Chris MacKnight, MD, MSc, FRCPC, Assistant Professor, Division of Geriatric Medicine, Dalhousie University, Halifax, NS.
Lewy body disease is one of the many conditions causing dementia. As it is relatively common, and has an effective management distinct from that of Alzheimer disease,1 all physicians who see older adults should have some familiarity with Lewy body disease.
Lewy body disease is underdiagnosed.2 It should be suspected in an older adult who presents with cognitive impairment (even if quite mild) in addition to hallucinations or parkinsonism. Clinical criteria are presented in Table 1.3,4 The criteria of fluctuation have proven difficult to apply at the bedside, but clinical tools are now available.5 The parkinsonism is often mild and subtle, and is more often rigidity than tremor. An important feature is neuroleptic sensitivity. Up to 80% of these patients can, even with low doses, develop reactions to neuroleptics or atypical agents, which are often severe.6 Extrapyramidal symptoms and cognitive decline are the most common manifestations. The decline can be permanent, and neuroleptic malignant syndrome can occur. This likelihood of reaction to neuroleptics is one of the chief reasons to be familiar with the disorder and to have a low threshold to at least suspect its presence.
It can sometimes be difficult to distinguish Lewy body disease from Alzheimer disease, Parkinson's disease or delirium.