An American study on 6108 men shows that a triad of non -motor symptoms multiplies by 23 the risk of developing a parkinson within 3 years. These prodromal markers could pave the way for early screening for the general population.
Parkinson’s disease progresses insidiously for years before the first motor symptoms allow its diagnosis. At this stage, the alteration of dopaminergic neurons is already well advanced, limiting the effectiveness of treatments. Identify patients during this early (or prodromic) phase of the disease thus represents a major issue to improve the management of this neurodegenerative pathology.
A whole range of non -motor signs have been described during this prodromic phase, including neuropsychiatric, sleep or even sensory disorders. Strategies to predict Parkinson’s disease, based on characteristic combinations, have already been proposed, but targeting high -risk populations (especially according to a specific genetic profile).
A new prospective American study brings encouraging elements by demonstrating that a combination of three non -motor symptoms makes it possible to predict with precision the appearance of Parkinson’s disease in the following years.
A particularly discriminating predictive triad
This prospective longitudinal study focused on 6108 men aged 40 to 75, health professionals, the HPFS cohort (Health Professionals Follow-Up Study) In the United States, with repeated assessments in 2012, 2014 and 2017. From the literature data, seven non-motor characteristics have been studied (constipation, paradoxical sleeping disorder, hyposmie, alteration of color vision, daytime sleepiness, body pain and depressive symptoms), three of which were particularly discriminating. Composite measures have also been calculated.
Co-competition of constipation, a downturn in sleep in paradoxical (TCSP) and the hyposmy multiplies by 23 the risk of diagnosis of Parkinson in the following three years (RR = 23.35 [IC 95 % : 10,62-51,33]). This association remains statistically significant even after adjustment to the risk factors and known protectors, such as smoking, physical activity, caffeine consumption and diabetes, with a relative risk of 25.33 [11,60-55,32].
During an average follow -up of 3.4 years, 103 participants developed a Parkinson disease. Among men with the symptomatic triad (constipation, TCSP, hyposmie), 12.5 % [6,6-18,4] evolved towards a clinically manifest parkinson within three years, against only 0.5 % in the group unharmed by these characteristics.
Validation of MDS criteria and identification of prodromal subtypes
The study also validates the Bayesian approach developed by the Movement Disorders Society (MDS), which integrates risk factors and prodromal markers. Men with a probability of Parkinson Prodromique ≥ 0.8 according to these criteria present a risk 21 times higher compared to those with a probability <0.2 (RR = 21.96 [11,17-43,17]). COOCCECTION OF THE 3 non -motor characteristics and a probability based on MDS (≥ 0.8) had comparable predictive values ​​and were stronger predictors than any of the characteristics taken in isolation. Thus, the proportion of individuals who were phenoconverted within 3 years was 12.5 % in men with the 3 non -motor characteristics, and 13.9 % (95 % CI = 8.5 to 19.5) in men with probable parkinson prodromic disease.
Temporal analysis shows a notable increase in symptoms in the two years preceding the diagnosis: the proportion of individuals presenting the symptomatic triad goes from 13% to 22%, while the median MDS double score. This development confirms the interest of longitudinal monitoring to optimize prediction.
Associations are particularly robust in men under the age of 75, suggesting better predictive performance in this population. This observation could guide screening strategies to younger subjects with these prodromal characteristics.
Two distinct subtypes of Parkinson Prodromic have also been identified for which the TCSP and the alteration of the vision of colors constituted the main discriminating elements. These data suggest heterogeneity of the prodromic phase which could refer to personalized therapeutic strategies.
This prospective study, which relates only to professional health men, however, demonstrates for the first time that a simple evaluation of non -motor symptoms could identify with good precision individuals at risk of developing a parkinson disease. The predictive value of these tools comparable to that of colorectal or prostatic cancer screening tests, opens up concrete perspectives for the implementation of population screening strategies, if it is confirmed in a more varied population.
These results could revolutionize the preventive approach to Parkinson’s disease by allowing early identification of patients candidates for therapeutic neuroprotection trials, before the appearance of irreversible lesions.
