Parkinson disease is considered a progressive disorder because it changes with time; its initial symptoms may worsen and new symptoms may appear.
The new symptoms may include postural hypotension (a drop in blood pressure on sitting or standing), freezing of gait (FOG), falls, swallowing difficulty, and weight loss.
The new symptoms may include anxiety, depression, and forgetfulness. Some of these symptoms result from the drugs used to treat PD, but most result from PD. The earliest symptoms of PD can be so subtle and vague as to be dismissed or taken for something else.
When you look back you can see that symptoms you thought were related to aging were actually part of PD. When PD begins, usually only one side is affected and, as PD progresses, the other side is involved.
Often, you are aware of the symptoms, but don’t think anything is wrong—it may be your spouse who insists there is a change.
PD affects the basal ganglia, which are situated at the base of the brain between the cortex (the thinking brain) and the brainstem and spinal cord (the parts controlling movement).
The cortex specifies the speed, amplitude, and duration of movement. The basal ganglia translate these commands into movements that occur without your awareness of them, movements such as swinging your arms while walking.
Because the movements are automatic, many PD patients do not realize they are slowed. The basal ganglia function like both the accelerator and brake in a car. The substantia nigra, putamen, and caudate nucleus comprise the accelerator; the “gasoline” is dopamine; and the globus pallidus, subthalamic nucleus, and thalamus comprise the brakes.
In PD, not only is your accelerator defective, resulting in slowing down, but it is as though your brakes are always on, thus slowing you down even further.