Which neurotransmitter is deficient in patients with Parkinson's disease?

Dopamine is the neurotransmitter that is deficient in patients with Parkinson's disease. This condition is primarily characterized by the degeneration of dopaminergic neurons in the substantia nigra, a region of the brain that plays a crucial role in movement control. The loss of dopamine leads to the hallmark symptoms of Parkinson's disease, such as bradykinesia (slowness of movement), rigidity, and tremors. The deficit in dopamine disrupts the balance between excitatory and inhibitory signals within the basal ganglia, which is essential for regulating smooth and coordinated movements.

While melatonin, acetylcholine, and vasopressin have important functions in the body, they are not the primary neurotransmitter involved in the pathology of Parkinson's disease. Melatonin is more related to sleep regulation, acetylcholine is associated with muscle activation and cognitive function, and vasopressin is involved in water retention and blood pressure regulation. Each of these neurotransmitters plays critical roles in different physiological processes, but dopamine deficiency is specifically linked to the motor symptoms observed in Parkinson's patients.