Which condition is likely to cause a patient to slur words or speak in a monotone manner?

Parkinson's disease is characterized by a variety of motor symptoms, one of which can significantly affect speech. The condition often leads to bradykinesia, which is a slow movement, and can also cause rigidity in the muscles, affecting how a person articulates words. As a result, patients with Parkinson's may exhibit slurred speech or speak in a monotone voice due to the lack of the ability to modulate pitch and volume. This speech pattern is known as hypophonia, which is common in this population.

While other conditions like multiple sclerosis, stroke, and dementia can also impact speech and communication, the specific nature of Parkinson’s disease tends to uniquely lead to this kind of speech pattern. Each of these other conditions has its own distinct effects on cognitive function and speech, but the monotonal and slurred speech is most prominently tied to the motor control difficulties that arise from Parkinson's disease.