My dad (Ian) began losing his balance/falling backwards, if you didn't know better you would think he had been drinking as would stumble/sway when he walked and slurred his words at times. Another family member actually asked if he did have a drinking problem after seeing him one day.
The main problems are the stumbling/falling, often his top half moves faster than his feet. At one point we had visited A&E each month on the trot for 3 months with head injuries from falling backwards down the stairs.
He often complains of feeling dizzy/light headed, and of having headaches/stiff neck.
In the summer of 2018 he has also been diagnosed with Dementia Associated with PSP.