Olfactory Dysfunction is Associated with Subjective Memory Complaints in Community-Dwelling Elderly Individuals

Article type: Research Article

Authors: Sohrabi, Hamid R.^{a; b} | Bates, Kristyn A.^{a; b; c} | Rodrigues, Mark^{a; b; c} | Taddei, Kevin^{a; b; c} | Laws, Simon M.^{c; d} | Lautenschlager, Nicola T.^{a; e; f} | Dhaliwal, Satvinder S.^g | Johnston, Amy N.B.^h | Mackay-Sim, Alan^h | Gandy, Samuelⁱ | Foster, Jonathan K.^{b; c} | Martins, Ralph N.^{a; b; c; *}

Affiliations: [a] The School of Psychiatry and Clinical Neuroscience, University of Western Australia, Crawley, WA, Australia | [b] The Sir James McCusker Alzheimer's Disease Research Unit, Hollywood Private Hospital, Nedlands, WA, Australia | [c] The School of Exercise, Biomedical and Health Science, Edith Cowan University, Joondalup, WA, Australia | [d] The Neurochemistry and Neurogenetics Laboratory, Department of Psychiatry and Psychotherapy, Technische Universität München (TU-München), München, Germany | [e] WA Centre for Health and Ageing, Western Australian Institute for Medical Research, University of Western Australia, Nedlands, WA, Australia | [f] Academic Unit for Psychiatry of Old Age, St Vincent's Health, Department of Psychiatry, University of Melbourne, Melbourne, Australia | [g] The School of Public Health, Curtin University of Technology, Perth, WA, Australia | [h] Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Australia | [i] Mount Sinai School of Medicine, New York, NY, USA

Correspondence: [*] Corresponding author: Prof. Ralph N. Martins, School of Exercise, Biomedical and Health Science, Edith Cowan University, 100 Joondalup Dr, Joondalup, WA 6027, Australia. Tel.: +61 08 6304 5456; Fax: +61 08 6304 5851; E-mail: r.martins@ecu.edu.au.

Abstract: Olfactory dysfunction has been reported in clinical and preclinical phases of Alzheimer's disease. Subjective memory complaints have been proposed as a potential early indicator for increased risk of Alzheimer's disease, but have also been associated with depression, personality characteristics, and health problems. In this study, we aimed to determine which of these putative markers can predict memory complaints in community-dwelling elderly individuals, focusing on olfactory symptoms. A cohort of 144 elderly volunteers (42 males and 102 females), aged 50 to 86, was recruited from an ongoing longitudinal study. Participants were assessed for olfactory capacities (threshold, discrimination, and identification), subjective memory complaints, depression, and cognitive functions. Subjective memory complaints were significantly associated with olfactory discrimination and identification but not with threshold. Olfactory functions and depressive symptoms were both significantly associated with subjective memory complaints. In addition, memory complainers were significantly worse than non-complainers with respect to olfactory discrimination, identification, and overall olfactory functioning. The findings suggest that olfactory capacity may be a potentially significant biomarker for identifying community-dwelling elderly with memory complaints who are at increased risk for age-related cognitive decline and Alzheimer's disease.

Keywords: Alzheimer's disease, cognitive decline, depression symptoms, olfactory dysfunction, smell identification, Sniffin' Sticks, subjective memory complaints

DOI: 10.3233/JAD-2009-1020

Journal: Journal of Alzheimer's Disease, vol. 17, no. 1, pp. 135-142, 2009