sailor girlDementia with Lewy Bodies: Trying to Define a Disease

Although AD and vascular dementias have been regarded as the major dementias of late life, increased research in neurodegeneration has resulted in the identification of a dementia symptom complex characterized by rapid progression of dementia, visual hallucinations, Parkinsonism, and fluctuations in dementia severity, alertness, and attention, and it is referred to as Lewy Body Dementia.

Why is this important for the general neurologist to know? First, the above findings suggest that the second most common neurodegenerative dementia seen in a neurologist's clinical practice is DLB in some form. Second, knowledge of this syndrome can enable proper diagnosis of a dementia case with puzzling symptoms or course, and DLB is not an uncommon dementia. The symptoms, evolution, rate of cognitive change, response to therapy, and genetic risks may be different in DLB than in other neurodegenerative dementias. Some commonly used medications, such as neuroleptics, may be contraindicated in these cases. As new medications emerge for AD, the neurologist will need to know whether and how they should be given to DLB patients.

Materials and Methods

Recent neuropathologic studies found Lewy bodies (LB) in the brainstem and cortex of 15%­25% of all elderly demented patients (the largest pathologic subgroup after pure Alzheimer's disease [AD).

Formal testing is essential for establishing diagnosis, and detailed testing may reveal a deficit profile that identifies and distinguishes DLB.

Core requirements are (1) fluctuating cognition with pronounced variation in attention and alertness, (2) recurrent and detailed visual hallucinations, and (3) spontaneous motor features of parkinsonism. The presence of one core feature is required for diagnosis of possible DLB, and the presence of two core features is required for probable diagnosis.

Clinical features supportive of DLB diagnosis are:

(1) repeated falls, (2) syncope, (3) transient loss of consciousness, (4), systematized delusions, and (5) hallucinations. The identification of stroke disease, physical illness, or other brain disorder make DLB diagnosis less likely, although DLB should not be excluded simply on this basis.

The essential pathologic feature for diagnosis of DLB is the presence of Lewy bodies. Associated but not essential pathologic features are (1) Lewy-related neurites, (2) all morphologic types of plaques, (3) neurofibrillary tangles, (4) regional neuronal loss, especially brainstem (substantia nigra and locus coeruleus) and nucleus basalis of Meynert, (5) microvacuolation (spongiform change) and synapse loss, and (6) neurochemical abnormalities and neurotransmitter deficits.

What are the relevant clinical criteria for DLB that neurologists should know?

They consist of one required symptom (central feature), the presence of one (for possible DLB) or two (for probable DLB) of three clinical (core) features, and a list of six other symptoms that are supportive of the diagnosis (Table 1). The patient must have dementia meeting DSM-IV criteria. The National Institute of Neurological Communicative Disorders and Stroke-Alzeimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria [1] may be useful, but since early in DLB the dementia may not necessarily include loss of recent memory, patients could meet criteria for DLB without necessarily meeting the NINCDS-ADRDA criteria. It is for this reason that in cases where DLB is suspected, more detailed neuropsychologic testing should be done. Even in patients who do not display memory loss early, recent memory function eventually becomes significantly impaired.

Clinical Criteria for the Diagnosis of Dementia with Lewy Bodies (DLB): ---> Central feature
Dementia: Required for DLB diagnosis; must interfere with social and or occupational function----> Core features

1. Variation in cognition, attention, or alertness (not due to delirium or medical illness)
2. Detailed, recurrent well-formed visual hallucinations
3. Repeated falls, syncope, transient loss of consciousness,
4. Delusions or hallucinations

Comment: One of the three required for possible DLB;

Guidelines for the Clinical and Pathologic Diagnosis of Dementia with Lewy Bodies (DLB):
Article by I. G. McKeith, M.D.,* D. Galasko, M.D., K. Kosaka, M.D., E. K. Perry, D.Sc., D. W. Dickson, M.D., L. A. Hansen, M.D., D. P. Salmon, Ph.D., J. Lowe, D.M., S. S. Mirra, M.D., E. J. Byrne, M.R.C. Psych., G. Lennox, M.D., N. P. Quinn, M.D., J. A. Edwardson, Ph.D., P. G. Ince, M.D., C. Bergeron, M.D., A. Burns, M.D., B. L. Miller, M.D., S. Lovestone, M.R.C. Psych., D. Collerton, M.Sc., E. N. H. Jansen, M.D., C. Ballard, M.D., R. A. I. de Vos, M.D., G. K. Wilcock, D.M., K. A. Jellinger, M.D., and R. H. Perry, D.Sc., for the Consortium on Dementia with Lewy Bodies; Neurology 1996;47:1113­1124

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