Neuroimaging as a Diagnostic Tool in Dementia with Lewy Bodies

Abstract

Due to similar presenting symptoms, many physicians find it difficult to distinguish cases of dementia with Lewy bodies (DLB) from Alzheimer’s disease or Parkinson’s disease with dementia. The pathologic diagnosis of DLB has improved because of the discovery of probes for α-synuclein, a protein found in Lewy bodies. However, pathologic diagnosis can be employed postmortem only, and therefore diagnostic techniques that can be employed to guide patient management are still needed. Consensus criteria have been developed for establishing a clinical diagnosis of DLB, but they lack sensitivity. Therefore, a review of the recent literature was conducted to establish whether neuroimaging studies are useful diagnostic tools to help differentiate these syndromes. At least six types of tests can be used to image the brain of patients with dementia. Structural studies (x-ray, magnetic resonance imaging and computerized tomography) can disclose the presence of stroke sequelae and other lesions, whereas functional studies (magnetic resonance spectroscopy, positron emission tomography and single-photon emission computed tomography) can disclose metabolic and blood flow alterations that may be characteristic for different types of dementia. Although more formal studies are needed to confirm that these imaging techniques are reliable diagnostic tools for DLB and permit the establishment of guidelines for their use, neuroimaging techniques currently are being employed in practice to differentiate dementia types as a guide to treatment.

Utility of the Bender Gestalt Test for Differentiation of Dementia with Lewy Bodies from Alzheimer’s Disease in Patients Showing Mild to Moderate Dementia

“…Mori et al [10] showed that the visuoperceptual disability in DLB patients plays a role in the development of visual hallucinations by a neuropsychological study. With several neuroradiological studies, DLB patients were found to exhibit a more prominent hypoactivity in the occipital lobe than AD patients, which may be responsible for visual hallucinations in DLB patients [4][5][6][7][8] . In this study, the DLB group exhibited significantly lower perfusion in the occipital and other regions than the AD group with 3DSRT, as shown in previous studies.…”

“…Neuroradiological or neuropathological studies examining such a pathomechanism in DLB patients have detected hypoactivity in the occipital lobe [4][5][6][7][8] or Lewy pathology in the secondary visual pathway [9] . On the other hand, such a pathomechanism may also be detected by neuropsychological tests examining visuoperceptual and/or constructional disabilities [10][11][12] .…”

Measurement of Gray and White Matter Atrophy in Dementia with Lewy Bodies Using Diffeomorphic Anatomic Registration through Exponentiated Lie Algebra: A Comparison with Conventional Voxel-Based Morphometry

“…These studies revealed that DLB is characterized by low glucose metabolism and decreased regional cerebral blood flow in the occipital cortex, which distinguishes it from AD. [8][9][10] On the other hand, structural changes in DLB were found to closely resemble those in AD. Volumetric studies have consistently shown a loss of GM in the MTLs, including the hippocampus and amygdala, in patients with DLB.…”

Target-Specific PET Probes for Neurodegenerative Disorders Related to Dementia

“…In DLB, a deficit in CMRglc has been observed in the temporal, parietal, occipital, and cerebral cortices (44,45). The hallucinations that are a clinical symptom of DLB are likely a correlate of a reduction of CMRglc in the primary visual cortex (46); in contrast, metabolic activity in the primary visual cortex is usually well preserved in AD.…”