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Aim: Olfactory impairment as a prodromal symptom, as well as sarcopenia, frailty and dependence as geriatric syndromes, is often associated with cognitive decline in older adults with progression of Alzheimer's disease. The present study aimed to evaluate the associations of olfactory and cognitive decline with these geriatric syndromes, and with structural changes of the brain in older adults., Methods: The participants were 135 older adults (47 men and 88 women, mean age 79.5 years), consisting of 64 with normal cognition, 23 with mild cognitive impairment and 48 with Alzheimer's disease. Olfactory function was evaluated by the Open Essence odor identification test. Shrinkage of the regional brain was determined by magnetic resonance imaging., Results: Logistic regression analysis with Open Essence, Mini-Mental State Examination, age and sex as covariates showed higher olfactory-cognitive index (|coefficient for Open Essence (a) / coefficient for Mini-Mental State Examination (b)|) in participants with sarcopenia (Asia Working Group for Sarcopenia), and lower values of (|a/b|) in participants with Barthel Index dependence, Kihon Checklist frailty, Lawton Index dependence and support/care-need certification as objective variables. Logistic regression analysis adjusted by age and sex also showed significant shrinkage of the frontal lobe in participants with AWGS sarcopenia, especially in women, and shrinkage of the medial temporal areas and global brain in participants with Kihon Checklist frailty/dependence., Conclusions: Olfactory-cognitive index (|a/b|) might be a useful tool to distinguish involvement of frontal lobe shrinkage, as in sarcopenia from shrinkage of the medial temporal areas, and global brain, as in frailty/dependence, in older adults with progression of normal cognition to Alzheimer's disease. Geriatr Gerontol Int 2021; ••: ••-••., (© 2021 The Authors. Geriatrics & Gerontology International published by John Wiley & Sons Australia, Ltd on behalf of Japan Geriatrics Society.)

Objective: To investigate the differences in regions of brain activation in response to olfactory stimulation by functional magnetic resonance imaging in conditions of prior warning of an odor and without., Methods: Participants were 17 normal right-handed volunteers; 8 participants received prior warning of the odor (informed condition) and 9 participants were not pre-warned (naïve condition). The odorant used was isovaleric acid., Results: In the informed condition with prior warning, activation was observed in the putamen extending to the insula, amygdala, and inferior frontal gyrus, and there was instant reification of the odor, while in the naïve condition without prior warning, activation was observed in the anterior cingulate cortex, entorhinal cortex, putamen and inferior frontal gyrus, and recognition of the odor was difficult., Conclusions: These results suggest that the condition prior to olfactory stimulation, i.e., with or without prior warning, can affect recognition and regions of brain activation in response to olfactory stimulation using isovaleric acid. Differences in recognition and regions of brain activation between both conditions could be associated with response latencies, or degree of attention, expectation and/or concentration.

Objective: Olfactory dysfunction is common in patients with mild cognitive impairment (MCI) or Alzheimer's disease (AD). We sought to elucidate brain regions associated with olfactory dysfunction in patients with MCI and early AD by using 123I-IMP-SPECT to detect regional cerebral blood flow (CBF).Methods: We included 218 patients diagnosed with AD or MCI, who underwent a comprehensive battery of neuropsychiatric and neuropsychological tests, Alzheimer's Disease Assessment Scale-Cognitive Part (ADAS-Cog), and forward- and backward-digit span. Olfactory function was assessed using T&T olfactometry of five odors; patients stated whether they experienced any smell (detection test) and identified the odor (identification test). The association between single-photon emission computerized tomography based regional CBF and olfactory function was examined by voxel-by-voxel multiple regression analysis, considering sex, age, and education as covariate parameters.Results: Of the 218 patients, 78 had mildly impaired olfactory detection and 15 had olfactory detection loss; additionally, 213 had mild olfactory identification impairment. The odor detection score correlated significantly with the ADAS-Cog word recall score (r = 0.193, p = 0.004). The odor identification score correlated significantly with the ADAS memory (r = 0.408, p < 0.001) and ADAS orientation (r = 0.292, p < 0.001) scores. The odor identification score correlated negatively with CBF in the left temporal pole, entorhinal area, and bilateral frontal poles (p < 0.001).Conclusion: Olfactory identification dysfunction in patients with MCI and AD is attributable to reduced CBF of the left temporal pole, entorhinal area, and bilateral frontal pole. [ABSTRACT FROM AUTHOR]