Parkinson’s disease is a progressive neurological disorder that damages the central nervous system. The condition affects mainly adults over the age of 65. It’s estimated that nearly two percent of adults, or about 1 million Americans, in that age range have Parkinson’s disease.

Of those people, as many as 20 percent may develop Parkinson’s disease dementia, a decline in thinking, reasoning, and problem-solving caused by Parkinson’s disease. (Some estimates put the prevalence as high as 80 percent.) Patients with Parkinson’s disease are six times more likely to develop dementia than people their same age who do not have Parkinson’s disease. According to the Alzheimer’s Association, the average time from onset of Parkinson’s disease to diagnosis of Parkinson’s dementia is 10 years.

What are the symptoms of Parkinson’s disease dementia?

The most common symptoms of Parkinson’s disease dementia include:

  • appetite changes
  • changes in energy levels
  • confusion
  • delusions, paranoid ideas, and hallucinations
  • depression
  • difficulty with memory recall and forgetfulness
  • inability to concentrate
  • inability to apply reasoning and judgment
  • increased anxiety
  • mood swings
  • loss of interest
  • slurred speech
  • sleep disturbances

How is Parkinson’s disease dementia diagnosed?

Diagnosis of Parkinson’s disease has no single test, and Parkinson’s disease dementia doesn’t either. Instead, doctors rely on a series or combination of tests and indictors to determine if a Parkinson’s disease patient has developed dementia.

A neurologist will likely diagnose you and track your progression after you have been diagnosed with Parkinson’s disease. Your neurologist may monitor you for signs that suggest you’re developing dementia. As you get older, your risk for Parkinson’s disease dementia increases, so your doctor is more likely to conduct regular testing to monitor your cognitive functions, memory recall, and mental health.

What causes Parkinson’s disease dementia?

The nerve cells in an average brain use dopamine, a neurotransmitter, to control and coordinate muscle movement. Over time, Parkinson’s disease destroys the nerve cells that make dopamine. Without this chemical messenger, the nerve cells cannot properly relay instructions to the body, and you will suffer loss of muscle function and coordination. Why these brain cells disappear is not understood.

Parkinson’s disease also causes dramatic changes in a part of your brain that controls movement. Patients with Parkinson’s disease often experience motor symptoms as a preliminary sign of the condition—tremors are one of the most common first symptoms of Parkinson’s disease. As the disease progresses and spreads in your brain, it can begin to affect the parts of your brain responsible for mental functions, memory, and judgment. Over time, your brain may not be able to use these areas of your brain as efficiently as it once did, and you may begin experiencing symptoms of Parkinson’s disease dementia.

What risk factors increase a person’s chance of developing Parkinson’s disease dementia?

The following factors increase your risk of developing Parkinson’s disease dementia:

  • You are male.
  • You are older. As you age, your risk for Parkinson’s disease dementia increases.
  • You have existing mild cognitive impairment.
  • You have more severe symptoms of motor impairment. Patients with greater and more pronounced motor symptoms, such as rigidity and gait disturbance, are more likely to develop Parkinson’s disease dementia.
  • You have been diagnosed with psychiatric symptoms related to Parkinson’s disease, such as depression.

How is Parkinson’s disease dementia treated?

No single drug or treatment can cure Parkinson’s disease dementia. Currently, doctors focus on prescribing a treatment plan that can help treat the symptoms of Parkinson’s disease. Some of these drugs, however, can make dementia and related mental symptoms worse.

Before you meet with your doctor

If you are aware of increasing symptoms of Parkinson’s disease dementia, start a journal or diary and record what you’re experiencing, when symptoms occur, how long they last, and if medicine helped in any way. If you are a caregiver or a loved one caring for a patient with Parkinson’s disease, keep a journal for your loved one. Record the symptoms they experience, how often it occurs, and any other relevant information. Present this journal to your neurologist at your next appointment to see if the symptoms are related to Parkinson’s disease dementia or possibly another condition.