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Related Concept Videos

Parkinson Disease ll: Pathophysiology01:24

Parkinson Disease ll: Pathophysiology

Parkinson disease (PD) is a progressive neurodegenerative disorder primarily affecting movement, with additional non-motor features. Its pathophysiology involves complex interactions among genetic susceptibility, environmental exposures, and cellular dysfunction, including dopaminergic neuron loss, protein aggregation, and mitochondrial impairment.Selective NeurodegenerationA key feature is the degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to reduced...
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Parkinson's Disease: Treatment

Neurodegenerative disorders, such as Parkinson's Disease (PD), involve the gradual and irreversible destruction of neurons in particular brain areas. These disorders exhibit standard features like proteinopathies, selective vulnerability of some neurons, and an interaction of intrinsic properties, genetics, and environmental influences in neural injury.
Parkinson's Disease is primarily a result of the loss of dopaminergic neurons in the substantia nigra pars compacta. The cornerstone of its...
Olfactory Receptors: Location and Structure01:03

Olfactory Receptors: Location and Structure

The process of olfaction, also known as the sense of smell, is a sophisticated chemical response system. The specialized sensory neurons that facilitate this process, known as olfactory receptor neurons, are situated in an upper segment of the nasal cavity, known as the olfactory epithelium. Olfactory sensory neurons are bipolar, with their dendrites extending from the epithelium's apex into the mucus that lines the nasal cavity. Airborne molecules, when inhaled, traverse the olfactory...
Parkinson's Disease: Overview01:15

Parkinson's Disease: Overview

Neurodegenerative disorders are progressive diseases that cause irreversible damage and loss to neurons in specific brain areas. Examples of these disorders include Parkinson's disease, Alzheimer's disease, Multiple Sclerosis (MS), and Amyotrophic Lateral Sclerosis (ALS). These disorders share characteristics such as proteinopathies, selective neuronal vulnerability, and a complex interplay between genetic and environmental factors. The primary therapeutic goal for these conditions is to...
Parkinson Disease l: Introduction01:24

Parkinson Disease l: Introduction

Parkinson’s disease is a chronic, progressive neurodegenerative disorder that primarily affects movement. It is characterized by motor symptoms such as resting tremors, muscle rigidity, bradykinesia (slowness of movement), and postural instability. Patients may notice hand tremors at rest, stiffness during movement, or a shuffling gait. In addition to motor features, non-motor symptoms include sleep disturbances, mood and behavioral changes, constipation, and cognitive impairment, all of which...
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The olfactory receptors are embedded in the cilia of the...

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Related Experiment Video

Updated: May 22, 2026

Olfactory Assays for Mouse Models of Neurodegenerative Disease
07:27

Olfactory Assays for Mouse Models of Neurodegenerative Disease

Published on: August 25, 2014

Olfactory dysfunction in Parkinson disease.

Richard L Doty1

  • 1Smell and Taste Center, University of Pennsylvania School of Medicine, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA. doty@mail.med.upenn.edu

Nature Reviews. Neurology
|May 16, 2012
PubMed
Summary
This summary is machine-generated.

Olfactory dysfunction, a common early sign of Parkinson disease (PD), may stem from neurochemical deficits. Understanding smell loss in PD aids differential diagnosis and research into disease mechanisms.

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Area of Science:

  • Neuroscience
  • Neurology
  • Ophthalmology

Background:

  • Olfactory dysfunction is a prevalent early nonmotor symptom in Parkinson disease (PD), affecting up to 90% of early-stage patients.
  • This sensory deficit can manifest years before the onset of characteristic motor symptoms in PD.
  • Similar olfactory deficits in other neurodegenerative conditions suggest a potential shared pathological basis.

Purpose of the Study:

  • To review the current understanding of olfactory dysfunction in Parkinson disease.
  • To explore potential mechanisms and neuroanatomical correlates of smell loss in PD.
  • To discuss the utility of olfactory testing in the differential diagnosis of parkinsonian syndromes.

Main Methods:

  • Literature review of studies on olfactory dysfunction in Parkinson disease and related disorders.
  • Analysis of neuroanatomical findings, including neuronal loss in specific brainstem nuclei.
  • Correlation of olfactory deficits with neurochemical changes, particularly in cholinergic, noradrenergic, and serotonergic systems.

Main Results:

  • Olfactory dysfunction is a hallmark of early Parkinson disease, often preceding motor symptoms.
  • Reduced neuronal counts in the locus coeruleus, raphe nuclei, and nucleus basalis of Meynart are associated with smell loss in PD.
  • Olfactory testing can help differentiate PD from other parkinsonian disorders like multiple system atrophy and progressive supranuclear palsy.

Conclusions:

  • The mechanisms underlying olfactory dysfunction in PD are not fully elucidated but may involve deficits in cholinergic, noradrenergic, and serotonergic pathways.
  • Shared pathological substrates might explain similar olfactory deficits observed in Alzheimer disease and Down syndrome.
  • Olfactory testing serves as a valuable diagnostic tool for Parkinson disease and related neurological conditions.