Although speech dysfluencies have been hypothesized to be associated with abnormal function of dopaminergic system, the effects of dopaminergic medication on speech fluency in Parkinson's disease (PD) have not been systematically studied. The aim of the present study was, therefore, to investigate the long-term effect of dopaminergic medication on speech fluency in PD. Fourteen de novo PD patients with no history of developmental stuttering and 14 age- and sex-matched healthy controls (HC) were recruited. PD subjects were examined three times; before the initiation of dopaminergic treatment and twice in following 6 years. The percentage of dysfluent words was calculated from reading passage and monolog. The amount of medication was expressed by cumulative doses of L-dopa equivalent. After 3-6 years of dopaminergic therapy, PD patients exhibited significantly more dysfluent events compared to healthy subjects as well as to their own speech performance before the introduction of dopaminergic therapy (p < 0.05). In addition, we found a strong positive correlation between the increased occurrence of dysfluent words and the total cumulative dose of L-dopa equivalent (r = 0.75, p = 0.002). Our findings indicate an adverse effect of prolonged dopaminergic therapy contributing to the development of stuttering-like dysfluencies in PD. These findings may have important implication in clinical practice, where speech fluency should be taken into account to optimize dopaminergic therapy.

Department of Circuit Theory Faculty of Electrical Engineering Czech Technical University Prague Technická 2 166 27 Prague 6 Czech Republic

Zobrazit více v PubMed

J Neurol Neurosurg Psychiatry. 1992 Mar;55(3):181-4 PubMed

Expert Opin Pharmacother. 2004 Jul;5(7):1565-71 PubMed

J Speech Lang Hear Res. 2003 Aug;46(4):1009-15 PubMed

Neuroreport. 1997 Feb 10;8(3):767-70 PubMed

J Speech Hear Disord. 1978 Feb;43(1):47-57 PubMed

Brain Lang. 2013 Sep;126(3):263-78 PubMed

Folia Phoniatr Logop. 2011;63(4):187-94 PubMed

PLoS One. 2012;7(2):e32132 PubMed

Mov Disord. 2001 Jan;16(1):114-8 PubMed

Am J Psychiatry. 1991 Oct;148(10):1309-16 PubMed

J Acoust Soc Am. 2013 Sep;134(3):2171-81 PubMed

J Commun Disord. 2004 Jul-Aug;37(4):325-69 PubMed

J Speech Lang Hear Res. 2007 Aug;50(4):899-912 PubMed

Neuroscience. 2006 Apr 28;139(1):263-76 PubMed

J Neurol Neurosurg Psychiatry. 1989 Jun;52(6):805-7 PubMed

Brain Res. 1987 Aug 25;418(2):262-72 PubMed

N Engl J Med. 2006 Aug 31;355(9):896-908 PubMed

J Neural Transm (Vienna). 2006 May;113(5):625-31 PubMed

Brain. 2008 Jan;131(Pt 1):50-9 PubMed

Brain Lang. 2008 Feb;104(2):190-9 PubMed

Curr Opin Otolaryngol Head Neck Surg. 2008 Jun;16(3):205-10 PubMed

Mov Disord. 2012 Jan;27(1):8-30 PubMed

Mov Disord. 2001 May;16(3):562-5 PubMed

J Fluency Disord. 2003 Spring;28(1):55-70 PubMed

J Acoust Soc Am. 2011 Jan;129(1):350-67 PubMed

J Neural Transm (Vienna). 2009 Feb;116(2):167-9 PubMed

Parkinsonism Relat Disord. 2013 Mar;19(3):383-4 PubMed

J Neurol Neurosurg Psychiatry. 1999 Jun;66(6):776-8 PubMed

Arch Neurol. 1983 Mar;40(3):175-7 PubMed

J Commun Disord. 1996 Nov-Dec;29(6):471-7; quiz 477-8 PubMed

Mov Disord. 2008 Mar 15;23(4):574-80 PubMed

Short-term effects of transcranial direct current stimulation on motor speech in Parkinson's disease: a pilot study

Speech and gait abnormalities in motor subtypes of de-novo Parkinson's disease

Speech disorders in Parkinson's disease: early diagnostics and effects of medication and brain stimulation

Effects of dopaminergic replacement therapy on motor speech disorders in Parkinson's disease: longitudinal follow-up study on previously untreated patients

Speech disorders reflect differing pathophysiology in Parkinson's disease, progressive supranuclear palsy and multiple system atrophy