Parkinson’s Disease Dementia

What is Parkinson’s disease dementia?

Parkinson’s disease dementia is a decline in thinking and reasoning skills that can develop after a Parkinson’s disease diagnosis. It develops at least one year — but usually longer — after the initial Parkinson’s disease diagnosis.

Dementia is a decrease in mental function from a previously higher level that’s severe enough to interfere with daily living. Having dementia means you have a decline in two or more of the following:

• Memory.
• Reasoning.
• Language.
• Coordination.
• Behavior.

People typically experience mild cognitive impairment (MCI) in the course of Parkinson’s disease before developing dementia. But MCI doesn’t always progress to dementia. About 10% to 20% of people with Parkinson’s disease present with MCI during the entire course of the Parkinson’s disease.

Parkinson’s disease is a neurodegenerative brain condition that mainly affects your movements, causing tremors, slowed movements (bradykinesia) and other issues. But it can also affect the parts of your brain responsible for mental functions. This is when dementia may develop.

How common is Parkinson’s dementia?

The frequency of Parkinson’s dementia varies based on age and how long you’ve had Parkinson’s disease. For example, Parkinson’s dementia affects:

• 16% to 20% of people between 60 and 75 years who’ve had Parkinson’s for between five and 10 years.
• 20% to 30% of people between 60 and 75 years who’ve had Parkinson’s for between 10 and 15 years.
• 50% to 60% of people over 75 who’ve had Parkinson’s for more than 15 years.

What are the symptoms of Parkinson’s disease dementia?

Parkinson’s dementia can affect people in many ways. Common symptoms include:

• Impaired attention, like difficulty focusing.
• A decline in memory.
• Issues interpreting visual information, like difficulty spotting objects in a cluttered space.
• Difficulty planning, starting or completing simple tasks.
• Language challenges, like misnaming objects or difficulty understanding complex sentences.
• Muffled speech.

Parkinson’s dementia behavior symptoms are also common and include:

• Mood changes, like depression, irritability and anxiety.
• Apathy (a lack of goal-directed behavior).
• Psychosis, including hallucinations (especially visual) and delusions (especially paranoid thinking).

If you notice these symptoms in yourself or a loved one, see a healthcare provider.

What causes Parkinson’s dementia?

A buildup of Lewy bodies (proteins called alpha-synuclein) causes Parkinson’s disease. This buildup damages nerve cells (neurons) in your brain.

The buildups typically first affect the basal ganglia of your brain in Parkinson’s disease, which controls movement functions. Over time, the Lewy bodies can spread to parts of your brain that control cognitive functions, leading to Parkinson’s dementia.

Parkinson’s dementia is closely related to another condition called Lewy body dementia (LBD). Studies show that LBD and Parkinson’s disease may be linked to the same underlying abnormalities in the brain processing of alpha-synuclein. LBD and Parkinson’s disease dementia are nearly indistinguishable except for the order in which the symptoms develop.

What are the risk factors for Parkinson’s disease dementia?

The most significant risk factors for Parkinson’s disease dementia are increasing age and increasing years of having Parkinson’s disease. In other words, the older you are and the longer you’ve had Parkinson’s disease, the more likely you’ll develop Parkinson’s dementia.

Studies show that having the following features of Parkinson’s disease also increases your risk of developing Parkinson’s dementia:

• Severe movement (motor) symptoms.
• Issues with autonomic nervous system functioning (like orthostatic hypotension and loss of bladder control) early in the course of Parkinson’s disease.
• Symmetrical (affecting both sides of your body) movement symptoms.
• Dopamine-related medications for Parkinson’s disease being less effective than expected.
• Having REM sleep behavior disorder.

How is Parkinson’s dementia diagnosed?

There are no tests that conclusively diagnose Parkinson’s disease dementia. Instead, your healthcare provider will:

• Ask about when your symptoms developed and how they’ve changed.
• Ask about your medical history.
• Review your current medications.
• Ask about your family’s medical history.

They may also order tests, including laboratory tests, imaging tests and neuropsychological tests (thinking tests) to support the diagnosis.

