Lewy body pathology (presence of Lewy bodies in the brain) is found in up to 50% of cases of late-onset Alzheimer’s disease, which can make it challenging for physicians to distinguish the underlying cause or causes of dementia symptoms. The diagnostic problem is compounded because Lewy bodies alone can result in another dementing illness, dementia with Lewy bodies (DLB). A new study shines new light on important clinical differences between people who have autopsy-verified Alzheimer’s disease pathology alone versus those who have both Alzheimer’s and Lewy bodies.
Researchers from the Inje University College of Medicine in Korea, in collaboration with researchers from Washington University School of Medicine and the National Alzheimer’s Coordinating Center, reviewed clinical and autopsy records of individuals followed at federally-funded Alzheimer’s Disease Research Centers in the U.S. The aim of the study was to identify whether the clinical presentation and progression differed between those with Alzheimer’s disease (AD) alone, or those who also had the presence of Lewy body pathology (AD with Lewy bodies).
“Recognizing the likely presence of Lewy bodies in a person with dementia is important, in part because some drugs used to treat certain dementia symptoms may cause serious problems in patients with Lewy bodies, stated senior author, John Morris, M.D., Director of the Knight Alzheimer Disease Research Center at Washington University School of Medicine. “It also suggests that the lesions of Alzheimer’s disease may share common mechanisms with those that result in Lewy bodies.”
The cohort included 531 individuals, with cognitive abilities ranging from no cognitive impairment to advanced dementia. All participants’ autopsies indicated they had Alzheimer’s disease. Out of a total 531 participants, 316 (59.5%) had AD only. The other 215 (40.5%) had AD combined with Lewy bodies. Having at least 1 copy of the ε4 allele of the apolipoprotein E (APOE) gene was higher for participants with AD and Lewy bodies. This allele is independently linked to both AD and DLB.
The mean age of dementia onset was younger (6.0 years) for those with both AD and Lewy bodies than for those with AD alone. While there was no statistically significant difference in disease duration, the mean age at death was 2.3 years younger for those with AD and Lewy bodies. As seen in dementia with Lewy bodies (DLB), more men than women had AD with Lewy bodies. There was no statistically significant difference in education levels.
During life, of the 316 individuals with only Alzheimer’s pathology, 21 (6.6%) had a clinical diagnosis of DLB. Those who had both Alzheimer’s and Lewy bodies at autopsy (63 or 29.3%) were 4 times more likely to be diagnosed DLB during life.
Participants with Alzheimer’s and Lewy bodies had a higher degree of neuropsychiatric symptoms, specifically delusions and hallucinations, as well as greater problems with movement. This suggests that the clinical traits of individuals with AD with Lewy bodies is probably similar to that of DLB.
This study was first published online in JAMA Neurology on May 18, 2015. Funding for this study was provided by the National Institute on Aging, Fred Simmons, Olga Mohan and the Charles F. and Joanne Knight Alzheimer’s Research Initiative of the Washington University Charles F. and Joanne Knight Alzheimer’s Disease Research Center.