Which neurotransmitter is notably decreased in early Parkinson's disease?

In early Parkinson's disease, the predominant neurotransmitter that is notably decreased is dopamine. This critical reduction occurs due to the degeneration of dopaminergic neurons in the substantia nigra, a key area of the brain involved in movement control. Dopamine is essential for facilitating smooth and coordinated muscle movements, and its deficiency leads to the characteristic motor symptoms of Parkinson's disease, such as tremors, rigidity, and bradykinesia.

While other neurotransmitters, such as serotonin and norepinephrine, may also be affected in Parkinson's disease, they do not play as central a role in the initial presentation of the motor symptoms as dopamine does. Acetylcholine levels can also be altered, but it is the decline in dopamine that is most closely associated with the early stages of the disease, making it the most notable neurotransmitter involved. Understanding the specific role of dopamine in this context helps clarify the pathophysiology of Parkinson's disease and the implications for treatment strategies aimed at managing its symptoms.