Cognition Deficits in Parkinson’s Disease: Mechanisms and Treatment

Authors: Congcong Fang et al. (2020)

Link: https://onlinelibrary.wiley.com/doi/10.1155/2020/2076942

Background Information:

Parkinson’s disease (PD) is commonly known for movement problems—like tremors, stiffness, and slow motions—but many patients also experience cognitive issues, including memory loss, poor planning, and trouble focusing. Up to 50% of people with PD develop mild cognitive impairment within five years, and many progress to full dementia, which greatly impacts daily living and quality of life.

Purpose of the Study:

This review aimed to better explain why cognitive problems occur in PD and to gather current information on treatments. The authors focused on defining what kinds of cognitive deficits appear, understanding the brain and chemical changes behind them, and evaluating both drug treatments and non-drug strategies that might help preserve or improve thinking abilities in people with PD.

Methods and Data Analysis:

The authors analyzed existing studies on brain chemistry, genetic factors, and brain imaging to explore the causes of cognitive decline in PD. They reviewed clinical trials and observational studies testing various treatments—including cholinesterase inhibitors (like rivastigmine), dopamine-related drugs, lifestyle interventions, and brain stimulation techniques such as transcranial magnetic stimulation (rTMS). Their goal was to assess which approaches show the most promise.

Key Findings and Conclusions:

The review found that cognitive problems in PD are not due only to dopamine loss; other brain chemicals—like acetylcholine and noradrenaline—are also involved. Genetic mutations (e.g., GBA, APOE) and overlapping protein changes seen in Alzheimer’s also contribute. Among treatments, cholinesterase inhibitors and memantine have consistently improved cognition in PD dementia, albeit modestly. Physical exercise, cognitive training, and brain stimulation offer additional benefits in selected cases. However, dopamine-specific medications and other supplements have shown inconsistent effects.

Applications & Limitations:

In practice, this review suggests doctors should regularly check thinking skills in PD patients—starting early in the disease—so that treatments can begin promptly. It supports using cholinesterase inhibitors in patients with dementia, and considering non-drug interventions like exercise and brain stimulation. Yet, the evidence is still limited: study sizes are small, and it's unclear how long any benefits last. More research is needed to understand which therapies work best for specific types of cognitive issues in PD and to explore new drug targets like norepinephrine or mitochondrial health.