New research shows that Alzheimer's disease and other dementing illnesses may be easily misdiagnosed in the elderly, according to early results of a study of people in Hawaii who had their brains autopsied after death. The research is being released early and will be presented as part of a plenary session at the American Academy of Neurology’s 63rd Annual Meeting in Honolulu April 9 to April 16, 2011.

"Diagnosing specific dementias in people who are very old is complex, but with the large increase in dementia cases expected within the next 10 years in the United States, it will be increasingly important to correctly recognize, diagnose, prevent and treat age-related cognitive decline," said study author Lon White, MD, MPH, with the Kuakini Medical System in Honolulu.

For the study, researchers autopsied the brains of 426 Japanese-American men who were residents of Hawaii, and who died at an average age of 87 years. Of those, 211 had been diagnosed with a dementia when they were alive, most commonly attributed to Alzheimer's disease.

The study found that about half of those diagnosed with Alzheimer's disease did not have sufficient numbers of the brain lesions characterizing that condition to support the diagnosis. Most of those in whom the diagnosis of Alzheimer's disease was not confirmed had one or a combination of other brain lesions sufficient to explain the dementia. These included microinfarcts, Lewy bodies, hippocampal sclerosis or generalized brain atrophy.

However, diagnoses of Lewy body dementia and vascular dementia were more accurate. Misdiagnoses increased with older age. They also reflected non-specific manifestations of dementia, a very high prevalence of mixed brain lesions, and the ambiguity of most neuroimaging measures.

"Larger studies are needed to confirm these findings and provide insight as to how we may more accurately diagnose and prevent Alzheimer's disease and other principal dementing disease processes in the elderly," said White.

The study was supported by the National Institute on Aging and the Department of Veterans Affairs.

This research will be presented as part of the Contemporary and Clinical Issues and Case Studies Plenary Session on Wednesday, April 13, 2011, at the 2011 American Academy of Neurology's Annual Meeting in Honolulu.