Dementia with Lewy bodies is a progressive disease that causes hallucinations, decline in mental abilities, rigid muscles, slow movement and tremors.
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With symptoms similar to Alzheimer’s disease and Parkinson’s disease, a correct diagnosis of Lewy Body dementia can be difficult.
People who had no shrinkage in the hippocampus were 5.8 times more likely to develop probable dementia with Lewy bodies than those who had hippocampal atrophy.
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A study in the online issue of Neurology, a medical journal of the American Academy of Neurology,
shows that a lack of shrinkage in the area of the brain called the hippocampus may be a sign that people with thinking and memory problems may develop dementia with Lewy bodies rather than Alzheimer’s disease.
Atrophy of the hippocampus, the area of the brain responsible for thinking and memory, is an early sign of Alzheimer’s disease.
“Identifying people with mild cognitive impairment at risk for dementia with Lewy bodies is critical for early interventions,” says the study’s lead author Kejal Kantarci, M.D., a Mayo Clinic radiologist. “Early diagnosis helps target appropriate treatments, including what medications not to give. For example, as many as 50 percent of people with Lewy body disease have severe reactions to antipsychotic drugs.”
Lewy bodies are protein deposits that develop in nerve cells in regions of the brain involved in thinking, memory and movement.
In the study, 160 people with mild cognitive impairment had brain MRI scans to measure hippocampus size.
They also had yearly tests for an average of two years.
- During that time, 61 people, or 38 percent, developed Alzheimer’s disease, and 20 people, or 13 percent, progressed to probable dementia with Lewy bodies.
- Because Lewy body disease can be diagnosed only by an autopsy after death, it is called probable dementia with Lewy bodies.
The people who had no shrinkage in the hippocampus were 5.8 times more likely to develop probable dementia with Lewy bodies than those who had hippocampal atrophy.
Seventeen of 20, or 85 percent, of people who developed dementia with Lewy bodies had a normal hippocampus volume; whereas, 37 of the 61, or 61 percent, of people who developed Alzheimer’s disease had hippocampus atrophy.
The relationship of hippocampus volume and disease was stronger among people without memory issues. Dementia with Lewy bodies does not always affect memory.
Affected thinking skills usually include attention, problem-solving and interpreting visual information.
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Lewy body dementia (LBD) is an umbrella term for a form of dementia that has three common presentations.
- Some individuals will start out with a memory or cognitive disorder that may resemble Alzheimer’s disease, but over time two or more distinctive features become apparent leading to the diagnosis of ‘dementia with Lewy bodies’ (DLB).
Symptoms that differentiate it from Alzheimer’s include unpredictable levels of cognitive ability, attention or alertness, changes in walking or movement, visual hallucinations, a sleep disorder called REM sleep behavior disorder, in which people physically act out their dreams, and severe sensitivity to medications for hallucinations.
In some cases, the sleep disorder can precede the dementia and other symptoms of LBD by decades.
- Others will start out with a movement disorder leading to the diagnosis of Parkinson's disease and later develop dementia and other symptoms common in DLB.
- Lastly, a small group will first present with neuropsychiatric symptoms, which can include hallucinations, behavioral problems, and difficulty with complex mental activities, leading to an initial diagnosis of DLB.
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The study was supported by the National Institutes of Health, the Mangurian Foundation, Robert H. and Clarice Smith and the Abigail Van Buren Alzheimer’s Disease Research Program.
In addition to Dr. Kantarci, Mayo Clinic study co-authors are:
Tanis Ferman, Ph.D.
Bradley Boeve, M.D.
Glenn Smith, Ph.D.
Walter Kremers, Ph.D.
David Knopman, M.D.
Clifford Jack Jr., M.D.
Ronald Petersen, M.D., Ph.D.
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