Because Parkinson’s dementia and Lewy body dementia have very similar symptoms and causes, providers use the following guidelines to diagnose each condition:

• The diagnosis is Parkinson’s disease dementia if you experience dementia at least one year (usually several years) after the onset of Parkinson’s movement symptoms.
• The diagnosis is Lewy body dementia if you experience dementia either before, at the same time or within one year of the onset of Parkinson’s disease symptoms. In some cases of LBD, symptoms of Parkinson’s, like changes in movement, may not occur.

What is the treatment for Parkinson’s dementia?

There are currently no treatments that can slow or stop the progression of Parkinson’s dementia. But medications and therapies may improve some of the symptoms of dementia, like:

• Cholinesterase inhibitors: This class of medications, which includes donepezil (Aricept®), rivastigmine (Exelon®) and galantamine (Razadyne®), may help symptoms like visual hallucinations and changes in thinking and behavior.
• Selective serotonin reuptake inhibitors (SSRIs)and serotonin and norepinephrine reuptake inhibitors (SNRIs): These antidepressant medications may help with mood and/or anxiety symptoms.
• Cognitive behavioral therapy: This type of talk therapy (psychotherapy) may help manage behavioral symptoms of dementia.

Your healthcare team will work with you to figure out which treatment options are best. Some medications can make dementia symptoms worse. For example, carbidopa-levodopa — the go-to medication for movement symptoms of Parkinson’s disease — can sometimes worsen hallucinations and confusion in those with Parkinson's disease dementia.

There may also be clinical trials on new treatments for Parkinson’s disease dementia. Ask your provider if this is an option for you.

Can I prevent Parkinson’s disease dementia?

Unfortunately, there’s nothing you can do to prevent Parkinson’s dementia from developing. You also can’t reduce your risk of developing it.

What is the prognosis for someone with Parkinson’s disease dementia?

The prognosis (outlook) for someone with Parkinson’s disease dementia varies based on certain factors. But the nature of both Parkinson’s disease and Parkinson’s disease dementia is that they worsen over time.

While treatment can help improve symptoms, the quality of life is often poor.

How fast can Parkinson’s disease dementia progress?

The speed of progression (worsening) of Parkinson’s disease dementia can vary widely from person to person, much like the progression of Parkinson’s disease. Your healthcare team will be able to give you and your family a better idea of what to expect given your unique circumstances.

How can I help a loved one with Parkinson’s disease dementia?

Aside from working with your loved one’s healthcare team to get them the best care, other steps you can take include:

• Learning as much as you can: Being proactive and finding out as much as possible about Parkinson’s dementia can help you feel more prepared for what’s to come and be a more informed advocate for your loved one.
• Simplifying their living space: Decluttering and simplifying living areas can help reduce confusion. Using low-level nighttime lighting can help reduce visual misperceptions.
• Having a structured routine: A structured day-to-day routine can help people with Parkinson’s disease dementia feel more comfortable.
• Joining a support group: Encourage your loved one to join a Parkinson’s disease support group — and attend one yourself. These groups can provide valuable information, advice and experience to help people with Parkinson’s disease and their loved ones cope with a wide range of issues.

Is Parkinson’s disease dementia different from regular dementia?

There are several causes of dementia and it has wide-ranging symptoms. Alzheimer’s disease is the most common cause of dementia. Researchers note that there may be some differences in the features of Parkinson’s disease dementia compared to Alzheimer’s disease dementia. For example:

• People with Parkinson’s disease dementia tend to have more severe apathy and more prominent attention impairment compared to people with Alzheimer’s disease dementia.
• People with Alzheimer’s disease dementia tend to have language difficulties earlier than people with Parkinson’s dementia. They’re also more likely to have difficulty forming new memories compared to people with Parkinson’s dementia.

Are there Parkinson’s dementia stages?

While healthcare providers have a standardized rating scale to classify Parkinson’s disease itself, they don’t have a tool for understanding the stages of Parkinson’s disease dementia. Parkinson’s dementia affects each person differently and progresses at different rates. So, it’s difficult for researchers and providers to classify it into stages.