Clinical differentiation of Lewy body disease (LBD) from Alzheimer disease (AD) is still problematic. Many persons with LBD lack the cardinal features of visual hallucinations, fluctuations in cognition, and mild Parkinsonism proposed by McKeith et al. (2005). Some studies suggest that history or presence of depression may help distinguish LBD from AD, but this is confounded because many clinically diagnosed LBD patients have significant co-morbid AD pathology and vice versa (Ranginwala et al., 2008). We aimed to clarify whether history or symptoms of depression differentiate LBD from AD, in autopsy-confirmed patients, excluding patients with mixed AD and LBD pathology.