What therapeutic outcome is expected for a client with Parkinson's disease taking diphenhydramine?

In individuals with Parkinson's disease, diphenhydramine, an antihistamine with anticholinergic properties, is sometimes used off-label to help manage symptoms such as tremors. While it does not address the underlying pathology of Parkinson's disease or provide a disease-modifying effect, diphenhydramine can temporarily relieve some motor symptoms associated with the condition, including tremors. Its ability to reduce the activity of acetylcholine can help improve control over involuntary muscle movements, which is a hallmark symptom of Parkinson's disease.

The other options do not align with the expected outcomes of diphenhydramine for a client with Parkinson's disease. For instance, there is no evidence that diphenhydramine can delay disease progression; it primarily addresses symptomatic relief. Improved bladder function is not a recognized effect of diphenhydramine in the context of Parkinson's disease treatment. Similarly, while managing depression may be important for these patients, diphenhydramine is not indicated as an antidepressant and thus would not be expected to provide relief of depression. Therefore, the most appropriate therapeutic outcome from the use of diphenhydramine in this scenario is decreased tremors.