Summary Question of the study
Besides their cognitive disorders, patients with dementia commonly present with a sleep-wake rhythm disturbance, sleep fragmentation, and sleep efficiency reduction. To date, very few studies have comparatively evaluated sleep disorders in different classes of dementia. The objective of our examination was to detect specific and unspecific polysomnographic changes in different dementia types.
Patients and methods
To date, 21 patients with a low to moderate grade of dementia have been examined. All patients received a thorough examination including routine neurologic and psychiatric examination, blood chemistry, CT/MRI, neuropsychologic evaluation, EEG and, when necessary, lumbar puncture, and Doppler/duplex. According to international standard criteria, 14 patients were classified with Alzheimer's disease (DAT), five with frontotemporal dementia (FTD), and two with dementia with Lewy bodies (DLB). Patients with vascular dementia were not included in our analysis due the heterogeneity of this particular type of dementia. After an adaptation night, a polysomnography was performed on all patients, who were free, of psychotropic medication before the beginning of therapy with antidementive medication.
Results
In all patients, a marked sleep continuity disruption was observed, which in most cases was not perceived by the patients. Moreover, in patients with DAT, a more accentuated REM sleep reduction in comparison to patients with FTD, was found. In addtion,. we detected a high amount of sleep-related breathing disorders (SRBD) and periodic leg movements with arousals (PLMS), predominantly in patients with DAT.
Conclusion
The prevalence of sleep disorders in patients with primary dementias is clearly higher than previously suspected. Sleep disturbances due to alteration of sleep architecture and REM sleep and due to additional factors such as SRBD and PLMS may be related to the deterioration of cognitive performance and thus can exert an important role in the expression and course of dementia.