For a look at some of the data behind Dr. Boeve’s presentation, as well a list of researchers involved in this analysis, Download MCI-DLB AAN09 PosterFinal to view the poster he and his colleagues presented at the American Academy of Neurology Annual Meeting in Seattle, Washington, April 2009. You’ll need Adobe Reader to view this file.
Pathologists sometimes find Lewy bodies in the brains of people who had Mild Cognitive Impairment (more on this in a future report). But can a doctor make a diagnosis when the patient is still living?
So far, no blood, spinal fluid, imaging or other test can be used to diagnose Lewy body disease, although a more “normal” looking MRI and lack of amyloid on a PiB PET scan may indicate a patient is more likely to have Lewy body disease rather than Alzheimer’s or vascular dementia [see discussion of PiB in the Diagnosis report from the Symposium]. But a person’s medical history and symptoms may support a tentative diagnosis of Lewy body disease in someone with Mild Cognitive Impairment (MCI). At the Mild Cognitive Impairment Symposium, Brad Boeve, Professor of Neurology at the Mayo Clinic in Rochester, Minnesota, presented an analysis of the symptoms of MCI patients at Mayo who were found at autopsy to have had Lewy body disease.
In his experience, people with any type of MCI can develop Lewy body dementia. But it’s often patients with Non-Amnestic MCI (specifically those who have problems with attention, planning and organizing, and visuospatial functions) who are likely to have early Lewy body disease. These patients tend to perform well on language tests, but their performance on memory tests is highly variable [fluctuating cognition is a hallmark of Lewy body disease].
Another sign someone might have Lewy body disease is Rapid Eye Movement Sleep Behavior Disorder (RBD). In RBD, people (usually males age 20-50) act out their dreams. People with RBD may punch and kick in their sleep, and can sometimes hurt themselves or a spouse.
RBD may develop years or even decades earlier than any problems with memory and thinking. Dr. Boeve believes this indicates the alpha-synuclein pathology involved in Lewy body disease is already present in the brainstem, or lower part of the brain, where REM sleep is controlled.
RBD is also associated with other neurodegenerative diseases, but the association is strongest with those diseases involving alpha-synuclein pathology (including Lewy body disease and multiple system atrophy). In a group of 45 Mayo Clinic patients with RBD, only two were found to have non-alpha-synuclein pathology diseases. All Mayo patients studied who had both RBD and MCI had Lewy body disease at autopsy.
Dr. Boeve and his colleagues have developed a short questionnaire for spouses of patients to fill out, and have found it to be 97 percent accurate in detecting REM Sleep Behavior Disorder.
Other symptoms suggestive of early Lewy body disease are daytime sleepiness, constipation, loss of sense of smell and a large decrease in blood pressure when a person stands up.
What does it matter whether someone with MCI has a Lewy body disorder instead of another neurodegenerative disease, vascular dementia or other condition? “Identifying Lewy body disease as the underlying cause of mild cognitive impairment is important for several reasons,” explained Dr. Boeve in an email after the conference. “The symptoms that often evolve as the illness progresses are quite different from Alzheimer’s disease, and it is important to plan ahead in case some problems such as hallucinations or delusions occur. Plus, some patients experience significant improvement in their cognitive symptoms with acetylcholinesterase inhibitors. On the other hand, conventional neuroleptics such as haloperidol should never be used. Eventually when therapies that positively influence Lewy body disease pathophysiology are available, it will be critical to use them as early in the illness as possible, and MCI patients who have RBD would be particularly important to diagnose and treat.”
Note: “Identifying Mild Cognitive Impairment,” one of the supplemental films in HBO’s Alzheimer’s Project, features Dr. Ron Petersen interviewing a Mayo Clinic patient with both MCI and REM Sleep Behavior Disorder.