Lewy bodies dementia
is one of the most common types of dementia. The central feature of this condition is progressive cognitive decline, combined with three additional defining features: (1) fluctuations in alertness and attention, such as frequent drowsiness, lethargy, lengthy periods of time spent staring into space, or disorganized speech; (2) recurrent visual hallucinations, and (3) parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement. Although the exact cause of this condition is unknown, symptoms result from the build-up of abnormal structures, called Lewy bodies, inside the brain. This condition usually occurs sporadically, in people with no known family history of the disease. However, rare familial cases have been reported. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.