Dementia with Lewy bodies is a relatively common cause of dementia. Much has been learned about this disorder, yet much remains to be elucidated, especially in regard to early clinical diagnosis. To clarify the future research agenda in this area, the authors critically appraise the literature on cognitive and behavioral changes in DLB and provide a brief overview of the history of DLB, the main pathological changes, and the findings related to extrapyramidal symptoms and treatment issues. Twenty-one studies on cognition and 47 on behavioral changes in DLB are reviewed. Impairments of working memory and visuospatial functions, visual hallucinations, and depression (or symptoms of depression such as apathy and anxiety) have been identified as early indicators of DLB. However, longitudinal and cross-sectional data are lacking, particularly for different aspects of working memory, visual perception, and non-psychotic behavioral symptoms.