Anosmia, a precious indicator in Parkinson’s disease

Retain – Anosmia, precious indicator parkinson's disease

• According to a Literature reviewsmell disorders are among the most frequent non -motor symptoms in subjects with Parkinson’s disease.
• Present years before the appearance of the first motor symptoms, they could be associated with the appearance of the first aggregates of alpha-synuclein in the olfactory bulb.
• The evaluation of these olfaction disorders could contribute to the differential diagnosis of Parkinson’s disease.
• Anosmia also seems to be correlated with the evolution of the disease and the quality of life of patients.

The diagnosis of Parkinson’s disease is essentially based on patient’s medical history and clinical examination. Consequently, For the moment, no biological or specific imaging marker is yet available in clinic. Meanwhile, Certain prodromal signs often precede several years the appearance of anosmia, precious indicator parkinson’s disease the first motor symptoms. Nevertheless, such as anosmia, constipation, disorders of paradoxical sleep or depressive symptoms.

The olfactory bulb, a starting point for alpha-synucleopathy

Sleeping disorders are present early in 90 % of patients who develop the disease. Nevertheless, It has been shown that they could allow distinguish parkinsonian subjects in the early phase of healthy subjectswith a sensitivity varying from 61 to 95 %. In addition, a specificity of 66 to 99 %. At the pathophysiological level. they could be correlated with the initiation of the degeneration of the dopaminergic neurons of the black substance and the first aggregates of alpha-synuclein were observed in the olfactory bulb (as well as in the dorsal engine nucleus of the vagus nerve). These aggregates could be responsible for early smell disorders. More generally. many epidemiological, clinical, histological and imaging results designate the anosmia, precious indicator parkinson’s disease olfactory bulb as an inaugural site for the development of Parkinson’s disease, even if the entry routes of alpha-synuclein fibrils towards other brain structures can be multiple (wains in particular). Thus, the evaluation of olfactory disorders is today envisaged to contribute to the diagnosis of Parkinson’s disease.

Loss of smell as a diagnostic. prognostic marker

According to researchers from the Lyon neuroscience research center, anosmia concerns 9 % of French and increases beyond 50 years to reach 20 % among those over 65. An alteration of smell cannot therefore be considered as a specific marker of the disease. but it could Help Parkinson’s disease differentiate and other causes of parkinsonism In the future, subject to improving the sensitivity of olfactory tests. A prospective study has also shown that Hyposmic Parkinsonian patients followed a more pejorative anosmia, precious indicator parkinson’s disease trajectory than others. suggesting that smell disorders could also serve as Prognostic markers to predict the evolution of the disease. Finally. the fact that the disorders of smell are associated with other non -motor symptoms, such as apathycould be useful for assessing quality of life.