Dementia with Lewy bodies: diagnosis and management

OBJECTIVE

To summarize the clinical, pathological, imaging and treatment aspects of dementia with Lewy bodies (DLB).

METHOD

Review of literature (MEDLINE).

RESULTS

DLB is the second most common form of degenerative dementia, accounting for up to 20% of cases in the elderly. It is characterized by fluctuating cognitive impairment, spontaneous parkinsonism and recurrent visual hallucinations. Consensus clinical criteria have been published and have been shown to have high specificity, but they may still lack sensitivity. Pathologically, DLB may be classified as a Lewy body (LB) disorder and/or as an alpha-synucleinopathy. It is probable that a spectrum of LB disorders exists with the clinical features reflecting the distribution and severity of pathology. Although both DLB and Alzheimer's disease (AD) show a reduction in pre-synaptic cholinergic transmission from the basal forebrain, in DLB there are also deficits in cholinergic transmission from brain stem nuclei. Post-synaptic cortical muscarinic receptors are more functionally intact in DLB suggesting potential responsiveness to cholinergic enhancement. Neuroimaging findings indicate a relative preservation of medial temporal lobe structures in DLB but similar distribution of white matter changes on MRI compared with AD. Defects in nigrostriatal dopamine pathways in DLB have been demonstrated with functional neuroimaging using ligands highlighting pre- and post-synaptic dopaminergic systems. Preliminary studies also indicate subtle differences in perfusion patterns on SPECT with a greater degree of occipital hypoperfusion in DLB compared with AD. Accurate diagnosis of DLB is clinically important as the management of psychosis and behavioural disturbances is complicated by sensitivity to neuroleptic medication. There is accumulating evidence to suggest that DLB may be particularly amenable to cholinergic enhancers. The clinical management of DLB is considered using a four step approach: making a diagnosis; identification of problem symptoms; appropriate non-pharmacological interventions; and pharmacological interventions.

CONCLUSIONS

Consensus criteria for probable DLB have high specificity-a positive clinical diagnosis is likely to be correct. Treatment choices must consider effects upon motor, cognitive and psychiatric symptoms. Non-pharmacological management is an essential first step, as is reduction or withdrawal of drugs with potential adverse effects. Neuroleptic sensitivity reactions appear less likely to occur with the newer atypical antipsychotics. Cholinesterase inhibitors have been shown in open-label studies and one placebo RCT to be well tolerated and effective in treating cognitive and psychiatric symptoms in DLB. They may become first-line treatments.