Olfactory dysfunction in dementia of Alzheimer's type and vascular dementia

Motomura, Naoyasu; Tomota, Yoji

doi:10.1111/j.1479-8301.2006.00119.x

Cited by 13 publications

(16 citation statements)

References 8 publications

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“…5,23,[27][28][29] Although the exact inception point of AD pathology in the olfactory system remains unknown, the disease course progressively involves 29 multiple levels of the olfactory system, 27,30 including peripheral structures such as the olfactory bulb and epithelium, as well as higher order olfactory pathways connected to cognitive processes. 25 Studies have shown greater OI deficits in patients with AD compared to those with vascular dementia, 31,32 suggesting that the site of vascular pathology may determine the type and severity of olfactory deficit, 33 with specific olfactory deficits observed only in patients whose corresponding olfactory structures sustained vascular damage, in contrast to the multiple-level impairment observed across the olfactory system in AD pathology. 25,27,30 Because we did not have detailed information on dementia subtype in this study, we could not investigate this further.…”

Section: Resultsmentioning

confidence: 99%

Olfaction and risk of dementia in a biracial cohort of older adults

et al. 2017

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Objective: Prior studies indicate that olfactory function may be an early marker for cognitive impairment, but the body of evidence has been largely restricted to white populations. Methods:We studied 2,428 community-dwelling black and white older adults (baseline age 70-79 years) without dementia enrolled in the Health, Aging, and Body Composition (Health ABC) study. Olfaction was measured as odor identification (OI) with the 12-item Cross Cultural Smell Identification Test in year 3. We defined incident dementia over 12 years on the basis of hospitalization records, prescription for dementia medication, or 1.5-SD decline in race-stratified global cognition score. We assessed dementia risk associated with OI score (by tertile) using Cox proportional hazards models. All analyses were stratified by race.Results: Poorer OI in older adults without dementia was associated with increased risk of dementia. After adjustment for demographics, medical comorbidities, and lifestyle characteristics, white participants in the poor or moderate OI tertile had greater risk of dementia (adjusted hazard ratio [HR] 3.34, 95% confidence interval [CI] 2.45-4.54; and HR 1.84, 95% CI 1.33-2.54, respectively) compared to those in the good tertile of function. Among blacks, worse OI was associated with an increased risk of dementia, but the magnitude of the effect was weaker (p for interaction 5 0.04) for the poor OI tertile (adjusted HR 2.03, 95% CI 1.44-2.84) and for the moderate tertile (adjusted HR 1.42, 95% CI 0.97-2.10). There was no interaction between OI and APOE e4 and risk of dementia.Conclusions: While the magnitude of the association was stronger in whites, we found that poor OI was associated with increased risk of dementia among both black and white older adults. Olfactory testing may be a simple, inexpensive, and highly sensitive method of identifying older adults at risk for developing dementia, particularly when combined with other early markers.

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Section: Resultsmentioning

confidence: 99%

Olfaction and risk of dementia in a biracial cohort of older adults

et al. 2017

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“…The olfactory system, which is one of the cardinal sensory gateways to the brain, is known to be dysfunctional in the very early stages of Parkinson’s disease (PD) and Alzheimer’s disease (AD) ( Rezek, 1987 ; Mesholam et al, 1998 ; Duff et al, 2002 ; Motomura and Tomota, 2006 ; Fusetti et al, 2010 ; Doty, 2012 ; Alves et al, 2014 ; Doty and Kamath, 2014 ). The pathological Lewy bodies are also shown in the olfactory bulb (OB) ( Li et al, 2016 ) and distributed to motor centers with the progression of the disease in PD ( Braak et al, 2003 ; Ross et al, 2008 ; Doty, 2012 ; Li et al, 2016 ).…”

