Cognitive Domains and Health-Related Quality of Life in Alzheimer’s Disease

Journals of Gerontology: Psychological Sciences cite as: J Gerontol B Psychol Sci Soc Sci, 2016, Vol. 71, No. 2, 275–287 doi:10.1093/geronb/gbu090 Advance Access publication August 5, 2014 Original Research Report Pascalle R. Bosboom1,2 and Osvaldo P. Almeida1,2 Western Australian Centre for Health and Ageing, Centre for Health Research and 2School of Psychiatry and Clinical Neurosciences, University of Western Australia, Perth, Australia. 1 Correspondence should be addressed to Pascalle R. Bosboom, MSc, Western Australian Centre for Health and Ageing (M573), University of Western Australia, 35 Stirling Highway, Crawley, Perth WA 6009, Australia. E-mail: . Received March 12, 2014; Accepted June 14, 2014 Decision Editor: Shevaun Neupert, PhD Abstract Objectives: The nature of the association between the cognitive decline and quality of life (QoL) during the course of Alzheimer’s disease (AD) has not been studied in detail. We designed this study to determine if the association between cognitive domains in AD and health-related quality of life (HRQoL) changed over 18 months. Methods: We recruited 80 community-dwelling older adults with mild to moderate AD and 61 healthy elderly controls as well as their next-of-kin. The primary outcome measure was the QoL-AD. Specific cognitive functions were assessed with a broad range of neuropsychological measures, which were later grouped into cognitive domains following factor analyses at the baseline and 18-month assessments. Other explanatory variables included demographics, psychopathology, burden of care, and use of medication. Results: Self-reported QoL-AD scores were not associated with any of the identified cognitive domains at either assessment. The cognitive domains of people with AD changed between baseline and the 18-month assessment, as did the association of these factors with carer-rated HRQoL. The HRQoL scores assigned by the next-of-kin declined alongside a general measure of cognitive function. Discussion: These results indicate that HRQoL is not consistently associated with specific cognitive domains in AD and that cognitive-enhancing focused therapies may fail to affect the HRQoL of people with AD. Key Words: Carer—Cognition—Episodic memory—Health-related quality of life—Quality of life-AD Cognitive impairment is a core feature of Alzheimer’s disease (AD) (McKhann et al., 2011) that is expected to undermine the health-related quality of life (HRQoL) of those affected (Banerjee et al., 2009; Droes et al., 2006; Jonker, Gerritsen, Bosboom, & Van Der Steen, 2004; Kaplan, Mausbach, Marcotte, & Patterson, 2010; Miche et al., 2014; Rabins, 2000). Specific cognitive deficits have been associated with diminished HRQoL in other chronic diseases, such as epilepsy, schizophrenia, Parkinson’s disease, traumatic brain injury, and multiple sclerosis (Anderson, Brown, Newitt, & Hoile, 2011; Barker-Collo, 2006; Hermann, 1993; Leroi, McDonald, Pantula, & Harbishettar, 2012; Perrine et al., 1995; Tolman and Kurtz, 2012) but, surprisingly, the relationship between the inevitable cognitive decline of AD and HRQoL during the course of the illness has not been studied in detail (Hoe, Hancock, Livingston, & Orrell, 2006; Logsdon, Gibbons, McCurry, & Teri, 2002; Novelli and Caramelli, 2010; Vogel, Mortensen, Hasselbalch, Andersen, & Waldemar, 2006). Few studies have investigated the longterm association between overall cognition and HRQoL in dementia (Bosboom, Alfonso, & Almeida, 2013; Heggie et al., 2012; Lyketsos et al., 2003; Missotten et al., 2007; Selwood, Thorgrimsen, & Orrell, 2005; Tatsumi et al., 2009; Vogel, Bhattacharya, Waldorff, & Waldemar, 2012). © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: . 275 Cognitive Domains and Health-Related Quality of Life in Alzheimer’s Disease 276 AD throughout the course of their illness). Conversely, if the underlying cognitive structure is not stable over time, then different cognitive domains might influence HRQoL as the disease progresses. This study aimed to determine whether: (a) the underlying cognitive structure in a sample of older adults with mild to moderate AD living in the community is stable over 18 months compared with controls free of dementia, and (b) the associations between cognitive structure and carer and self-reported HRQoL ratings remain stable over 18 months. Method Study Design This study was a 18-month longitudinal observational study of the HRQoL of older adults with AD and healthy older adults. Participants and Setting We recruited 80 community-dwelling volunteers with the diagnosis of probable AD according to National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association criteria (McKhann et al., 1984). All participants had a total score of 10 or more on the MMSE (Folstein, Folstein, & McHugh, 1975) at the time of enrolment. Carers had face-to-face contact with the person with AD at least three times per week over the preceding year. Participants were recruited from various mental health and aged care services in the Perth metropolitan area. Participants for the control group were aged 65 years or older and were recruited together with their next-of-kin from other studies running at the School of Psychiatry and Clinical Neurosciences. We only included cognitively intact control subjects, that is, volunteers who did not have cognitive complaints, with an MMSE of ≥26, and also did not meet criteria for AD or MCI. We included 65 control pairs in this study. We excluded people with a positive history of alcohol or substance abuse, and those with a medically unstable illness that could compromise survival (such as metastatic cancer). Participants with AD could be taking cholinesterase inhibitors or memantine, but could not be participating concurrently in an experimental study of medications for AD. All participants were competent in written and spoken English. Assessments were conducted between November 2006 and January 2010. The ethics committees of the University of Western Australia, Royal Perth Hospital, Mercy Hospital, and Western Australian Department of HealthNMAHS Mental Health approved the study protocol. All participants and their carers provided written informed consent, and the project was conducted in accordance with the Helsinki Declaration of Human Rights. However, their findings have relied on brief cognitive screening tests, such as the Mini-Mental State Examination (MMSE) and the Cambridge Cognitive Examination of the Elderly-Revised version (CAMCOG-R), which have limited sensitivity to measure specific cognitive functions, such as executive function (Kessels, Mimpen, Melis, & Rikkert, 2009; Martyr & Clare, 2012). A limited body of research using carer reports to measure the HRQoL of the AD patient they cared for has provided data suggesting that (...truncated)