Neuroimaging in Dementia

Abstract

SummaryDementia is a common illness with an incidence that is rising as the aged population increases. There are a number of neurodegenerative diseases that cause dementia, including Alzheimer’s disease, dementia with Lewy bodies, and frontotemporal dementia, which is subdivided into the behavioral variant, the semantic variant, and nonfluent variant. Numerous other neurodegenerative illnesses have an associated dementia, including corticobasal degeneration, Creutzfeldt–Jakob disease, Huntington’s disease, progressive supranuclear palsy, multiple system atrophy, Parkinson’s disease dementia, and amyotrophic lateral sclerosis. Vascular dementia and AIDS dementia are secondary dementias. Diagnostic criteria have relied on a constellation of symptoms, but the definite diagnosis remains a pathologic one. As treatments become available and target specific molecular abnormalities, differentiating amongst the various primary dementias early on becomes essential. The role of imaging in dementia has traditionally been directed at ruling out treatable and reversible etiologies and not to use imaging to better understand the pathophysiology of the different dementias. Different brain imaging techniques allow the examination of the structure, biochemistry, metabolic state, and functional capacity of the brain. All of the major neurodegenerative disorders have relatively specific imaging findings that can be identified. New imaging techniques carry the hope of revolutionizing the diagnosis of neurodegenerative disease so as to obtain a complete molecular, structural, and metabolic characterization, which could be used to improve diagnosis and to stage each patient and follow disease progression and response to treatment. Structural and functional imaging modalities contribute to the diagnosis and understanding of the different dementias.Electronic supplementary materialThe online version of this article (doi:10.1007/s13311-010-0012-2) contains supplementary material, which is available to authorized users.

Molecular Brain Imaging in the Multimodality Era

“…Structural MRI for neuroimaging applications is often T 1 -and/or T 2 -weighted ( Figures 1B and 1D, row 2) with related sequences optimized for imaging of vasculature and brain pathology (Frisoni et al, 2010;Tartaglia et al, 2011). Diffusion-weighted imaging reflects water diffusivity and diffusion tensor imaging (DTI) (e.g., apparent diffusion coefficient and fractional anisotropy) assessments of white matter integrity and axonal architecture have become more routine ( Figures 1C and 1D, rows 3 and 4).…”

“…High interindividual variability in cerebral volume loss of normal aging has led to the development of brain-mapping techniques to further enable detection and tracking of atrophy in crosssectional and longitudinal studies (Thompson et al, 2004). Further comprehensive detail is available in recent reviews (Ewers et al, 2011a;Frisoni et al, 2010;Tartaglia et al, 2011).…”

“…Functional Magnetic Resonance Imaging : A large body of research has established functional alterations in brain areas linked with memory processing in AD, MCI and in some at risk for AD (APOE e4 carriers), with involvement of hippocampus and mesial temporal lobe (MTL) (Mevel et al, 2011;Tartaglia et al, 2011). In an example study, Dickerson et al (2005) applied a face-name encoding task and observed greater hippocampal activation in MCI subjects than controls, while hippocampal or entorhinal volumes were not different.…”

Degeneration of the Human Nervous System and Magnetic Resonance Neuroimaging

“…Some other forms are dementia with Lewy bodies, and frontotemporal lobal degeneration, which is subdivided into the behavioural variant (fronto-temporal dementia, FTD), the semantic dementia, primary progredient aphasia, corticobasal degeneration, progressive supranuclear palsy and amyotrophic lateral sclerosis with frontotemporal dementia. Numerous other neurodegenerative illnesses have an associated dementia, including Creutzfeldt-Jakob disease, Huntington's disease, multiple system atrophy, and Parkinson's disease dementia (Tartaglia et al,2011). dementias are acquired diseases that clinically affect cognitive abilities and daily activities.…”

A Comparison Between Volumetric Data Generated by Voxel-Based Morphometry and Manual Parcellation of Multimodal Regions of the Frontal Lobe

“…In different variants of dementia, such as Alzheimer disease or frontotemporal lobar degeneration, brain volume loss is commonly more severe than in healthy aging. 9,10 Different networks may be particularly vulnerable in different variants of dementia, 11 which has been related to pathology-specific vulnerability of certain cells or cell structures in cortex. For example, the von Economo neurons and fork cells in the anterior cingulate gyrus and frontoinsular parts of the brain have been shown to be particularly vulnerable to degeneration in the behavior variant of frontotemporal lobar degeneration.…”