Lewy body dementias (LBDs) consist of dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD), which are clinically similar syndromes that share neuropathological findings with widespread cortical Lewy body deposition, often with a variable degree of concomitant Alzheimer pathology. The objective of this article is to provide an overview of the neuropathological and clinical features, current diagnostic criteria, biomarkers, and management of LBD. Literature research was performed using the PubMed database, and the most pertinent articles were read and are discussed in this paper. The diagnostic criteria for DLB have recently been updated, with the addition of indicative and supportive biomarker information. The time interval of dementia onset relative to parkinsonism remains the major distinction between DLB and PDD, underpinning controversy about whether they are the same illness in a different spectrum of the disease or two separate neurodegenerative disorders. The treatment for LBD is only symptomatic, but the expected progression and prognosis differ between the two entities. Diagnosis in prodromal stages should be of the utmost importance, because implementing early treatment might change the course of the illness if disease-modifying therapies are developed in the future. Thus, the identification of novel biomarkers constitutes an area of active research, with a special focus on α-synuclein markers.
DLB | 1 | PDD | 2 | ||||
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Central features | Essential for a diagnosis: Dementia, in early stages with memory impairment, may not necessarily occur but is usually evident with progression. Deficits in tests of attention, executive function, and visuoperceptual ability may be especially prominent and occur early. | Core Features (I) | Essential for a diagnosis (both must be present): Diagnosis of Parkinson disease according to Queen Square Brain Bank criteria and Dementia syndrome with impairment in more than one cognitive domain | ||||
Core clinical features | The first three typically occur early and may persist throughout the course: |
| Associated clinical features (II) |
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| PDD; lack of behavioral symptoms, however, does not exclude the diagnosis | ||||||
Supportive clinical features | Severe sensitivity to antipsychotic agents; postural instability; repeated falls; syncope or other transient episodes of unresponsiveness; severe autonomic dysfunction, e.g., constipation, orthostatic hypotension, urinary incontinence; hypersomnia; hyposmia; hallucinations in other modalities; systematized delusions; apathy, anxiety, and depression. | None of the group (III) features present | Features which do not exclude PDD, but make the diagnosis uncertain: |
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Indicative biomarkers |
| None of the group (IV) features present | Features suggesting other conditions or diseases as cause of mental impairment, which, when present, make it impossible to reliably diagnose PDD: 1. Cognitive and behavioral symptoms appearing solely in the context of other conditions such as acute confusion due to (a.) systemic diseases or abnormalities (b.) drug intoxication 2. Major Depression according to DSM IV |
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Supportive biomarkers |
| Supportive or indicative biomarkers |
No supportive or indicative biomarkers are needed for the diagnosis of PDD as per Emre et al. (2007) diagnostic criteria. | ||||
Diagnosis of probable or possible DLB |
Probable: (a) ≥2 core clinical features of DLB are present, with or without the presence of indicative biomarkers, OR (b). Only one core clinical feature is present, but with ≥1 indicative biomarkers. Probable DLB should not be diagnosed on the basis of biomarkers alone. Possible: (a). Only one core clinical feature of DLB is present, with no indicative biomarker evidence, OR (b). ≥1 indicative biomarkers is present but there are no core clinical features. |
Diagnosis of probable or possible PDD |
Probable: (a) Core features: Both must be present; (b). Associated clinical features: Typical profile of cognitive deficits and the presence of at least one behavioral symptom (lack of behavioral symptoms, however, does not exclude the diagnosis); (c) None of the group III features present; (d) None of the group IV features present. Possible: (a) Core features: Both must be present (b). Associated clinical features: Atypical profile of cognitive impairment in one or more domains (e.g., fluent aphasia, or pure storage-failure type amnesia) and behavioral symptoms may or may not be present; OR (c) One or more of the group III features present, (d) None of the group IV features present |