The clinical features of dementia with Lewy bodies (DLB) during wakefulness are well known. Other than REM sleep behavior disorder (RBD), only limited data exists on other sleep disturbances and disorders in DLB. We sought to characterize the polysomnographic (PSG) findings in a series of DLB patients with sleep-related complaints.
Retrospective study of patients with DLB who underwent clinical PSG at Mayo Clinic Rochester or Mayo Clinic Jacksonville over an almost 11 year span for evaluation of dream enactment behavior, excessive nocturnal movements, sleep apnea, hypersomnolence, or insomnia. The following variables were analyzed: respiratory disturbance index (RDI) in disordered breathing events/hour, periodic limb movement arousal index (PLMAI), arousals for no apparent reason (AFNAR), total arousal index (TAI), presence of REM sleep without atonia (RSWA), and percent sleep efficiency (SE).
Data on 78 patients (71M, 7F) were analyzed. The mean age was 71 ± 8 years. Seventy-five (96%) patients had histories of recurrent dream enactment during sleep with 83% showing confirmation of RSWA +/- dream enactment during PSG. Mean RDI = 11.9 ± 5.8, PLMAI = 5.9 ± 8.5, AFNARI = 10.7 ± 12.0, and TAI = 26.6 ± 17.4. SE was <80% in 72% of the sample, <70% in 49%, and <60% in 24%. In patients who did not show evidence of significant disordered breathing (23 with RDI<5), 62% of arousals were AFNARs. In those patients who had significant disordered breathing (55 with RDI ≥ 5), 36% of arousals were AFNARs. Six patients underwent evaluations with PSG plus MSLT. Two patients had mean initial sleep latencies less than five minutes, and both had RDI<5. No patient had any sleep onset rapid eye movement periods. Nineteen patients have undergone neuropathologic examination, and 18 have had limbic- or neocortical-predominant Lewy body pathology. One had progressive supranuclear palsy, but no REM sleep was recorded in prior PSG.
In patients with DLB and sleep-related complaints, several sleep disturbances in addition to RBD are frequently present. In this sample, about three quarters had a significant number of arousals not accounted for by a movement or breathing disturbance, and the primary sleep disorders do not appear to entirely account for the poor sleep efficiency in DLB, especially in those without a significant breathing disorder. Further studies are warranted to better understand the relationship between disturbed sleep, arousal and DLB; such characterization may provide insights into potential avenues of treatment of symptoms which could impact quality of life.