Alzheimer’s disease severity and its association with patient and caregiver quality of life in Japan: results of a community-based survey

BACKGROUND: Alzheimer’s disease (AD) dementia, a progressive neurodegenerative disease, exerts significant burden upon patients, caregivers, and healthcare systems globally. The current study investigated the associations between AD dementia patient disease severity and health-related quality of life (HRQoL) of both patients (proxy report) and their caregivers living in Japan, as well as caregiving-related comorbidities such as depression. METHODS: This cross-sectional study used self-reported data from caregivers of people diagnosed with AD dementia by a healthcare provider in Japan. Caregivers were identified via online panels and invited to participate in an online survey between 2014 and 2015. Caregivers completed survey items for themselves, in addition to providing proxy measures for patients with AD dementia for whom they were caring. Patient and caregiver HRQoL was measured using the EuroQoL 5-Dimension (EQ-5D). Additional outcomes for caregivers of AD dementia patients included the Patient Health Questionnaire (PHQ-9) of depressive symptomology, as well as comorbidities experienced since initiating caregiving for their AD dementia patients. These outcomes were examined as a function of AD dementia severity, as measured by long-term care insurance (LTCI) categories. Bivariate analyses between LTCI and outcomes were conducted using independent t-tests and chi-square tests. Multivariable analyses, controlling for potential confounders, were conducted using generalized linear models (GLMs) specifying a normal distribution. RESULTS: Across 300 caregiver respondents, multivariable results revealed that increasing AD dementia severity was significantly associated with poorer patient and caregiver EQ-5D scores and a high proportion of caregivers (30.0%) reported PHQ-9 scores indicative of major depressive disorder (MDD). The most frequent comorbidities experienced after becoming caregivers of AD dementia patients included hypertension (12.7%) and insomnia (11.0%). Depression and other comorbidities did not differ significantly by patient severity. CONCLUSIONS: The current study provides unique insight into the specific degree of incremental burden associated with increasing AD dementia severity among patients and caregivers alike. Importantly, greater disease severity was associated with poorer quality of life among both patients and caregivers. These results suggest that earlier detection and treatment of AD dementia may provide an opportunity to reduce the burden of disease for patients, caregivers, and society at large.