An Overview of Parkinson's Dementia

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Parkinson's dementia is a form of dementia typically diagnosed in someone years after being diagnosed with Parkinson's disease. This type of dementia is often difficult to diagnose and causes motor and cognitive symptoms that impact the individual's ability to accomplish daily tasks.

The characteristics of Parkinson's dementia distinguish it from other diseases associated with dementia. People with this type of dementia deal with motor impairments—slowed movement and trouble moving, tremors while at rest, and unstable walking—and difficulty thinking and reasoning, such as memory loss, shortened attention span, and difficulty finding words.

This article discusses Parkinson's dementia symptoms, causes, diagnosis, and treatment.

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A person with dementia deals with changes in memory, thinking, and reasoning, which leads to difficulties in accomplishing daily activities and diminished quality of life. With Parkinson’s disease dementia (PDD), or Parkinson’s dementia, symptoms of dementia are always accompanied by a decline in movement ability.

Parkinson’s disease starts with changes in the brain occurring in areas important for the control of motor functions. These changes can cause symptoms like stooped posture, resting tremors, shakiness, difficulty in initiating movement, and shuffling steps. As these changes continue, cognitive functions and memory may also become affected, leading to the diagnosis of PDD.

Unlike other diseases that have associated dementia, like Alzheimer’s disease, Parkinson’s dementia does not happen to everyone diagnosed with Parkinson’s disease.

People diagnosed with Parkinson’s dementia can experience a variety of symptoms, which often change over time. These symptoms often overlap with symptoms of Parkinson’s disease.

Symptoms patients report include:

  • Trouble concentrating and learning new material
  • Changes in memory
  • Episodes of paranoia and delusions
  • Confusion and disorientation
  • Mood changes, like irritability
  • Depression and anxiety
  • Hallucinations
  • Muffled speech

Affected people also have trouble interpreting visual information, as well as problems with sleep connected to sleep disorders, like REM behavior disorder or excessive daytime sleepiness.


Researchers do not fully understand how changes in the structure and chemistry of the brain leads to Parkinson’s disease and possible dementia. Nevertheless, there are several factors that are commonly present at the diagnosis of Parkinson’s disease that increase the likelihood of developing dementia.

One major change that happens in the brain in someone diagnosed with Parkinson’s disease and Parkinson’s dementia is the development of unusual microscopic deposits called Lewy bodies. These deposits are primarily made of a protein that is normally found in a healthy, active brain called alpha-synuclein. Lewy bodies are also found in other brain disorders, like Lewy body dementia.

Another change in the brain that occurs in Parkinson’s dementia is the presence of plaques and tangles. Plaques and tangles are also protein fragments that build up in the brain, either in between nerve cells (plaques) or within cells (tangles). Like Lewy bodies, the presence of these protein deposits is also found in Lewy body dementia.

Factors that might put someone at a higher risk for developing Parkinson’s dementia are the following:

  • Advanced stage in Parkinson’s disease
  • Family history of dementia
  • Severe motor symptoms
  • Mild cognitive impairment
  • History of hallucinations
  • Chronic daytime sleepiness
  • Unstable posture, difficulty initiating movements, shuffling steps, and/or problems with balance and completing full movements.

Men and people of older ages tend to be at a higher risk for Parkinson’s dementia.


While Parkinson’s disease is fairly common, affecting 1% to 2% of people over the age of 60, Parkinson’s dementia is not as common. Not every person diagnosed with Parkinson’s disease develops Parkinson’s dementia. In fact, 30% of people diagnosed with Parkinson’s disease do not develop Parkinson’s dementia. According to recent studies, 50% to 80% of people diagnosed with Parkinson’s disease may develop Parkinson’s dementia.

Developing Parkinson’s dementia is very dependent on the stage of Parkinson’s disease. Usually, people with Parkinson’s disease begin to develop movement symptoms between ages 50 and 85, and the average time for dementia to develop after diagnosis is 10 years.

Dementia does contribute to increasing the likelihood of dying from Parkinson’s disease. A person diagnosed with Parkinson’s dementia can live for several years after diagnosis, on average, up to 5 to 7 years.


Diagnosing Parkinson’s disease is not easy and requires a careful clinical evaluation by a neurologist and sometimes additional tests. The Movement Disorder Society (MDS) Task Force came up with four-part guidelines for diagnosing Parkinson’s dementia. These include:

  • Looking at core features
  • Evaluating associated clinical features
  • Evaluating the presence of features which might make the diagnosis uncertain
  • Assessing if there are features present that might make the diagnosis impossible

One key factor for the diagnosis of Parkinson’s dementia is that the patient must have been diagnosed with Parkinson’s disease for at least a year before the development of dementia.

If dementia appears before a year after being diagnosed with Parkinson’s disease, it is considered dementia with Lewy bodies or Lewy body dementia (LBD). Additionally, LBD is diagnosed, as opposed to Parkinson’s dementia, if dementia appears before or within a year of movement symptoms.


Unfortunately, there is currently no way of stopping or slowing down the progression of Parkinson’s dementia and Parkinson’s disease. Talking with your healthcare provider or a specialist, like a neurologist or movement disorders specialist, may help to develop ways to manage symptoms.

Management plans for Parkinson’s dementia can be through a variety of ways, such as counseling, therapy, and even medications. If your management plans include medications, work closely with your healthcare provider to determine which medications and what dosage will be best for improving your symptoms and avoiding side effects. Often times, people diagnosed with Parkinson’s disease are more sensitive to medications.


