The effects of medication on turning in people with Parkinson disease with and without freezing of gait.

Turning difficulty is prevalent in Parkinson disease (PD) and may lead to falls or freezing. Medication improves motor symptoms of PD, but its effects on turning in people with PD with (PD+FOG) and without (PD-FOG) freezing of gait are unclear. This study evaluated the effects of medication on turning in PD compared to healthy older adults (controls), and in PD+FOG compared to PD-FOG. We assessed timed-up-and-go (TUG), and in-place turns in 16 controls and 20 people with PD (10 PD+FOG, 10 PD-FOG) OFF and ON medication. PD+FOG performed worse than PD-FOG (p < 0.05) in TUG, turn duration, step count, and had earlier head rotation onset (HTO). These measures improved ON medication in PD+FOG and PD-FOG (p < 0.05). Turn duration and step count improved more with medication in PD+FOG than PD-FOG (p < 0.005). There were subtle differences in gastrocnemius and sternocleidomastoid onsets, with PD OFF or ON activating muscles earlier than controls. Tibialis anterior, gastrocnemius, and sternocleidomastoid initial onset times were similar between PD+FOG and PD-FOG. Though medication improved turning, turn duration and step count impairments still existed in PD ON, compared to controls. Relative to PD-FOG, PD+FOG turned worse, but improved more with medication, potentially because PD+FOG were initially more impaired than PD-FOG or were taking higher medication dosages. Further treatment options may be needed to address ON medication turning deficits.