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A new technique utilizes voice analysis to assist in the early diagnosis of Parkinson's disease. The technique can distinguish speech changes in individuals with Parkinson's from the speech of healthy individuals [Journal of Speech, Language, and Hearing Research, 53: 114-25].
"Early diagnosis is immeasurably important when dealing with Parkinson's disease," said Shimon Sapir, PhD, a professor in the Department of Communication Sciences and Disorders at the University of Haifa who developed the technique. "This is a non-invasive, reliable and accurate technique that only requires the patient to read out a few simple sentences."
Researchers at Haifa studied the technique alongside U.S. scientists with funding from the National Institutes of Health (NIH).
Parkinson's affects the muscles controlling voice and speech in most patients. Existing acoustic tests do not pick up significant differences between the speech articulation of individuals with early Parkinson's and that of healthy individuals, even when the differences are already noticeable to the listener.
"This failure to detect acoustic differences has to do with the relatively large differences between speakers' speech signals, which is mainly due to anatomical differences between speakers," Dr. Sapir suggested. The method he developed minimizes the effects of speaker variability and maximizes the sensitivity of the acoustic analysis to true differences between the speech of individuals with Parkinson's and that of healthy speakers.
He and his colleagues tested the utility of the acoustic analysis method. One study tested two groups: a group of individuals with Parkinson's and another group of healthy individuals. The participants recorded a number of sentences which were then put through acoustic analysis with the program that was designed for this particular purpose. The system was able to make a clear differentiation between the two groups of participants. In another study the speech of individuals with Parkinson's at stages I and II of the disease was compared to the speech of healthy individuals. At this stage of the study, too, the system was able to distinguish the Parkinson's group from the healthy group.
An additional study applied the acoustic method to compare the speech of individuals with Parkinson's before and after successful behavioral speech therapy. The results showed that the analysis system was sensitive to changes that occurred in those patients who had undergone therapy for speech.
Importantly, scientists in Germany who used Dr. Sapir's method also have reported revealing significant differences between speakers with early stages of Parkinson's and healthy speakers with normal speech. Collectively, these findings indicate that the method developed by Dr. Sapir not only enables early diagnosis of the disease but makes it possible to track changes in patients that may occur in response to treatment or as the disease progresses.
"Doctors and scientists agree that early diagnosis of Parkinson's is important in order to slow down or even prevent the degenerative progress of this disease," Dr. Sapir explained. "Today, no treatment is available to this effect; but when treatment becomes feasible, early diagnosis is going to be crucial. There are various methods of brain imaging for detecting early signs of Parkinson's, but these methods are expensive, particularly when attempting to screen a large population at risk. Hence, the importance of developing techniques for early diagnosis that are valid, reliable, non-invasive, simple, readily available and inexpensive."
While the initial results are encouraging, additional studies must be carried out to examine the new method, he stressed. "Also, given that the disease and its progression have different effects on individuals, speech analysis must be incorporated into a battery of tests that examine other signs and symptoms of the disease, such as changes in handwriting, cognitive functions, sense of smell, and more."
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