Cerebral Glucose Metabolism is Associated with Verbal but not Visual Memory Performance in Community-Dwelling Older Adults

Article type: Research Article

Authors: Gardener, Samantha L.^{a; b; 1} | Sohrabi, Hamid R.^{a; b; c; 1} | Shen, Kai-kai^{a; b; d} | Rainey-Smith, Stephanie R.^{a; b} | Weinborn, Michael^{a; b; e} | Bates, Kristyn A.^{b; f} | Shah, Tejal^{a; b} | Foster, Jonathan K.^g | Lenzo, Nat^{b; h} | Salvado, Olivier^d | Laske, Christophⁱ | Laws, Simon M.^{a; b; j} | Taddei, Kevin^{a; b} | Verdile, Giuseppe^{a; b; k} | Martins, Ralph N.^{a; b; c; *}

Affiliations: [a] Centre of Excellence for Alzheimer’s disease Research & Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia, Australia | [b] Sir James McCusker Alzheimer’s Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia | [c] School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia | [d] Australian eHealth Research Centre, Commonwealth Scientific and Industrial Research Organisation, Brisbane, Queensland, Australia | [e] School of Psychology, University of Western Australia, Crawley, Western Australia | [f] The School of Animal Biology, University of Western Australia, Crawley, WA, Australia | [g] Neurosciences Unit, Health Department of WA, School of Psychology and Speech Pathology, Curtin University of Technology, Perth, Western Australia, Australia | [h] Oceanic Medical Imaging, Hollywood Medical Centre, Nedlands, Western Australia, Australia | [i] Section for Dementia Research, Hertie Institute of Clinical Brain Research, Department of Psychiatry and Psychotherapy, University of Tübingen and German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany | [j] Cooperative Research Centre for Mental Health, Carlton, Victoria, Australia | [k] School of Biomedical Sciences, Faculty of Health Sciences, Curtin University of Technology, Bentley, Western Australia, Australia

Correspondence: [*] Correspondence to: Professor Ralph N. Martins, School of Medical Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, Western Australia 6027, Australia. Tel.: +61 8 9347 4200; Fax: +61 8 9347 4299; E-mail: ralph.n.martins@gmail.com.

Note: [1] These authors contributed equally to this work.

Abstract: Increasing evidence suggests that Alzheimer’s disease (AD) sufferers show region-specific reductions in cerebral glucose metabolism, as measured by [18F]-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET). We investigated preclinical disease stage by cross-sectionally examining the association between global cognition, verbal and visual memory, and 18F-FDG PET standardized uptake value ratio (SUVR) in 43 healthy control individuals, subsequently focusing on differences between subjective memory complainers and non-memory complainers. The 18F-FDG PET regions of interest investigated include the hippocampus, amygdala, posterior cingulate, superior parietal, entorhinal cortices, frontal cortex, temporal cortex, and inferior parietal region. In the cohort as a whole, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in both the left hippocampus and right amygdala. There were no associations observed between global cognition, delayed recall in logical memory, or visual reproduction and 18F-FDG PET SUVR. Following stratification of the cohort into subjective memory complainers and non-complainers, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in the right amygdala in those with subjective memory complaints. There were no significant associations observed in non-memory complainers between 18F-FDG PET SUVR in regions of interest and cognitive performance. We observed subjective memory complaint-specific associations between 18F-FDG PET SUVR and immediate verbal memory performance in our cohort, however found no associations between delayed recall of verbal memory performance or visual memory performance. It is here argued that the neural mechanisms underlying verbal and visual memory performance may in fact differ in their pathways, and the characteristic reduction of 18F-FDG PET SUVR observed in this and previous studies likely reflects the pathophysiological changes in specific brain regions that occur in preclinical AD.

Keywords: Brain glucose metabolism, cognition, ¹⁸F-FDG PET, subjective memory complaints, verbal memory, visual memory

DOI: 10.3233/JAD-151084

Journal: Journal of Alzheimer's Disease, vol. 52, no. 2, pp. 661-672, 2016