Parkinson’s disease dementia refers to the symptoms of Parkinson’s that impair thought processes, mental function, and memory.

Parkinson’s disease (PD) is a progressive nervous system disease that can affect a person’s mobility and cognitive ability.

The disease damages the nerve cells producing dopamine in the substantia nigra, an area of the brain. Dopamine is a chemical in the brain that has several functions, including assisting in the coordinated movement of muscles.

In this article, we look at the symptoms, causes, and management of PD dementia.

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Parkinson’s disease dementia can involve a range of cognitive symptoms, including:

Comparison with other dementias

Dementia results from physical changes in the brain that can lead to memory loss and an inability to think clearly. PD dementia has different symptoms from other types.

Alzheimer’s dementia, for example, impairs memory and language. PD dementia, conversely, affects problem-solving, the speed at which thoughts occur, memory, mood, and other critical cognitive functions.

Lewy body dementia and Parkinson’s disease dementia are similar in that Lewy bodies might be present in both forms. Lewy bodies are abnormal protein deposits in the brain that affect function.

While both conditions relate to Lewy bodies, researchers believe how they form in Parkinson’s disease dementia differs from those in Lewy body dementia.

Other types of dementia include:

PD is idiopathic, meaning a doctor does not know why a person has the condition.

However, researchers have identified several risk factors that may make a person with Parkinson’s disease more likely to experience dementia.

These risk factors include:

  • advanced age at the time of diagnosis
  • experiencing excessive daytime sleepiness
  • hallucinations before the onset of other dementia symptoms
  • a history of mild thought impairment
  • more severe movement impairment symptoms than most people with Parkinson’s disease

However, researchers do not know why some people with Parkinson’s disease develop cognitive difficulties and movement problems.


The average progression of time from Parkinson’s diagnosis to the development of dementia is 10 years. However, the long-term progression of Parkinson’s dementia will always differ between people.

PD dementia can reduce a person’s ability to live independently. Advanced stages can affect communication, the ability to understand spoken language, memory, and concentration.

A person will most often receive a diagnosis of PD before any dementia symptoms start. They are more likely to develop mobility problems before any disruption to thought processes.

If a person presents with these symptoms, a doctor should monitor them for movement and cognitive changes.

An individual with a PD diagnosis should notify their doctor if they experience any of the following symptoms:

Some of these symptoms might be side effects of PD medications, but a person experiencing any of these should notify their doctor to rule out possible dementia.

Diagnosing dementia can be difficult, as no single test can definitively identify the cognitive decline of dementia.

The first step a doctor should take is to consider overall health and changes over time. Family members or caregivers sometimes must provide this information, as the person with PD may not recall or be aware of all changes.

If a person with PD starts to experience dementia symptoms 1 year or more after their diagnosis, a doctor may diagnose the condition as PD dementia.

At this point, a doctor may also recommend imaging studies, such as an MRI scan. This can help identify any brain changes causing the symptoms, such as tumors.

No cure exists for PD dementia. Instead, treatments focus on reducing the symptoms of dementia and maintaining quality of life.

A doctor may prescribe certain medications, including:

  • Cholinesterase inhibitors: These medications help reduce the effects of cognitive decline in people with dementia. Rivastigmine is one such drug.
  • Antidepressants: Doctors often prescribe selective serotonin reuptake inhibitors (SSRIs) to reduce depression symptoms associated with Parkinson’s dementia. SSRIs include Prozac, Celexa, Lexapro, or Zoloft.
  • Clonazepam: This medication can help to enhance sleep quality.
  • L-dopa: This medication may reduce the movement issues that PD can cause but might make confusion and dementia symptoms worse.

However, many of these drugs are not intended for the treatment of Alzheimer’s, but doctors may still prescribe them ‘off label’

Doctors may also prescribe antipsychotic drugs but must do so with caution, as they may reduce psychotic episodes but have the adverse effect of increasing symptoms of Parkinson’s.

A combination of these medications typically provides the safest and most effective results. Discuss both benefits and side effects when considering treatments.

Learn more about the different medications for dementia here.

The life expectancy of people with PD dementia differs from those without dementia symptoms.

A 2017 study suggests that PD without dementia only moderately increased mortality compared to the general population.

The mortality rate of people with PD dementia, however, significantly increased.

While dementia impacts the survival rate, many medications, treatments, and support systems are available to a person with Parkinson’s disease.

Parkinson’s disease is a progressive condition that primarily affects movement and coordination. However, Parkinson’s can also affect cognitive function and may cause dementia.

Parkinson’s disease dementia may affect a person’s mood, memory, cognition, and speech.

People with Parkinson’s disease most commonly develop dementia symptoms 10 years after their initial diagnosis. Treatment cannot cure these conditions but may help reduce symptoms and improve a person’s quality of life.