Olfactory Deficits and Cognitive Dysfunction in Parkinson’s Disease

Parrao, Teresa; Chaná, Pedro; Venegas, Pablo; Behrens, María Isabel; Aylwin, Maria Luz

doi:10.1159/000335915

Cited by 33 publications

(26 citation statements)

References 23 publications

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“…Therefore, our transgenic mouse model with late Thy1-A30P α-SYN expression reflects, in part, the pathology observed in brains of PD patients with Lewy bodies in MCs of the OB78, the human olfactory deficit at an early stage of the disease process123 and a lack of progenitor cells10. Importantly, our results support the previously reported association between adult neurogenesis and fine odour discrimination495758; although we still lack the molecular and cellular mechanism to explain olfactory deficits in these mice59.…”

Section: Discussionmentioning

confidence: 94%

“…Hyposmia is one of the most frequent non-motor symptoms of Parkinson disease (PD)123, being detected in the majority of PD patients several years before the first appearance of motor symptoms4. Moreover, deposition of fibrillar α-synuclein (α-SYN) aggregates56 - the main pathological hallmark of the disease - occurs inside olfactory bulb (OB) neurons of PD patients78.…”

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confidence: 99%

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A30P α-Synuclein interferes with the stable integration of adult-born neurons into the olfactory network

Neuner

Filser

Michalakis

et al. 2014

Sci Rep

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Impaired olfaction is an early symptom in Parkinson disease (PD), although the exact cause is as yet unknown. Here, we investigated the link between PD-related mutant α-Synuclein (α-SYN) pathology and olfactory deficit, by examining the integration of adult-born neurons in the olfactory bulb (OB) of A30P α-SYN overexpressing mice. To this end, we chose to label one well-known vulnerable subpopulation of adult-born cells, the dopaminergic neurons. Using in vivo two-photon imaging, we followed the dynamic process of neuronal turnover in transgenic A30P α-SYN and wild-type mice over a period of 2.5 months. Our results reveal no difference in the number of cells that reach, and possibly integrate into, the glomerular layer in the OB. However, in mutant transgenic mice these new neurons have a significantly shortened survival, resulting in an overall reduction in the addition of neurons to the glomerular layer over time. We therefore propose unstable integration and impaired homeostasis of functional new neurons as a likely contributor to odour discrimination deficits in mutant α-SYN mice.

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Section: Discussionmentioning

confidence: 94%

mentioning

confidence: 99%

A30P α-Synuclein interferes with the stable integration of adult-born neurons into the olfactory network

Neuner

Filser

Michalakis

et al. 2014

Sci Rep

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“…Similarly, Haehner et al () showed that patients with Parkinson's disease with an impairment of verbal fluency improved after OT. Also, Parrao et al () assumed a close association between cognitive function and olfactory function in Parkinson's disease.…”

Section: Discussionmentioning

confidence: 99%

Olfactory training with older people

Birte-Antina

Croy

Hähner

et al. 2017

Int J Geriat Psychiatry

113

102

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Background/objectives: Loss of olfactory function is largely found with aging. Such a reduction in olfactory function affects quality of life and enhances likelihood of depressive symptoms. Furthermore, it has been shown that reduction in olfactory function is associated with cognitive impairment and several diseases such as major depression. Because several studies suggest that discontinuous exposure to odors may improve general olfactory function, the primary aim of this study was to investigate whether such "olfactory training" has positive effects on subjective well-being and cognitive function. Design: We performed a controlled, unblinded, longitudinal study Setting: The study took place at an outpatients' clinic of a Department of Otorhinolaryngology at a Medical University. Participants: A total of 91 participants (age 50 to 84 years) completed testing. They were randomly assigned to an olfactory training (OT) group (N = 60) and a control group (N = 31). The study included two appointments at the Smell and Taste Clinic. Measurements: Olfactory and cognitive function as well as subjective well-being was tested using standardized tests. Intervention: During the 5-month interval between sessions, the OT group completed daily olfactory exposure. During the same time, the control group completed daily Sudoku problems. Results: Analyses show a significant improvement of olfactory function for participants in the OT group and improved verbal function and subjective well-being. In addition, results indicated a decrease of depressive symptoms. Conclusion: Based on the present results, OT may constitute an inexpensive, simple way to improve quality of life in older people.

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“…Therefore, it may be hypothesized that this specific effect on odor discrimination relates to the interaction between cognitive and olfactory function. Recent research by Damholdt et al (2011) and Parrao et al (2012) suggested that there is a close association between cognitive function and olfactory function in PD patients. This might be a further hint to the beneficial effect of rasagiline on human cognition, which was recently described by Hanagasi et al (2011).…”

Section: Discussionmentioning

confidence: 99%

Early Parkinson’s disease patients on rasagiline present with better odor discrimination

et al. 2015

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The effects of rasagiline on olfaction in animal studies are convincing. However, apart from various anecdotal patient reports, they could not be reproduced in prospective studies in humans. Cross-sectional data of large patient groups are still missing. The aim of this study was therefore to determine the olfactory function in a broad heterogeneous Parkinson's disease (PD) population with and without rasagiline intake. In this single-center, cross-sectional study 224 PD patients with and without rasagiline (1 mg/day) participated. Seventy-four of them received rasagiline as mono, or adjunct therapy. One-hundred fifty patients were untreated or received PD medication other than rasagiline. Comprehensive olfactory testing was performed for phenyl-ethyl alcohol odor thresholds, odor discrimination, and odor identification. Olfactory function did not differ between the two treatment groups with disease duration up to 29 years. Rasagiline-treated patients with disease duration of less than 8 years, however, presented with significant better odor discrimination abilities compared to PD patients without rasagiline treatment. This effect was no longer evident in patients with longer disease duration and proofed to be independent of age, sex, and medication. Our results may suggest that rasagiline treatment has a positive effect on the processing of olfactory information in early PD.

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Olfactory Deficits and Cognitive Dysfunction in Parkinson’s Disease

Cited by 33 publications

References 23 publications

A30P α-Synuclein interferes with the stable integration of adult-born neurons into the olfactory network

A30P α-Synuclein interferes with the stable integration of adult-born neurons into the olfactory network

Olfactory training with older people

Early Parkinson’s disease patients on rasagiline present with better odor discrimination

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