The Stages of Parkinson’s Dementia

by Claire Gillespie Health Writer

When it comes to Parkinson’s disease (PD), there are five distinct stages during which symptoms—like tremors and limb rigidity—get progressively worse. But the stages of Parkinson’s disease dementia (PDD) aren’t as clear cut. “As Parkinson’s disease progresses, many patients also develop cognitive decline, to the point of having difficulty taking care of themselves independently. This is known as Parkinson’s disease dementia,” says Melita Petrossian, M.D., a neurologist and director of the Movement Disorders Center at Providence Saint John’s Health Center in Santa Monica, California. But not everyone experiences PDD in the same way.

senior confused

Early Signs of Parkinson’s Disease Dementia

In the beginning, PDD can be subtle. “Early on, there may be memory loss and difficulties with daily activities,” says Michael S. Okun, M.D., executive director of the Norman Fixel Institute for Neurological Diseases at University of Florida Health in Gainesville. Delusions or hallucinations may also start to happen. Dr. Petrossian points out that there can be an overlap between the early signs of dementia and mild cognitive impairment due to Parkinson’s disease, which can make it difficult to learn new skills and recall information or conversations.

talking to doctor

Identifying PDD

There is no single test for PDD. “The best way to identify Parkinson’s disease dementia is to carry out a complete neuropsychological examination,” says Dr. Okun. This is an in-depth process carried out by a trained neuropsychologist, involving multiple mental tasks and tests spread over several hours. Other ways to assess cognitive decline or dementia in people with Parkinson’s disease include the Montreal Cognitive Assessment (MoCA) or Folstein Mini-Mental Status Exam (MMSE), both short (10 minutes or so) pen-and-paper tests that look at executive function, language, visual and verbal memory, spatial skills, processing speed, and mood symptoms.


Typical Timescale for PDD

According to the Parkinson’s Foundation, PDD is typically diagnosed when a person living with Parkinson’s disease experiences cognitive decline after a year or more of motor symptoms. But in most cases, people experience many years of tremors, slowness of movement, and muscle cramps before showing signs of significant cognitive decline. The Weill Institute for Neurosciences estimates the average time from onset of movement problems to developing dementia is 10 years. An estimated 50% to 80% of people with Parkinson’s will eventually experience Parkinson’s disease dementia, says the Alzheimer’s Association.

Man receiving a prescription from a pharmacist

Treating Parkinson’s Disease Dementia

A treatment plan for PDD typically includes medications that boost the brain’s level of certain neurotransmitters and help improve memory and processing speed, Dr. Petrossian says. Exercise is also an important part of the treatment plan—Dr. Petrossian recommends skill-based activities like boxing or dance to boost cognitive function as well as fitness. “PDD symptoms should be monitored long-term by a neurologist, and in some cases a psychiatrist,” says Dr. Okun. In many cases, physical, occupational, speech, and social work therapy can also be useful since PPD affects all aspects of life.

senior painter

Living With PDD

PDD is a progressive disease, so the symptoms become more severe over the years. In the early stages, the Parkinson’s Foundation recommends including the person with dementia in all decisions about their treatment and care. Cognitive and social stimulation is crucial for people with PDD, agrees Dr. Petrossian. Family members will want to arrange scheduled activities, like lunches with friends, art classes, music classes, and language lessons, on top of physical activity and speech exercises.


When PDD Progresses

In the advancing stages of Parkinson’s disease dementia, legal and logistical issues may arise. For instance, family members may need to safeguard their loved ones from falls due to forgetting to use a walker and monitor their medication management. It’s important for people with PDD to have their powers of attorney (both legal and medical) in place while they have the cognitive ability to do so.

Caregivers should also check their state’s regulations regarding dementia and driving. For instance, in California, doctors are required to notify the Department of Motor Vehicles (DMV) if a person has been diagnosed with dementia, and the patient then needs to take another driving test.

walking seniors

Your Future With PDD

Parkinson’s disease itself isn’t fatal (although complications from the condition can be, such as severe falls and pneumonia). On average, people with Parkinson’s disease can expect to live almost as long as those without it. On the other hand, “because dementia tends to occur in later stages of Parkinson’s, life expectancy is logically shorter in patients with dementia compared to those without it,” says Dr. Petrossian. Generally, life expectancy of PDD is one to two years shorter than Parkinson’s without dementia.

Lewy bodies

PDD vs. Dementia With Lewy Bodies

Another type of dementia is called Dementia with Lewy Bodies (DLB), which has similar symptoms to PDD. DLB is associated with abnormal deposits (aka Lewy bodies) of a protein called alpha-synuclein in the brain. Lewy bodies are also found in the brains of people diagnosed with PDD.

However, DLB is diagnosed when cognitive decline happens before the motor symptoms of Parkinson’s, or when motor symptoms and cognitive decline occur and progress closely together.


PDD vs. Alzheimer’s

The term dementia is often used synonymously with Alzheimer’s, but Dr. Petrossian points out that dementia is a general term, referring to progressive cognitive decline causing loss of functional independence. “PDD differs from other causes of dementia—such as Alzheimer’s—in that the difficulties tend to be related to loss of executive function, for instance the ability to visualize and complete multi-step tasks such as meal preparation,” she explains.

According to the Parkinson’s Foundation, PDD is less disabling than Alzheimer’s. However, somebody with Parkinson’s disease may have Alzheimer’s, and it’s possible to have both PDD and Alzheimer’s—another reason why anyone who experiences PDD experiences them in a unique way.

Claire Gillespie
Meet Our Writer
Claire Gillespie

Claire Gillespie writes about mental health, psoriasis, psoriatic arthritis and IBS for HealthCentral. She is a passionate about mental health awareness, and also writes about health and wellness for other sites, including Vice, SELF, Zocdoc, Reader’s Digest, and Healthline. You can follow her on Twitter @southpawclaire.