A study involving 511 older adults (average age 78) has found that 11.6% of those with very mild or mild Alzheimer’s (43% of the participants) had mental lapses, compared to only 2 of the 295 without Alzheimer’s. Those with mental lapses also tended to have more severe Alzheimer’s. Although mental lapses are characteristic of dementia with Lewy bodies, this is the first study to look at them in connection with Alzheimer’s. Having mental lapses was defined as having three or four of the following symptoms:
- Feeling drowsy or lethargic all the time or several times per day despite getting enough sleep the night before
- Sleeping two or more hours before 7 p.m.
- Having times when the person's flow of ideas seems disorganized, unclear, or not logical
- Staring into space for long periods
 . Effect of cognitive fluctuation on neuropsychological performance in aging and dementia. Neurology [Internet]. 2010 ;74(3):210 - 217. Available from: http://www.neurology.org/cgi/content/abstract/74/3/210