A common medication treatment for Parkinson's disease is levodopa/carbidopa combination medication. The nurse knows that this medication is used because which of the following neurotransmitter is decreased in a person with Parkinson's disease?

A. Delirium is an acute, temporary state of confusion, often caused by factors such as dehydration, infection, or metabolic disturbances. In this case, the elderly client’s confusion following vomiting and not eating or drinking for 2 days suggests that dehydration or an underlying illness is likely causing the delirium.

B. Alzheimer's disease is a progressive, degenerative condition that leads to chronic memory loss and cognitive decline. It does not typically cause sudden confusion, as seen in this case.

C. Huntington's disease is a genetic neurodegenerative disorder that causes motor dysfunction and cognitive decline. It does not present suddenly with confusion in an elderly client.

D. Parkinson's disease is a progressive neurological disorder that primarily affects motor function, causing tremors, rigidity, and bradykinesia. It does not typically present with sudden confusion or the symptoms described in this case.

A. A thrombotic stroke is typically caused by a blood clot that forms in an artery supplying blood to the brain, usually due to atherosclerosis. While it is a possible cause of stroke, it is not the most likely in this patient with atrial fibrillation.

B. A cerebral aneurysm involves a weakness in the blood vessel wall that can lead to rupture and bleeding, causing a hemorrhagic stroke, but this is not the most common type of stroke in patients with atrial fibrillation.

C. Embolic stroke occurs when a clot or other debris (such as a thrombus) breaks off from a distant part of the body (like the heart in atrial fibrillation) and travels to the brain, blocking a cerebral artery. This is the most common type of stroke in patients with atrial fibrillation due to the formation of clots in the left atrium that can embolize to the brain.

D. Hemorrhagic stroke is caused by the rupture of a blood vessel in the brain, leading to bleeding. It is not the most common type of stroke in patients with atrial fibrillation, though it can occur if there is coagulopathy or anticoagulant therapy.