What is the pathology of Parkinson's disease primarily associated with?

The pathology of Parkinson's disease is primarily associated with an imbalance between acetylcholine (ACh) and dopamine. In a healthy brain, these neurotransmitters work in concert within the basal ganglia to facilitate movement and motor control. In Parkinson's disease, there is a progressive degeneration of dopamine-producing neurons, specifically in the substantia nigra, which leads to a deficiency of dopamine. This deficiency disrupts the balance between ACh and dopamine; while dopamine levels decrease, ACh remains relatively unchanged or may even increase.

This imbalance is crucial because in Parkinson's disease, the reduced dopaminergic activity results in increased cholinergic (ACh) activity, contributing to the characteristic motor symptoms such as tremors, rigidity, and bradykinesia. Understanding this interplay is essential for managing the symptoms of the disease effectively, as treatments often aim to restore this balance.

The other options are not representative of the core pathology observed in Parkinson's disease. An excess of dopamine does not occur in this condition, nor does a deficiency of serotonin play a primary role in its pathology. While GABA is involved in the broader context of neural inhibition and balance, its increase is not directly tied to Parkinson's in the same fundamental manner as the ACh