-Clinical Efficacy of Pharmacological Treatments Targeting Energy Metabolism, Evaluated by Gait Analysis, on Motor Function in Parkinson's Disease Patients

Bradykinesia, causing impairment of gait and an associated significant risk of falls, is among the most debilitating core features of Parkinson¿s disease (PD), a movement disorder characterized by the degeneration of Substantia nigra dopaminergic neurons. The pacemaking action potential firing activity of nigral neurons requires high energy consumption and is coupled to large cytosolic calcium oscillations, which influence mitochondrial respiration, energy metabolism, and reactive oxygen species (ROS) production. Mitochondrial dysfunction, on the other hand, can drive dysregulation of calcium homeostasis, especially in dopaminergic neurons, and is recognized as a key component in PD progression. Notably, both calcium-binding and increased ROS production, resulting from inefficiencies in the mitochondrial electron transport chain, can trigger alpha-synuclein aggregation, thus contributing to neuronal loss and disease progression in PD. The Nuclear factor erythroid 2- related factor 2 (Nrf2) is a regulator of mitochondrial function and biogenesis, and cellular resistance to oxidative stress. Bioactive compounds activating the Nrf2 signaling pathway ameliorate Parkinsonian phenotypes in experimental models, suggesting the Nrf2 pathway potential novel therapeutic target in PD.

Bradykinesia, causing impairment of gait and an associated significant risk of falls, is among the most debilitating core features of PD. PD gait is characterized by shuffling steps accompanied by a stooped posture. In advanced PD, other complications may arise such as disturbances in speech, gait, posture, and balance, as well as hypomimia, impaired decision-making, alertness, and regulation of emotions.

The increased energy demand associated with bradykinesia is coupled with the impairment of energy metabolism in Parkinsonians, negatively affecting walking, gait, and postural stability, suggesting that the modulation of mitochondrial energy metabolism may ameliorate gait and postural stability in Parkinsonians. Cardinal symptoms of PD: Tremors, Rigidity, Bradykinesia, and postural instability, all elements that lead in almost all patients to a walking disorder. In fact, walking in Parkinson's disease is present since in the early stages of the disease, the step is reduced in length and speed, the swinging phase of the step (swing) is reduced, while the support (Stance) single and double is increased in duration. Progression as well as the severity of disease over time, leads to a significant increase in the risk of falls, inducing a reduction in autonomy in daily living activity. As mentioned Gait is influenced in a principal way. Bipedal walking, in humans, is well orchestrated, consistent with the intrinsic "kinetic melody". This "melody" in subjects with PD is altered appears clear that the analysis of the gait represents a key element for establishing functional recovery therapies aimed at restoring motor skills. Therefore, it seems sensible to hypothesize that energy metabolism parameters may represent reliable biomarkers in PD and that the Nrf2 pathway may be a new therapeutic target for the recovery of motor function in PD patients. Not only that, but the identification of reliable biomarkers that are easy to measure over time can aid in the diagnosis, and possible prognosis, and improve management.

In support of this view, PD pathogenesis is known to involve the loss of the homeostatic functions controlling mitochondrial energy metabolism. The transcription factor Nrf2 is a master controller of these functions. Notably, Nrf2 activity is compromised during aging and in neurodegenerative diseases.

The investigators hypothesize that energy metabolism parameters may represent reliable biomarkers in PD and that the Nrf2 pathway may be a novel therapeutic target for the rescue of motor function in Parkinsonians.