Objectives: The present study investigates the effect of anosognosia (impaired insight for an illness) and cognitive deficits on the reliability and validity of self-rated Quality of Life (QoL) in Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD).
Design: Cross-sectional study.
Setting: Cross-sectional study with a consecutive clinical sample from a memory clinic in Leipzig (Germany).
Subjects: 27 patients (aged 65 years or above) with a diagnosis of either MCI (N=12) or AD (N=15), each together with a caregiver.
Measurements: The patients' QoL was measured using the Dementia Quality of Life self and proxy ratings (DEMQoL and DEMQoLproxy). The degree of anosognosia was rated by means of the Clinical Insight Rating Scale (CIR). In addition the Mini-Mental-State Examination (MMSE), and for diagnostic purposes the Bayer Activities of Daily Living Scale (B-ADL) and the Consortium to Establish a Registry of Alzheimer;s Disease (CERAD) word list were applied.
Results: In accordance with the results of Ready et al. (1), patients with impaired insight were found to produce less reliable QoL ratings than those with unimpaired insight. The validity (concordance between self- and proxy QoL ratings) is influenced by cognitive deficits, anosognosia and the interaction between these factors.
Conclusions: Data which are based on dementia patients' QoL self-ratings need to be interpreted with caution when anosognosia is present.