Clinical, neuropathological and neuroimaging features of Alzheimer's disease and dementia with Lewy bodies

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are the two most common types of degenerative dementia. It has been questioned whether they are totally separate conditions, or whether they are in fact both part of a spectrum of a more general neurodegenerative disease. Fluctuating cognition and parkinsonism are key features of DLB, but atypical in AD which is characterized by progressive amnesia, aphasia, agnosia and apraxia. Neuropsychiatric disturbances also seem to be more common in DLB. The main neuropathological features of DLB are Lewy bodies, and in AD are senile plaques and neurofibrillary tangles, though some overlap has been found. A key finding of neuroimaging studies is that there is relative preservation of brain volume in DLB patients compared with AD patients, particularly of temporal lobe structures. There are also profound reductions in striatal dopamine transport in DLB, demonstrated by single photon emission computerized tomography (SPECT) imaging. Whilst there are some distinct differences between AD and DLB, further research is needed to greater define the distinctions between these two conditions.