Parkinson’s is a progressive neurological disease. People with Parkinson’s experience various physical, cognitive, and psychological symptoms. Often, the early symptoms of Parkinson’s are so subtle that the disease goes unnoticed for years. As the disease progresses, a lack of motor skills becomes more apparent. This is followed by cognitive impairments, including trouble following directions and loss of thought.

Doctors look for early evidence of non-motor or pre-motor symptoms long before motor symptoms appear. According to neurologist Dr. Lawrence Severt, the following non-motor symptoms may be early indicators of Parkinson’s:

  • a diminished sense of smell
  • a long history of constipation
  • REM-sleep behavior disorder
  • a history of anxiety and depression

Other non-motor symptoms may include:

  • speaking in a low-volume voice
  • changes in speech
  • difficulty finding words
  • low blood pressure when standing
  • painful foot cramps
  • changes in personality
  • problems with skin
  • drooling
  • increased sweating
  • increased urination urgency
  • increased urination frequency
  • erectile dysfunction

Parkinson’s disease is primarily a movement disorder. It reduces the amount of dopamine in the brain. Nerve cells use dopamine to send messages that control muscle movement. A brain that’s low in dopamine has less control over muscle function. That lack of control leads to motor symptoms that affect movement.

The four main motor symptoms include:

  • tremor
  • muscle rigidity
  • bradykinesia (slow movement)
  • poor balance or posture that may affect walking

Not everyone will have all the main motor symptoms. Similar symptoms are also common in other neurological disorders.

Motor symptoms may begin on just one side of the body at first and progress to both sides as the disease worsens. Additional motor symptoms may include the following:

  • loss of automatic movements, such as smiling and blinking
  • “masked” face, or a lack of expression
  • shuffling gait
  • trouble rising from a seated position
  • difficulty swallowing or eating
  • stooped posture
  • impaired balance
  • decreased arm swinging when walking
  • small handwriting
  • freezing, or walking in quick small steps
  • trouble moving or turning in bed
  • slowed daily activities
  • staying in the same position for long periods

Also, many motor symptoms of Parkinson’s are associated with vision. These symptoms relate to the muscle movements of the eyeball. Vision-related symptoms include:

  • trouble focusing
  • trouble opening the eyes
  • blurred vision
  • eyestrain
  • chronic dry eye
  • eyelid spasms
  • excessive blinking

In addition to vision changes, people with Parkinson’s often have significant cognitive impairments. Sometimes those changes interfere with thinking. Common symptoms include problems with memory and difficulty paying attention or solving problems. Some of those changes may be less obvious because they occur gradually.

Cognitive symptoms are usually more noticeable in the later stages of the disease. If they’re discovered early, they’re typically confined to specific domains of brain function. Here are examples of specific domains influenced by decreasing dopamine:

  • Executive functions: People with Parkinson’s may have trouble making plans or reaching goals. It may also be more difficult for them to anticipate the consequences of their actions.
  • Slowed thinking: Typical daily tasks are challenging for people with Parkinson’s. Problems are more difficult to solve and following directions is more difficult. People with Parkinson’s also sometimes have trouble accessing specific words.
  • Impaired memory: Those with Parkinson’s often have difficulty remembering, storing, and accessing information.
  • Difficulty paying attention: People with Parkinson’s often find it difficult to follow complex scenarios. For example, they have may trouble understanding a multi-person conversation.
  • Impaired understanding of spatial relationships: Parkinson’s may impair people’s ability to determine where they are in space in relation to everything else. That impairment may affect their ability to operate a moving vehicle.

It’s not uncommon for cognitive symptoms to include elements of dementia, confusion, depression, anxiety, and even hallucinations.

Parkinson’s disease is categorized in five stages. But everyone progresses through the disease differently and at different rates. This is especially true as advancements in treatment slow its course. These treatments include medication, surgery, and lifestyle changes.