The relations among caregiver stress, "sundowning" symptoms, and cognitive decline in Alzheimer's disease.

OBJECTIVE: To investigate the relations among the initial perceived stress of Alzheimer patients' caregivers, the rate of change of perceived stress, patients' sundowning behaviors, and patients' rate of cognitive decline.

DESIGN: A longitudinal cohort study in which Alzheimer patients and their caregivers were assessed at 6-month intervals.

SETTING: Hospital out-patient clinic. Patients and caregivers lived at home.

SUBJECTS: Subjects were 35 patients (50-79 years) with Alzheimer's disease and their primary caregivers (24 males and 11 females); all caregivers were spouses.

METHODS: At time of entry into the study, caregivers indicated which of seven behaviors indicative of sundowning were exhibited by the patient. Patients were evaluated successively using the Mini-Mental State Examination, whereas caregivers completed the Perceived Stress Scale, provided an index of social support utilization, and completed the Beck Depression Inventory.

MAIN OUTCOME MEASURES: Caregivers' initial perceived stress and the rate of change of perceived stress, patients' sundowning behavior, and rate of cognitive decline.

RESULTS: The pattern of correlations indicated that both rate of cognitive decline and initial sundowning behavior were significantly correlated with initial perceived caregiver stress. The average rate of increase of caregivers' perceived stress was positively correlated with the initial incidence of sundowning behaviors, even when controlling for the effects of caregiver depression and social support utilization.

CONCLUSION: Sundowning behavior of Alzheimer patients is associated with an increased rate of change of caregivers' perceived stress. This association may be specific to sundowning behavior because there was no relation between the rate of change of perceived stress and morning agitation. The findings suggest that future caregiver intervention programs could profitably focus on sundowning behavior rather than general agitation.