How Does Impaired Brain Function Affect Cognitive Abilities in Parkinson’s Patients?

New Delhi, May 5 (NationPress) Researchers at the Indian Institute of Technology (IIT) Bombay have conducted a groundbreaking study revealing how disrupted brain activity influences cognitive abilities in individuals with Parkinson’s disease.

The research focused on the altered processing of rewards in Parkinson’s patients, aiming to understand the reasons behind their lack of motivation and compromised decision-making skills.

Parkinson’s disease is a neurodegenerative condition that primarily leads to symptoms such as tremors, muscle rigidity, and slowness of movement. However, many patients also experience a diminished sense of pleasure and motivation, which is linked to reduced levels of the dopamine hormone.

Dopamine, often referred to as the ‘feel-good’ hormone, is typically released during enjoyable activities or when rewards are received.

The deficiency of dopamine in Parkinson’s patients results in altered brain function and disrupted reward processing—the brain's capacity to recognize, appreciate, and respond to rewarding stimuli.

To explore reward processing, the research team utilized brain signals.

The findings indicated that reward positivity was significantly lower in patients with Parkinson’s, suggesting that their brains are less efficient at processing rewards. Reward positivity plays a crucial role in cognitive functions like attention, learning, and emotional responses.

Moreover, dopamine therapy did not succeed in restoring reward positivity.

“Under normal circumstances, the brain releases dopamine in short bursts following a reward, but in Parkinson’s, these bursts are less intense. While dopamine medication can replenish dopamine levels, it does not mimic the natural burst-like signals. This discrepancy may explain why dopamine alleviates motor symptoms but does not enhance cognitive functions such as reward processing,” explained Prof. Nivethida Thirugnanasambandam, who led the study at the Human Motor Neurophysiology and Neuromodulation Lab within the Department of Biosciences and Bioengineering.

“Thus, additional treatment strategies may be essential to address cognitive deficits in Parkinson’s,” she added.

The research team analyzed electroencephalography (EEG) data from 28 Parkinson’s patients and 28 healthy controls while they engaged in a reward-based learning task.

EEG recordings were taken from Parkinson’s patients both before and after receiving dopamine medication (ON condition). This comparative approach allowed researchers to assess the impact of dopamine treatment on reward processing.

Additionally, the analysis revealed that Parkinson’s patients exhibited reduced theta-gamma synchronization, leading to inefficient communication between brain regions responsible for processing rewards and utilizing that information for goal-directed behavior. This disruption may explain the observed lack of motivation and impaired decision-making in Parkinson’s patients.

The synchronization of theta and gamma waves is essential for cognitive functions such as reward processing and goal-oriented behavior.

While dopamine medication partially restored theta-gamma synchronization, this discovery underscores the potential of theta-gamma coupling as a biomarker for assessing impairments in reward mechanisms among Parkinson’s patients.