Self-Rated Quality of Life in Mild Cognitive Impairment and Alzheimer’s Disease: The Problem of Affective Distortion

Background: Cognitively impaired or demented patients may have difficulty performing the complex and multidimensional appraisal required by self-ratings (SR) of quality of life (QoL). Even healthy subjects often refer to their current mood state for QoL self-assessment. Therefore, it is hypothesized that patients rely on current mood state as a reference point for QoL SR, and that the degree of reliance increases with the level of cognitive impairment. Methods: Two consecutive samples of 14 patients with mild cognitive impairment (MCI) and 16 patients with Alzheimer’s disease (AD) were examined using the self-rated Dementia-Quality of Life (DEMQoL), a multidimensional mood state questionnaire (MDBF-A, Mehrdimensionaler Befindlichkeitsfragebogen), and the Mini-Mental State Examination (MMSE; MCI: mean = 25.1, SD = 2.1; AD: mean = 20.3, SD = 2.7). Results: As expected, correlations between current mood state and QoL SR (DEMQoL) were highly significant in AD patients but not in MCI patients. The degree of as...