Handedness and dominant side of symptoms in Parkinson's disease.

The aim of this retrospective study was to assess the presence of a possible association between handedness and the side of symptom dominance in 963 patients with Parkinson's disease (PD). In only 287 patients the hand dominance was registered. Out of 254 right-handed patients, 158 (62%) had a right-side dominance of PD symptoms, while 96 patients (38%) had left-lateralized symptom dominance (p < 0.001). For the 33 left-handed subjects, 18 (55%) had left- and 15 (45%) had right-sided symptom dominance (p = 0.602). Right-handedness thus appeared to be associated with right-sided dominance of PD symptoms, while the group of left-handed patients was too small to draw conclusions from. Possible explanations are discussed.