Subtypes of sleep problems in patients with Alzheimer disease.

OBJECTIVE: Sleep disturbances are common in patients with Alzheimer disease (AD) and can contribute to cognitive dysfunction and a negative impact on patients' and caregivers' quality of life. The purpose of this study was to evaluate whether subtypes of sleep disturbance could be identified in patients with AD and to assess the relation of these subtypes to patient characteristics and caregiver mood. METHODS: As part of routine clinical assessment, primary caregivers of 344 patients with AD completed a questionnaire that included five items about the patients' sleep. Patients' cognitive and functional status and their mood were assessed as was caregivers' mood. Latent class analysis was used to define subgroups of patients based on their sleep patterns. After identification of groups of sleep disturbance, the relation of group membership to patient and caregiver characteristics was also evaluated. RESULTS: Analyses revealed groups with moderate and severe sleep problems as well as a group without problems. Patients with more severe sleep disturbance were older, less well educated, and had poorer cognitive and functional status. Caregiver and patient depression was related to membership in the severe group, suggesting that both may contribute to caregivers' ratings of more severe sleep disturbance, whereas only patient depression was related to membership in the moderate group. CONCLUSION: Sleep problems in patients with AD are related to poorer cognitive and functional status and patient and caregiver depression. Caregiver depression was most closely related to more severe patient sleep disturbance.

Caregiver reports of sleep problems in non-Hispanic white, Hispanic, and African American patients with Alzheimer dementia.

STUDY OBJECTIVES: Sleep problems are common in persons with dementing illnesses and among the most stressful patient behaviors for caregivers. Although studies have shown differences in sleep across ethnic groups, little information is available on ethnic differences among persons with dementia. The purpose of this study was to investigate possible ethnic differences in sleep problems among patients with Alzheimer dementia. METHOD: Caregiver reports of 5 sleep- or circadian rhythm-related behavioral problems (behavior disturbance worse in the evening, difficulties falling asleep, frequent awakenings, early awakenings, and excessive daytime sleep) were evaluated in 395 patients who had received a diagnosis of Alzheimer disease after diagnostic evaluation. The average cognitive score of the groups suggested that they could be characterized as having moderately severe impairment. The frequency of sleep problems was then evaluated across subgroups defined by self-reported ethnicity (African American, Hispanic, and non-Hispanic white). As patient and caregiver characteristics may affect caregivers' reports of patients' behaviors, mixed effects regression models were used to adjust for patient and caregiver variables that might affect caregiver reports. RESULTS: Analyses revealed ethnic differences in sleep or circadian rhythm disturbances. African American and Hispanic patients were reported to have more severe sleep disturbances than non-Hispanic whites. After correction for patient and caregiver variables that might have affected caregiver reports, differences between African Americans and others remained. CONCLUSIONS: Sleep problems in patients with dementing illnesses are reported by caregivers with differing frequencies across groups of African Americans, Hispanics, and non-Hispanic whites. Clinicians should be aware of these differences in assessing sleep disturbance in patients with dementia as well as the potential effects of patient and caregiver variables on reports of these problems.

A three-factor model of cognition in Alzheimer disease.

OBJECTIVE: To use principal factors analysis to model cognition in Alzheimer disease. BACKGROUND: Earlier studies have used factor analysis to examine the effects on Alzheimer disease cognition of either heterogeneity in premorbid cognition or heterogeneity in the disease process itself. In the current study, both sources of heterogeneity were incorporated within a single model. METHODS: Two hundred sixty-one patients with probable Alzheimer disease (92 White Non-Hispanic, 148 Hispanic, and 21 African-American) were tested with the Mini-Mental Status Examination, the Assessment of Cognitive Abilities in Dementia, and the Short Portable Mental Status Examination. RESULTS: Three factors were obtained: one with loadings for memory and orientation, a second with loadings for language and praxis, and a third with loadings for executive functions. Factors 1 and 2 declined over 1.82 years (p = 0.0002, p = 0.0001); Factor 3 scores remained invariant over this period (p = 0.16). Furthermore, only Factor 3 scores correlated with either education (p = 0.0001) or ethnicity (p = 0.0001). CONCLUSIONS: A possible interpretation is that Factors 1 and 2 may reflect two components of the Alzheimer disease process while Factor 3 may provide an estimate of premorbid cognition. A potential practical application of the analysis is that it may provide a measure of Alzheimer disease decline that is free from correlation with education or ethnicity.