Do changes in specific cognitive functions predict changes in health-related quality of life in people with Alzheimer's disease?
Currently available pharmacological treatments in Alzheimer's disease (AD) have been associated with modest benefits to cognition, but the impact on health-related quality of life (HRQoL) is less well established. Our aim was to determine if decline of specific cognitive functions commonly associated with AD predict which patients maintain or experience a deterioration of their HRQoL over 18 months.
We completed an 18-month longitudinal study of 47 community-dwelling older adults diagnosed with probable AD of mild or moderate severity (NINCDS-ADRD criteria) and their family carers. The primary outcomes of interest were 18-month change in self-reported and carer-reported ratings on the quality of life-AD (QoL-AD). The main explanatory variables were 18-month change in specific cognitive functions using a broad range of established tests. Because of multiple comparisons, alpha was set at 1%.
Twenty six of 47 and 20/47 participants with AD showed evidence of stable or increased QoL-AD over 18 months according to self report and carer report. Logistic regression analyses showed that for every increase in one standardized score of California Verbal Learning Test-II short delay free recall the odds of stable/increased self-rated QoL-AD over 18 months were 0.27 (95%CI: 0.11, 0.67; p = 0.005). After adjustment for anxiety and depression, this inverse association no longer met the study criteria for statistical significance (adjusted OR: 0.31, 95%CI: 0.11, 0.86; p = 0.025). None of the other standardized changes of cognitive scores were associated with self-rated or carer-rated QoL-AD grouping.
Changes in specific cognitive functions are not associated with changes in HRQoL ratings in AD. Findings suggest that interventions that limit their focus to improving cognitive functions of people with mild to moderate AD living in the community might fail to have an impact on participants' HRQoL. Copyright © 2013 John Wiley & Sons, Ltd.