Deficits in which neurotransmitter have been linked to Parkinson's disease?

Dopamine is the neurotransmitter that is most critically linked to Parkinson's disease. In Parkinson's disease, there is a significant loss of dopamine-producing neurons in the substantia nigra, which is part of the basal ganglia in the brain. This loss leads to the motor symptoms characteristic of the disease, including tremors, rigidity, and bradykinesia (slowness of movement).

Dopamine plays a key role in regulating movement and coordination. As dopamine levels decrease, the balance between excitation and inhibition in the brain's motor circuits is disrupted, resulting in the motor deficits observed in individuals with Parkinson's. Thus, the connection between dopamine deficits and the symptoms of Parkinson's disease is well-established in both clinical and research settings.