[Early recognition of Parkinson's disease. Objectifiable non-motor symptoms and biomarkers]

Colonoscopy and Subsequent Risk of Parkinson's Disease

Background

Parkinson's disease (PD) is caused by the misfolding and aggregation of α-synuclein in neurons into toxic oligomers and fibrils that have prion-like properties allowing them to infect healthy neurons and to be transmitted to animal models of PD by injection or oral exposure. Given α-synuclein fibrils' potential transmission on the gut-brain axis, α-synuclein may be transmitted through colonoscopy procedures.

Objective

This study examines a possible association between colonoscopy and PD.

Methods

Longitudinal health insurance data of 250,000 individuals aged 50+ from 2004-2019 was analyzed. Cox proportional hazard and competing risk models with death as a competing event were estimated to calculate the risk of PD. Colonoscopy was categorized as never receiving colonoscopy, colorectal cancer (CRC) screening without or with biopsy, destruction or excision (BDE), and diagnostic colonoscopy without or with BDE.

Results

We identified 6,422 new cases of PD among 221,582 individuals. The Cox model revealed a significantly increased risk of PD for patients who ever had a diagnostic colonoscopy without or with BDE (HR = 1.31; 95% CI: [1.23-1.40]; HR = 1.32 [1.22-1.42]) after adjustment for age and sex. After controlling for covariates and death, persons who ever underwent CRC screening had a 40% reduced risk of PD (CRHR = 0.60 [0.54-0.67]), while persons who underwent diagnostic colonoscopy had a 20% reduced risk of PD (CRHR = 0.81 [0.75-0.88]).

Conclusions

Colonoscopy does not increase the risk of PD, after adjusting for death and covariates. Individuals who underwent only CRC screening had the lowest risk of PD, which may be a result of a more health-conscious lifestyle.

Stress and corticosterone alter synaptic plasticity in a rat model of Parkinson's disease

As a major influence on neuronal function and plasticity, chronic stress can affect the progression and symptoms of neurodegenerative conditions, such as Parkinson's disease (PD). Here we investigated the influence of unilateral dopamine depletion and stress on dopamine-related hallmarks of stress response and neuronal plasticity in a rat model of PD. Animals received either restraint stress or a combination of adrenalectomy and corticosterone (CORT) supplementation to clamp circulating glucocorticoid levels for three weeks prior to unilateral nigrostriatal dopamine depletion. Rats were tested in skilled and non-skilled motor function up to three weeks post-lesion. Midbrain mRNA expression assessments included markers of dopamine function and neuroplasticity, such as tyrosine hydroxylase (TH), synaptophysin (SYN), calcyon, and glucocorticoid receptor (GR). Along with impaired motor performance, stress and clamped CORT partially preserved TH expression in both substantia nigra (SN) and ventral tegmental area (VTA), but differentially modulated the expression of SYN, calcyon, and GR mRNA in midbrain and cortical areas. Stress reduced synaptophysin mRNA expression in SN/VTA, and elevated calcyon mRNA optical density in both non-lesion and lesion hemispheres. Stress and CORT increased GR mRNA in the non-lesion SN/VTA, while in the lesion hemisphere GR mRNA was only elevated by CORT. In the motor cortex and striatum, however, GR was higher in both hemispheres under both experimental conditions. These findings suggest that stress and stress hormones differentially affect dopaminergic function and neuroplasticity in a rat model of PD. The findings suggest a role for stress in motor and non-motor symptoms of PD and stress response.

Association between Community Ambulation Walking Patterns and Cognitive Function in Patients with Parkinson's Disease: Further Insights into Motor-Cognitive Links

Background. Cognitive function is generally evaluated based on testing in the clinic, but this may not always reflect real-life function. We tested whether parameters derived from long-term, continuous monitoring of gait are associated with cognitive function in patients with Parkinson's disease (PD). Methods. 107 patients with PD (age: 64.9 ± 9.3 yrs; UPDRS motor sum “off”: 40.4 ± 13.2; 25.23% women) wore a 3D accelerometer on their lower back for 3 days. Computerized measures of global cognitive function, executive function, attention, and nonverbal memory were assessed. Three-day acceleration derived measures included cadence, variability, bilateral coordination, and dynamic postural control. Associations between the acceleration derived measures and cognitive function were determined. Results. Linear regression showed associations between vertical gait variability and cadence and between global cognitive score, attention, and executive function (p ≤ 0.048). Dynamic postural control was associated with global cognitive score and attention (p ≤ 0.027). Nonverbal memory was not associated with the acceleration-derived measures. Conclusions. These findings suggest that metrics derived from a 3-day worn body-fixed sensor reflect cognitive function, further supporting the idea that the gait pattern may be altered as cognition declines and that gait provides a window into cognitive function in patients with PD.