Nocturnal behavioral disturbance is highly prevalent among elders with dementia and frequently leads to their instituionalization. We hypothesized that nighttime behavioral disturbacnes may be associated with three common sleep disorders: obstructive sleep apnea syndrome, periodic limb movement disorder, and restless legs syndrome (RLS). The purpose of this study was to determine in apnea-hypopnea index (AHI), oxygen saturation nadir, periodic leg movement sleep index (PLMI), possible RLS, and total sleep time predict observed nighttime behavioral symtopms in persons with dementia
The specific aims of this study are to: 1) describe the sleep and behavioral patterns of elders with CI whose caregivers report nighttime sleep and behavioral disturbance, and 2) explore the impact of obstructive sleep apnea syndrome, periodic limb movement disorder, and restless legs syndrome on nighttime sleep and behavioral disturbances in elders with CI
A sleep technician conducted two overnight attended full polysomnography (PSG) studies in the homes of the 60 participants (41 males). Within one week, a trained research assistant (RA) observed participants continuously in their homes for three nights (a total of 19 hours) for nighttime behavioral symptoms using the Cohen-Mansfield Agitation Inventory. We used these observations to calculate behavioral symptoms per hour of observation (Behavioral Disturbance Index (BDI)) during presumed wake. The RA also observed for specific RLS behaviors, such as rubbing the legs and frequent crossing of legs every five minutes. Interrater reliability of the RA's observations, done at study onset and quarterly during data collection, rangedfrom .90 - .95. One registered polysomnographic techologist, blinded to frequency of behavioral symptoms in participants, scored the overnight PSG studies. Since older adults with dementia often do not have the cognitive skills to answer the RLS diagnostic interview questions, two RLS experts independently rated each participant as possible RLS or no RLS based on the following data: 1)diagnoses and medications, 2) caffine and alcohol intake, 3) chief sleep complaint (from caregive and/or elder), 4) caregiver RLS diagnostic interview, 5) polysomnography data including AHI and PLMI, and 6) RA obersavtions of RLS signs. Correlations were used to analyze these data. TheBDI was the dependent variable in zero-order and multiple regressions. Only significant zero-order correlations with the BDI criteria were used in the multiple regressions. Square-root adjustments substantially improved BDI normality; the AHI predictor required a lof transformation.
Mean agge was 79.05 years (s.d. = 6.03) and mean Mini-Mental State Examination (MMSE) score was 20.05 (s.d. = 7.33). The most common behavioral symptom was general restlessness (43 persons). RLS, MMSE and log AHI significantly predicted BDI (R2 = .31, N=57, F[3,53]=9.40, p=.000). All three predictors were uniquely significant. The post estimation tests (omitten variables and variance inflation fator) were well within accepted levels.
Conclusions: Poissble RLS, a lower MMSE and a lower AHI were associated with objectively measured nighttime behavioral symptoms, such as wandering and general restlessness, in elders with dementia. Sensitive objective RLS diagnostic measures and effectve treatment may reduce caregiver burden and institutionalization of elders with dementia.
If the specific sleep disorders of older adults who have dementia and nighttime sleep and behavioral disturbances are identified, more informed, targeted, and effective interventions may delay or preempt the institutionalization resulting in significant cost savings to the VA and improving the quality of life of veterans with dementia and their caregivers. The findings of this research led to a R01 grant on the Validation of Measures of Restless Leg Syndrome for Elders with Memory Disorder.
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