How does Parkinson's disease affect the mental state, especially thought processes?

Parkinson’s can affect mental state in many ways such as:

1.       slowness in thinking or bradycardia

2.       Difficulty in multitasking

3.       Executive dysfunction or impaired judgment and rigidity of thought process

4.       The dopamine agonists can lead to impulse control disorders like compulsive gambling, buying, hyper sexuality etc.

5.       Hallucinations are common in advanced disease, older age and increased dose of levodopa

Reference: Masoom Abbas