Lewy body dementias include dementia with Lewy body disease (DLB) and Parkinson’s disease with dementia (PDD). Common symptoms include problems with movement, visual hallucinations, and fluctuations in thinking skills or attention.
Some patients with Parkinson’s disease (PD) experience no or only subtle cognitive decline, and their primary limitation is their motor disorder. However, other patients with Parkinson’s disease develop dementia as a consequence of the disease. When dementia develops after an established motor disorder, we call the disease Parkinson’s disease with dementia (PDD). In contrast, when dementia develops prior to or concurrently with the motor disorder, we call the disease dementia with Lewy bodies (DLB).
Although the initial symptom sequence differs between PDD and DLB, as the disorders progress, the symptoms and underlying brain changes are much more similar than different. As such, many researchers and clinicians view PDD and DLB as part of a continuum of disease rather than as distinct entities.