The article summarizing this research is entitled “Effect of cognitive fluctuation on neuropsychological performance in aging and dementia” (Neurology 2010;74:210-217).
Published in the journal Neurology (from the American Academy of Neurology), it was authored by Adriana Escandon, Noor Al-Hammadi, and James E. Galvin, who, at the time of the study were all associated with the Alzheimer Disease Research Center at Washington University School of Medicine in St. Louis, Missouri, U.S.A.
Changes in attentiveness and cognition (such as, staring off into space, periods of sleepiness, times when your train of thought is temporarily lost and then regained) are apparent in Lewy body dementia patients.
Lewy body dementia (or dementia with Lewy bodies [DLB]) causes clumps of proteins known as Lewy bodies (alpha-synuclein and ubiquitin proteins) to form in neurons in the brain.
It causes wide fluctuations in cognition in people affected by the disease, along with hallucinations and rapid eye movement behavior sleep disorder.
Lewy body dementia is thought by the medical profession to be the second most common form of dementia. Alzheimer’s disease is the most common form of dementia.
Because the relationship of cognitive fluctuations in people with or without visible signs of Alzheimer’s disease was unknown before this study, the researchers decided to investigate its affect.
Page two talks about the specifics of the study.
The Missouri researchers studied 511 subjects between the ages of about 70 and 86 years. Their educational levels spanned between about 12 and 18 years.
They were given standard tests involving thinking and memory recall, along with several neuropsychological tests.
And, they were assessed with the numerical rating system (from CDR = 0 to 3) called Clinical Dementia Rating (CDR).
It determines the presence and severity of dementia with respect to performance in the general areas of memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care.
A rating of 0 equals "no symptoms" of dementia, while 0.5 equals "very mild," 1 equals "mild," 2 equals "moderate," and 3 equals "severe."
The subjects were also interviewed, along with a family member, with respect to regular sleepiness, drowsiness, or lethargy during the day (when sufficient sleep was recorded during the previous night).
Family members and the subjects were also asked if the subjects had periods of "... disorganized or illogical thinking, or instances of staring into space.” [Abstract]
Page three discusses the results and conclusion of the study.
The researchers found that three or four ‘individual symptoms’ with respect to cognitive fluctuations resulted in a person having 4.6 times more chance of having dementia that others without this number of individual cognitive-fluctuation symptoms.
In addition, the researchers diagnosed 216 of the participants with “very mild” to “mild” dementia. Of that number, 25 had mental lapses—or approximately 11.6%.
The researchers diagnosed 295 of the subjects to not have dementia. Of that number, only two had mental lapses—or only about 0.7%.
Within their abstract, the researchers stated, "Participants who presented with disorganized, illogical thinking were 7.8 times more likely to be rated CDR > 0. The risk of being rated CDR = 0.5 among those with fluctuations was 13.4 times higher than among those without fluctuations. The risk of being rated CDR = 1 increased 34-fold among participants with fluctuations."
The researchers stated in their abstract, “Compared with participants without fluctuations, the presence of cognitive fluctuations corresponds to a decrease in performance across individual neuropsychological tests as well as composite scores.”
U.S. neurologist James Galvin, one of the authors of the study, stated, "If you have these lapses, they don't by themselves mean that you have Alzheimer's. Such lapses do occur in healthy older adults. But our results suggest that they are something your doctor needs to consider if he or she is evaluating you for problems with thinking and memory."
Galvin adds, "We have some ideas about why the biology of dementia with Lewy bodies causes these mental lapses, but nothing comparable for Alzheimer's. It's possible that some of the patients who were diagnosed with Alzheimer's disease in this study will go on to develop dementia with Lewy bodies, but at the time of the study, they weren't showing any of the Lewy body dementia's core features." [EurekAlert (1-18-2010): “Staring, sleepiness, other mental lapses more likely in patients with Alzheimer's”]
The researchers concluded, “Cognitive fluctuations occur in Alzheimer disease and, when present, significantly affect both clinical rating of dementia severity and neuropsychological performance. Assessment of fluctuations should be considered in the evaluation of patients for cognitive disorders.” [Abstract]