Sleep disorder may be one of the earliest signs of neurodegenerative disorder, including early Alzheimer's disease (AD). We know for example, that REM Behavior Disorder (RBD) may precede a dementing disorder by several years. RBD involves the acting out of dreams while still asleep. The dreamer may be utterly convinced that he and his bed partner are under attack from a violent intruder and thus the dreamer may kick, fight and literally run-off while still asleep. If you or someone you know is experiencing dreams like these it may be worth contacting a sleep specialist for a check-up to rule out a disease process.
We know that mild cognitive disorder often precedes a full blown dementing process for some years before onset of that dementing illness. If significant sleep disturbance could be accurately and easily identified in individuals with mild cognitive impairment (MCI) it may be possible to slow conversion to AD and other dementias by treating the sleep disorder. The most sensitive sign of sleep disorder may sometimes be dreams--or that is bizarre or disturbing dreams.
Clinically significant sleep (and possibly dream) disturbances are indeed present in 14% to 59% of persons with mild cognitive impairment (MCI) (Beaulieu-Bonneau and Hudon, 2009), depending on how sleep disturbance is measured. In addition, sleep disturbances in MCI appear to be significantly correlated with various types of cognitive impairment in the two major subtypes of MCI: amnestic (aMCI) and non-amnestic (naMCI) (Beaulieu-Bonneau and Hudon, 2009). Unfortunately, these data are based on only a handful of studies (N=20 studies), only three of which employed objective measures of sleep quality. None of these studies looked at dreams of MCI patients either.