Section: Introductionmentioning

confidence: 99%

Optimized Electrode Placements for Non-invasive Electrical Stimulation of the Olfactory Bulb and Olfactory Mucosa

et al. 2020

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The olfactory system is known to be dysfunctional in the early stages of Parkinson’s disease (PD) and Alzheimer’s disease (AD). It is also shown that intact olfactory function can be a key role player for regaining consciousness after brain injuries. Modulation of the olfactory regions has been attempted successfully with electrical stimulation over the years, either directly (transethmoidally, intraoperatively, internasally, etc.) or indirectly through the vagus nerve. We sought to develop a means of delivering optimized electrical stimulation to the olfactory region in a non-invasive fashion and in a way that is simpler, easier, and less cumbersome. The ultimate goal was to develop a system that would allow easier testing in future clinical trials presenting an opportunity to fully develop this potential treatment option. We devised six potential electrode placements leveraging commonly accepted facts of electrical stimulation, easier access through relatively higher conductive pathways into the brain, and practicality. Using an ultra-high-resolution finite element model, we screened each one of these montages for their ability to target the olfactory regions primarily and thereafter for select sub-cortical regions implicated in the pathogenesis of PD and AD. Modeling results indicate that some placements do result in inducing meaningful electric field magnitudes in the regions of interest. A practical headgear concept is proposed to realize the most ideal configuration. Our results pave the way for developing the first non-invasive electrical stimulation wearable system for targeting the olfactory regions which can help to alleviate the symptoms or suppress the progression of these neurological disorders.

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“…In addition, olfactory dysfunction is found to be a common complaint at the early stages of neurological diseases such as Alzheimer's disease (AD) and Parkinson' disease (PD), with more than 90% prevalence and higher incidence in men (Duff et al, 2002 ; Doty, 2012 ; Alves et al, 2014 ). Particularly with AD, odor discrimination (Fusetti et al, 2010 ) and identification abilities (Rezek, 1987 ; Motomura and Tomota, 2006 ), are impaired from the earliest stage of the disease. The presence of olfactory impairments at the early stage of AD has been linked to several factors occurring initially at the entorhinal cortex, one of the main terminals in the primary olfactory cortex.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Olfactory Function With High Frequency Non-invasive Auricular Electrostimulation in Healthy Humans

et al. 2018

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In past literature on animal models, invasive vagal nerve stimulation using high frequencies has shown to be effective at modulating the activity of the olfactory bulb (OB). Recent advances in invasive vagal nerve stimulation in humans, despite previous findings in animal models, used low frequency stimulation and found no effect on the olfactory functioning. The present article aimed to test potential effects of non-invasive, high and low frequency vagal nerve stimulation in humans, with supplementary exploration of the orbitofrontal cortex using near-infrared spectroscopy (NIRS). Healthy, male adult participants (n = 18) performed two olfactory tests [odor threshold test (OTT) and supra-threshold test (STT)] before and after receiving high-, low frequency vagal nerve stimulation and placebo (no stimulation). Participant's olfactory functioning was monitored using NIRS, and assessed with two behavioral olfactory tests. NIRS data of separate stimulation parameters were statistically analyzed using repeated-measures ANOVA across different stages. Data from olfactory tests were analyzed using paired parametric and non-parametric statistical tests. Only high frequency, non-invasive vagal nerve stimulation was able to positively modulate the performance of the healthy participants in the STT (p = 0.021, Wilcoxon sign-ranked test), with significant differences in NIRS (p = 0.014, post-hoc with Bonferroni correction) recordings of the right hemispheric, orbitofrontal cortex. The results from the current article implore further exploration of the neurocircuitry involved under vagal nerve stimulation and the effects of non-invasive, high frequency, vagal nerve stimulation toward olfactory dysfunction which showcase in Parkinson's and Alzheimer's Diseases. Despite the sufficient effect size (moderate effect, correlation coefficient (r): 0.39 for the STT) of the current study, future research should replicate the current findings with a larger cohort.

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Olfactory dysfunction in dementia of Alzheimer's type and vascular dementia

Cited by 13 publications

References 8 publications

Olfaction and risk of dementia in a biracial cohort of older adults

Olfaction and risk of dementia in a biracial cohort of older adults

Optimized Electrode Placements for Non-invasive Electrical Stimulation of the Olfactory Bulb and Olfactory Mucosa

Improvement of Olfactory Function With High Frequency Non-invasive Auricular Electrostimulation in Healthy Humans

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