A right-handed 73-year-old male presents to your GP with his wife. He complains of a 6-month history of tremor in his right hand at rest. The wife noticed the tremor disappears completely during his sleep. The tremor is more noticeable when he is writing and his writing is smaller than it used to be. She also reports he has difficulty changing his position at night, and often kicks her during sleep whilst sleeping. Upon further questioning, he reports often feeling a little woozy, particularly when getting out of bed in the morning and resolves spontaneously. On examination, he has a slow shuffling gait with difficulty starting, stopping or turning. His face has minimal expression and his voice is rather soft. His tone is increased in both the upper and lower limbs with notable cog wheeling at his wrists. Which of the following features are less commonly seen in patients with PD?