The standard Parkinson's drugs don't always work well for speech impairment. Although some people find that levodopa improves their communication, others don't. Deep brain-stimulation surgery has also produced inconsistent results for relieving speech difficulties.

The best strategy is drug therapy paired with speech therapy. Traditionally, speech-language experts trained patients to concentrate on multiple, separate aspects of voice and speech, such as breathing properly, articulating well, increasing volume, and slowing down the rate of speech. But even though patients sounded better inside the treatment room, the benefit typically vanished once they walked out the door and reverted to usual habits.

In 1987, however, University of Colorado speech-language researcher Lorraine Olson Ramig devised the Lee Silverman Voice Treatment, the first speech treatment tailored for Parkinson's disease. (It was named after a Parkinson's patient whose family funded the research). Small studies have found that LSVT produces lasting improvements.

How LSVT differs from traditional speech treatments:

• LSVT is much more intensive, requiring four rigorous one-hour sessions a week -- and daily voice homework exercises -- for one month.
• It attempts to overcome the sensory processing deficit that affects speech in Parkinson's. For example, by recording patients' voices and playing them aloud, the therapist can convince them before treatment that their voices are weak.
• A patient focuses on a single goal -- boosting loudness with maximal effort -- rather than thinking about several aspects of voice and speech production at once.