The Whitworths of Arizona, bringing science to you in everyday language.

Friday, January 30, 2015

RBD and MCI Historical Timelines

The January 11th blog was a review of the timeline for how Parkinson’s disease and Lewy body dementia went from being discovered to being recognized as a disease by a few researchers, to being recognized as a disorder where Lewy bodies were present, to being a disorder caused by Lewy bodies, to being recognized by the general public. This week is a review the other two Lewy body disorders and how they became accepted as such. Notice that these timelines start much later. Also notice that at first each “disorder” was considered a symptom of LBD or of encroaching LBD before it was named as a Lewy body disorder in its own right.

REM Sleep Behavior Disorder (RBD)

1986: Dr. Charles Schenck and associates first describes REM sleep behavior disorder in an article in SLEEP, a journal published by the Sleep Research Society and the American Academy of Sleep Medicine.

2001: RBD is identified as specific sleep disorder in the International Classification of Sleep Disorders, 1st edition (ICSD-1) which allows doctors to charge insurance companies for its treatment.

1996: RBD is named as a probable symptom of Lewy body dementia. At least 50% of the time, RBD will progress into PD, LBD or both.

2009: Researchers report that Lewy bodies are always present in autopsies of people with RBD.

Mild Cognitive Impairment-Lewy Body type (MCI-LB), also called “non-amnestic MCI.”

1988: ”Mild cognitive impairment” is first used as a descriptive term coinciding with a person’s rating on a dementia scale as preclinical or borderline. (Reisberg et al)

1995: “Mild cognitive impairment (MCI)” is first used as an independent diagnostic category not linked to a previously defined rating scale. (Petersen et al)

2004: Gathier suggests dividing MCI patients into those with amnestic MCI which tends to advance to Alzheimers, and non-amnestic MCI, which tends to advance to LBD.

2010: Ferman, et al found that autopsies of all subjects with non-amnestic MCI and RBD had Lewy bodies in the cognitive and dream management centers of the brain.

2013: Mild Neurocognitve Disorder (MNI) is listed as a specific disease in the DSM-5. The DSM-5 renamed “dementia” to “major neurocognitive disorder” and MCI to the above. What do you think of this renaming? Will it fly?) For now, be aware that the old and new terms are synonymous but expect to see the old terms much more often.

The two types of MCI (amnestic and non-amnestic MCI) have not yet been formally recognized as such although researchers and clinicians appear to accept the terms provisionally. This is understandable since at this time, the kind of dementia that will follow either type can only be guessed with a moderate to fair amount of accuracy. It isn’t a sure thing.

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