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Chapter 52: Parkinson Disease

What is the primary neurotransmitter deficiency in Parkinson disease?

a. Acetylcholine

b. Dopamine

c. Norepinephrine

d. Serotonin

Answer b is correct. The deficiency is caused by a loss of nigrostriatal neurons in the substantial nigra pars compacta.

Answer a is incorrect. There is a relative overactivity of acetylcholine in Parkinson disease.

Answer c is incorrect. Adrenergic pathways may be affected by Parkinson disease, but norepinephrine is not the primary neurotransmitter deficiency.

Answer d is incorrect. Serotonergic pathways may be affected by Parkinson disease, but serotonin is not the primary neurotransmitter deficiency.

What is the primary goal of Parkinson disease treatment?

a. Cessation of disease progression

b. Facilitating an increase in the storage capacity of dopamine

c. Maintenance of functional ability

d. Reversal of neuronal loss

Answer c is correct. The control of motor symptoms ultimately allows the Parkinson disease patient to continue to function and perform normal activities of daily living. As there is no medication that stops disease progression, the goal is to maintain the patient’s ability to function as long as possible.

Answer a is incorrect. There are currently no therapies that stop the progression of Parkinson disease.

Answer b in incorrect. As Parkinson disease progresses, additional neurons will cease to function and dopamine levels will continue to decrease. As there is no medication that stops disease progression, there is no medication that increases dopamine storage capacity.

Answer d is incorrect. There are no medications capable of reversing the loss of nigrostriatal neurons.

What is the role of carbidopa in the treatment of Parkinson disease?

a. It inhibits acetylcholine.

b. It inhibits dopa decarboxylase.

c. It inhibits catechol-O-methyltransferase.

d. It inhibits monoamine oxidase.

Answer b is correct. Carbidopa inhibits dopa decarboxylase to prevent the conversion of levodopa to dopamine in the periphery allowing the drug to cross the blood–brain barrier.

Answer a is incorrect. Anticholinergics (such as benztropine) inhibit acetylcholine.

Answer c is incorrect. COMT inhibitors (tolcapone and entacapone) inhibit catechol-O-methyltransferase.

Answer d is incorrect. MAO inhibitors (selegiline and rasagiline) inhibit monoamine oxidase.

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