Prodromal dementia with Lewy bodies.
Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementing disorder after Alzheimer's disease (AD), but there is limited information regarding the prodromal DLB state compared with that of AD. Parkinson's disease (PD) and DLB share common prodromal symptoms with Lewy body disease (LBD), allowing us to use a common strategy for identifying the individuals with an underlying pathophysiology of LBD. Dysautonomia, olfactory dysfunction, rapid eye movement sleep behavior disorder (RBD) and psychiatric symptoms antedate the onset of dementia by years or even decades in patients with DLB. Although RBD is the most potentially accurate prodromal predictor of DLB, disease progression before the onset of dementia could differ between the prodromal DLB state with and without RBD. Experts who specialize in idiopathic RBD and DLB might need communication in order to clarify the clinical relevance of RBD with the disease progression of DLB. The presence of prodromal LBD symptoms or findings of occipital hypoperfusion/hypometabolism helps us to predict the possible pathophysiological process of LBD in non-demented patients. This approach might provide the opportunity for additional neuroimaging, including cardiac (123) I-metaiodobenzylguanidine scintigraphy and dopamine transporter imaging. Although limited radiological findings in patients with prodromal DLB states have been reported, there is now a need for larger clinical multisite studies with pathological verification. The long prodromal phase of DLB provides a critical opportunity for potential intervention with disease-modifying therapy, but only if we are able to clearly identify the diversity in the clinical courses of DLB. In the present article, we reviewed the limited literature regarding the clinical profiles of prodromal DLB.