REM sleep behavior disorder and other sleep disturbances in Alzheimer's disease, dementia with Lewy bodies and in dementia cases of uncertain classification

Objectives/Introduction: Sleep disorders are common in persons with Alzheimer´s disease (AD) and dementia with Lewy bodies (DLB). Their identification, especially of REM sleep behavior disorder (RBD), a core clinical feature for DLB diagnosis, is an important support to improve diagnostic accuracy between these two types of dementia and optimize therapeutic strategies. Methods: In this ongoing study, consecutive patients with AD, DLB or uncertain diagnosis between AD/DLB and mild-to-moderate dementia severity are screened for sleep disturbances. Recruited patients undergo two consecutive full-night video-polysomnographies (vPSG). Patients diagnosed with moderate to severe obstructive sleep apnea (OSA) after the first vPSG are treated with positive airway pressure (PAP) ventilation during the second vPSG. Results: To date, 31 patients have been screened and 13 recruited (60% men; mean age 77 ± 2 years; 46% Clinical Dementia Rating score [CDR] 1 and 54% CDR 2). At enrollment, 54% had a diagnosis of AD, 23% of DLB and 23% of AD/DLB. 69% of patients complained of poor sleep quality, while only 15% of excessive daytime sleepiness. 77% presented a high risk for OSA, 70% a clinically possible RBD and 38% restless legs syndrome. VPSG analysis confirmed OSA in 9 patients, periodic limb movements in 7 and confusional arousals in 4. 86% of OSA patients used PAP treatment for at least 5 hours during the second vPSG. RBD was confirmed in 10 patients. Based on these findings and according to current DLB diagnostic criteria, 5 patients previously diagnosed with AD and 2 patients AD/DLB were diagnosed with DLB. Moreover, CDR 2 patients presented a decrease in percentage of REM sleep and atypical REM sleep phases (predominant delta activity) as compared to CDR 1 patients (p = 0.048 and p = 0.027, respectively). Conclusions: Our preliminary findings show a high comorbidity of vPSG-confirmed RBD with other primary sleep disorders (OSA in particular) in dementia patients. Both in AD and DLB, with the progression of cognitive decline, standard REM sleep scoring becomes complex. VPSG remains the gold standard for the diagnosis of RBD and its mimics and it is a useful tool for improving dementia diagnostic accuracy.