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Background. Non-motor symptoms (NMS) are an important early feature of Parkinson’s disease (PD), encompassing a variety of cognitive and neuropsychiatric symptoms, that seem to manifest differently depending on the asymmetry of motor symptoms. Different factors, such as uric acid (UA) and sex, also seem to influence NMS expression in PD. However, the interactions between UA, sex, and motor symptom asymmetry remains to be better understood in PD. Methods. Participants taking part in the Parkinson’s Progression Marker Initiative were studied based on the side of motor-symptom asymmetry and sex. Three-way interaction modeling was used to examine the moderating effects of sex and UA in time on NMS. Results. Significant three-way interactions were highlighted at one year follow-up between motor symptom asymmetry, UA and sex, for immediate memory, delayed memory, processing speed and sleepiness for female patients only. Also, female patients exhibiting predominantly right-sided motor symptoms demonstrated the most preserved NMS in the presence of lower serum UA levels. Conclusion. These findings suggest that in the earliest stages of the disease, serum UA and sex moderate NMS expression differently depending on motor asymmetry. This holds important clinical implications for symptom management in early-stage PD patients.

The longitudinal trajectories of cognitive-neuropsychiatric symptoms from the early stages of Parkinson's disease, as a function of motor symptom asymmetry at the onset of the disease, remain to be fully explored. Moreover, the relationship to biomarkers warrants further investigation.Non-motor and biospecimen data from 413 patients with Parkinson's disease, dissociating predominantly left-sided motor symptoms patients (n = 179), predominantly right-sided motor symptoms patients (n = 234), and matched healthy controls (n = 196), were extracted from the Parkinson's Progression Marker Initiative database during a 3-Year follow-up. Non-parametric and conservative corrections for multivariate comparisons were carried out on neuropsychiatric and biomarker data.A decline for global cognitive efficiency scores in predominantly right-sided motor symptoms patients was observed, whereas depressive and anxiety symptoms were greater overtime for predominantly left-sided motor symptoms patients. Biomarker analysis revealed that predominantly right-sided patients expressed decreased levels of total-tau and phospho-tau over time, while left-sided patients didn't differ from healthy controls.From the early course of the disease, the existence of different clinical phenotypes is proposed, associated to emerging evidences of distinct pathological pathways and a left-hemispheric vulnerability for cognitive decline.

Introduction Approximately 50% (between 16–74%) of adults with Parkinson’s disease (PD) show excessive daytime sleepiness. Besides its important role for vision, light conveys a powerful stimulating signal for alertness and cognition. Recent research has demonstrated that the blue part of light spectrum is the most efficient in enhancing vigilance and cognitive performance in young and older healthy individuals, thanks to a specific photoreception system within the eye which is particularly sensitive to blue wavelength. The aim of this pilot study was to compare the effects of blue-enriched light exposure (BL) and red-light placebo exposure (RL) on psychomotor vigilance and cognitive performance in adults with PD. Methods Sixteen participants with idiopathic PD (64.0±5.5 yrs, 6 women, Hoehn and Yahr status: 2) completed a brief neuropsychological assessment to exclude dementia, self-reported questionnaires and a complete eye examination in screening visits. The one-day experimental procedure included 1.25 h period of baseline dim-light exposition, followed by two light conditions presented in a counterbalanced design and separated by 15 minutes in dim-light: 1.25 h of BL at 959lux and 1.25 h of placebo RL condition at 472lux. Both light conditions were delivered by Luminette®. Data were normalized according to baseline dim-light evaluation. Mixed analyses of variance (2 light conditions X 2 orders) were performed to compare performance on an auditory psychomotor vigilance task (A-PVT) and an auditory 2-back cognitive tasks (A-2-back) during light exposure. Results We observed no significant effect of light conditions, orders and no interaction on reaction time (RT) and number of correct answers for the A-2-Back task. Furthermore, there was no significant difference between BL and RL on A-PVT performance including median RT, shift in optimum RT (i.e.,mean RT from fastest 10% RT), and duration of response in the lapse domain (i.e.,mean RT from slowest 10% RT). Conclusion These preliminary results do not support the notion that blue-enriched white light exposure is more efficient than red light exposure to stimulate psychomotor vigilance and cognitive performance in adults with PD. Next steps of analyses will compare the effects of BL and RL on subjective sleepiness and EEG cortical activation in the same population. Support (if any) CIHC & QPN