Language, speech, and communication disorders in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder, which mostly afflicts older people, affecting the motor, executive, and neuropsychological functions of an individual. 89% of the patients suffer from language and speech disorders and only 3% of them receive treatment. In general, patients' speech is quieter, their voices are harsh and breathy, the intonation is flat, and the articulation is imprecise, which makes communication difficult and significantly affects the patients' life. This article discusses language, speech, and communication disorders in PD, including their articulatory, respiratory, acoustic, and pragmatic aspects. Among the most common disorders are hypokinetic dysarthria, palilalia, phonatory impairment, long pauses, metaphor understanding and contrastive stress problems, impaired sentence processing, turn-taking, staying on topic and others. Possible ways of treatment are then presented (pharmacological, stereotactic, and behavioural therapy), with a special focus on Lee Silverman Voice Treatment (LSVT), a behavioural treatment programme in which the goal is to make the patients speak louder and to re-calibrate their perception of loudness. Normally a patient receives 13-16 hours of individual therapy during one-hour sessions four times a week in one month. In an extended version (LSVT-X) the one-hour sessions take place twice a week over two months. An increasing body of evidence indicates the efficacy of LSVT. The Polish version of LSVT Virtual Therapist (LSVTVT) has also shown significant improvement in linguistic functions.