological evolution perspective with only a few studies describing the evolution of its cognitive progression. In this investigation we review the literature on this rare condition and we perform a 7-year neuropsychological and neuroradiological follow-up of a 64-year-old man with PCA. The subject's deficits initially appeared in his visuoperceptual skills with later affectation appearing in language and other cognitive functions, this being coherent with the patient's parieto-temporal atrophy evolution.

Non-pharmacological intervention for posterior cortical atrophy

Posterior cortical atrophy (PCA) is a rare neurodegenerative condition characterized by progressive visual-perceptual deficits. Although the neurocognitive profile of PCA is a growing and relatively well-established field, non-pharmacological care remains understudied and to be widely established in clinical practice. In the present work we review the available literature on non-pharmacological approaches for PCA, such as cognitive rehabilitation including individual cognitive exercises and compensatory techniques to improve autonomy in daily life, and psycho-education aiming to inform people with PCA about the nature of their visual deficits and limits of cognitive rehabilitation. The reviewed studies represented a total of 7 patients. There is a scarcity of the number of studies, and mostly consisting of case studies. Results suggest non-pharmacological intervention to be a potentially beneficial approach for the partial compensation of deficits, improvement of daily functionality and improvement of quality of life. Clinical implications and future directions are also highlighted for the advancement of the field, in order to clarify the possible role of non-pharmacological interventions, and its extent, in PCA.

Role of RAGE in Alzheimer's Disease

Receptor for advanced glycation end products (RAGE) is a receptor of the immunoglobulin super family that plays various important roles under physiological and pathological conditions. Compelling evidence suggests that RAGE acts as both an inflammatory intermediary and a critical inducer of oxidative stress, underlying RAGE-induced Alzheimer-like pathophysiological changes that drive the process of Alzheimer's disease (AD). A critical role of RAGE in AD includes beta-amyloid (Aβ) production and accumulation, the formation of neurofibrillary tangles, failure of synaptic transmission, and neuronal degeneration. The steady-state level of Aβ depends on the balance between production and clearance. RAGE plays an important role in the Aβ clearance. RAGE acts as an important transporter via regulating influx of circulating Aβ into brain, whereas the efflux of brain-derived Aβ into the circulation via BBB is implemented by LRP1. RAGE could be an important contributor to Aβ generation via enhancing the activity of β- and/or γ-secretases and activating inflammatory response and oxidative stress. However, sRAGE-Aβ interactions could inhibit Aβ neurotoxicity and promote Aβ clearance from brain. Meanwhile, RAGE could be a promoting factor for the synaptic dysfunction and neuronal circuit dysfunction which are both the material structure of cognition, and the physiological and pathological basis of cognition. In addition, RAGE could be a trigger for the pathogenesis of Aβ and tau hyper-phosphorylation which both participate in the process of cognitive impairment. Preclinical and clinical studies have supported that RAGE inhibitors could be useful in the treatment of AD. Thus, an effective measure to inhibit RAGE may be a novel drug target in AD.