Speech and gait in Parkinson's disease: When rhythm matters

Speech disturbances in Parkinson's disease (PD) are heterogeneous, ranging from hypokinetic to hyperkinetic types. Repetitive speech disorder has been demonstrated in more advanced disease stages and has been considered the speech equivalent of freezing of gait (FOG). We aimed to verify a possible relationship between speech and FOG in patients with PD.

Forty-three consecutive PD patients and 20 healthy control subjects underwent standardized speech evaluation using the Italian version of the Dysarthria Profile (DP), for its motor component, and subsets of the Battery for the Analysis of the Aphasic Deficit (BADA), for its procedural component. DP is a scale composed of 7 sub-sections assessing different features of speech; the rate/prosody section of DP includes items investigating the presence of repetitive speech disorder. Severity of FOG was evaluated with the new freezing of gait questionnaire (NFGQ).

PD patients performed worse at DP and BADA compared to healthy controls; patients with FOG or with Hoehn-Yahr >2 reported lower scores in the articulation, intellibility, rate/prosody sections of DP and in the semantic verbal fluency test. Logistic regression analysis showed that only age and rate/prosody scores were significantly associated to FOG in PD. Multiple regression analysis showed that only the severity of FOG was associated to rate/prosody score.

Our data demonstrate that repetitive speech disorder is related to FOG and is associated to advanced disease stages and independent of disease duration. Speech dysfluency represents a disorder of motor speech control, possibly sharing pathophysiological mechanisms with FOG.