Two common medication options for people diagnosed with Parkinson’s dementia are cholinesterase inhibitors and antipsychotic drugs. These drugs are usually prescribed to those diagnosed with Alzheimer’s disease.

Cholinesterase inhibitors are usually used to treat changes in thinking and behavior, and may help someone with Parkinson’s dementia in reducing symptoms of visual hallucinations, memory, and changes in sleep patterns.

Cholinesterase inhibitors include:

  • Donepezil
  • Rivastigmine
  • Galantamine

Although cholinesterase inhibitors might help in reducing hallucinations, these medications might actually worsen movement symptoms. Noticing as a hallucination begins, and switching the topic, can be a helpful alternative to avoid any frustrations associated with hallucinating.

Antipsychotic drugs are usually prescribed to treat behavioral symptoms. Unfortunately, these medications may cause serious side effects in nearly 50% of patients with Parkinson’s dementia. Side effects from antipsychotic drugs include:

  • Worsening Parkinson’s symptoms
  • Delusions
  • Hallucinations
  • Abrupt changes in consciousness
  • Trouble swallowing
  • Acute confusion

Other drugs a healthcare provider might prescribe to patients with Parkinson’s dementia depends on their unique set of symptoms. If the patient is dealing with depression, selective serotonin reuptake inhibitors (SSRIs), common antidepressants, may be used as treatment. If the patient is having trouble sleeping, sleep medications, like melatonin, may be recommended.

Aside from taking medications, it is important to stop taking medications that might impair cognition.

Routines and Therapies

With some patients diagnosed with Parkinson’s dementia, they might show signs of difficulty understanding the natural day-night cycle. Keeping a consistent daily routine can be beneficial and may help lend some guidance.

  • Set bedtime at the same hour every day and increase darkness by closing the window blinds and turning off the lights. This will help signal to both the brain and the individual that it is time for sleep.
  • Avoid napping in the day and spend time physically active and in daylight.
  • Indicators of time, like calendars and clocks, should be present to help reorient the affected person to the day-night cycle.

While there are several options for managing cognitive and behavioral symptoms, movement symptoms are a bit more challenging to manage in patients with Parkinson’s dementia. The most common treatment option available, carbidopa-levodopa, has actually been found to increase symptoms of hallucinations and aggravation in patients.

Deep brain stimulation (DBS) for PDD is being explored in clinical trials. So far, the studies are small and do not have consistently positive results.

Physical therapy may also be beneficial in relieving movement symptoms and regaining strength and flexibility in stiff muscles.

Other options to consider include:

  • Speech therapy to aid communication
  • Regular exercise
  • Eating a balanced diet
  • Getting adequate sleep
  • Managing other illnesses that might impact brain health, like diabetes, sleep apnea, or high cholesterol

Tips for Caregivers

As dementia progresses and hallucinations and behaviors alter, more difficulties may arise for caregivers. Patients with Parkinson’s dementia may be disoriented, predisposed to impulsive behavior, experience sudden changes in mood, and may need help with accomplishing daily tasks.

Use the following strategies to help manage the patient’s dementia and calm them down:

  1. Develop a well-structured routine and schedule.
  2. Keep the environment safe and simply decorated to help minimize distraction or the chance for confusion.
  3. Stay calm and express care and affection when communicating.
  4. Use a nightlight to reduce the chance for hallucinations exacerbated by visual impairment at night.
  5. Remember that the behavioral and cognitive changes are due to the disease, rather than the individual themselves.
  6. With any hospitalization or after a surgical procedure, be very observant. A person with Parkinson’s dementia can become severely confused following the procedure.
  7. Pay close attention to medication sensitivities.

These efforts may reduce the stress on the caregiver and optimize the well-being of the affected person.

A Word From Verywell

If you or your loved one has been diagnosed with Parkinson’s dementia, you are not alone. Despite this form of dementia not always developing in those with Parkinson’s disease, it is not uncommon and can require adjustments in the life of the person diagnosed and their loved ones.

Resources like the Michael J. Fox Foundation for Parkinson’s Research, Family Caregiver Alliance, and the Parkinson’s Foundation can help keep you updated with research and information.

If you have more questions regarding Parkinson’s dementia and managing symptoms, schedule an appointment to talk with your healthcare provider, with a neurologist, or with a movement disorders specialist.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Parkinson’s Foundation. Parkinson’s dementia fact sheet.

  2. Alzheimer’s Association. Parkinson’s disease dementia.

  3. National Institute of Neurological Disorders and Stroke. Parkinson's disease: Hope through research.

  4. American Parkinson Disease Association. Sleep problems.

  5. UCSF Memory and Aging Center. Parkinson’s disease dementia.

  6. Emre M, Aarsland D, Brown R, et al. Clinical diagnostic criteria for dementia associated with Parkinson's disease. Mov Disord. 2007;22(12):1689-707. doi:10.1002/mds.21507

  7. Poewe W, Gauthier S, Aarsland D. Diagnosis and management of Parkinson’s disease dementia. Int J Clin Pract. 2008 Oct;62(10):1581-1587. doi:10.1111/j.1742-1241.2008.01869.x

  8. Goldman JG, Holden S. Treatment of psychosis and dementia in Parkinson's diseaseCurr Treat Options Neurol. 2014;16(3):281. doi:10.1007/s11940-013-0281-2

  9. Lv Q, Du A, Wei W, Li Y, Liu G, Wang XP. Deep brain stimulation: A potential treatment for dementia in Alzheimer's disease (AD) and Parkinson's disease dementia (PDD)Front Neurosci. 2018;12:360. doi:10.3389/fnins.2018.00360

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.