Can anxiety increase tremors in patients with Parkinson’s disease? An experimental model

Abstract Background Among non-motor symptoms of Parkinson’s disease (PD), anxiety occurs in up to 67% of patients. Clinically, PD patients report worsening of tremors in anxiogenic situations. Objective The aim of this study was to evaluate the association between motor symptoms and anxiety in PD patients and compare their performances with those of healthy volunteers. Methods Fifteen volunteers with PD and 15 healthy volunteers without clinically significant psychiatric disorders were evaluated. Both groups were subjected to a simulated public speaking test (SPST). The following parameters were measured: visual analog mood scale (VAMS), items related to tremors of UPDRS, bradykinesia tests, blood pressure, and heart rate. Results Results of repeated measures ANOVA indicated a significant effect on group × phase interaction (F3.7,105.6 = 2.56; p = 0.046) for VAMS anxiety factor. Regarding tremors, ANOVA indicated significant differences in group × phase interaction (F4.5,121 = 2.88; p = 0.021) and between the groups (F1,27 = 45.88, p < 0.001), with differences in the anticipatory phase, performance, and post-speech, compared with those in the baseline. There were no significant differences between the groups with regard to other factors of VAMS, physiological measurements, and bradykinesia. Discussion Worsening of tremors occurred during SPST, particularly in phases with higher anxiety scores.