AEMCA Practice Exam

Which factor contributes to the symptoms of Parkinson's disease?

1. Excessive dopamine levels

2. Decreased levels of serotonin

3. Decreased levels of dopamine

4. Impaired blood flow to the brain

The correct answer is: Decreased levels of dopamine

Symptoms of Parkinson's disease primarily stem from the degeneration of dopaminergic neurons in the brain, particularly in a region called the substantia nigra. This loss of neurons leads to decreased levels of dopamine, a neurotransmitter crucial for the regulation of movement and coordination. When dopamine levels drop, patients experience classic symptoms such as tremors, rigidity, bradykinesia (slowness of movement), and postural instability. Understanding the role of dopamine in the basal ganglia circuitry highlights how its reduction disrupts the balance between excitation and inhibition that is necessary for smooth and controlled movements. Therefore, the decreased levels of dopamine are directly linked to the motor and non-motor symptoms commonly associated with Parkinson’s disease, confirming that this is the contributing factor to the condition's symptoms.