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 at the same time as the motor disorder, we call the disease dementia with Lewy body disease (DLB).
Although the initial sequence of symptoms differs in PDD and DLB, as the disorders progress, the symptoms and the underlying brain changes are much more similar than they are different. As such, many researchers and clinicians think of PDD and DLB as being on a continuum of a similar disease process rather than as two distinct entities.