Can a Pattern of Sleep Disturbance Predict the Onset of Alzheimer's Disease?

The current issue of Alzheimer's and Dementia; the Journal of the Alzheimer's Association, carried an interesting article about a study of disturbed sleep preceding the onset of the AD disease pathology.  The article was "Alteration in sleep architecture and electroencephalogram as an early sign of Alzheimer's disease preceding the disease pathology and cognitive decline."

The study began by noting that there is an established correlation between disturbed sleep and AD.  It also recalled earlier research the investigators had conducted that found a relationship between sleep and AD in humans.  Apparently the studies focused on people in the later stages of AD.  What has not been established is whether sleep disturbance could be a feature of the early stages of AD.  Also, it was not clear how valuable electroencephalograms (EEGs) may be in studying sleep disturbances in people who have or may develop AD.

This study relied on EEG studies of mice.  (In the conclusions the authors discussed the need for future studies with human subjects.)  Mice have been used for many AD studies, because the genes of some mice have been edited to promote the development of AD.  Findings from studies in mice must, of course, be confirmed in similar studies in humans.  Sometimes findings can be confirmed, but other times there is doubt regarding how valid an analog mice are for humans in these cases.

What did they find this time?  Young mice that were genetically predisposed to develop AD but which had not begun to develop amyloid plaques displayed a different sleep "architecture."  In other words, disturbed sleep preceded the development of AD pathology -- at least the AD pathology we know how to observe.

The authors discussed the need to perform similar studies on humans.  But they also noted that this will be very difficult.  The main challenge will be finding and obtaining the cooperation of a large population of presymptomatic elderly people with AD as well as people with only the earliest symptoms.  Conducting large numbers of EEGs is difficult and time-consuming.

We have discussed before the imperative for developing diagnostic tools to identify presymptomatic AD.  While a lot of people want to know whether they are developing AD (while a lot don't...), an equally important need for such tools is to identify large numbers of potential human research subjects who have begun to develop AD but have not advanced to MCI.  These are people who, in the past, would not have known they were developing AD.

The researchers believe that further study of the relationship between sleep and the development of AD may shed important light on AD pathology and progression.