The two dementias have an overlap between one another as Lewy Body Dementia is accompanied by Alzheimer’s dementia 80 percent of the time and clinically diagnosed Alzheimer patients were found to have brain pathology associated with Lewy Body dementia at the time of autopsy 35 percent of the time. Lewy body dementia is estimated to be present in 1.3 million people in the US however because symptoms are associated with other more well known dementias, it is often misdiagnosed and unrecognized. Neurology Today (10-7-2010)
It can take several years for symptoms to surface clinically to make a diagnosis. However neuropsychological evaluation has a clear method to separate out symptoms of Alzheimer’s dementia from Lewy Body early in the disease process but not late in the disease process. Symptoms overlap is far more likely to emerge during later stages of the disease process as more of the brain becomes compromised.