Over time, some people with Parkinson’s disease experience declines in cognitive function. When these changes interfere with daily life, it may be a sign of Parkinson’s disease dementia (PDD).
Recognising how PDD develops is essential for timely support.
In this guide, you’ll learn:
- Parkinson’s disease dementia and how it differs from other dementia types
- Diagnosis and early signs
- Treatment options
We’ll also cover how daily habits can support the ongoing management of PDD.
What Is Parkinson’s Disease Dementia?
Parkinson’s disease is a movement disorder associated with body tremors, shakiness, and movement difficulties. It is not a form of dementia itself. However, some people with Parkinson’s disease later develop cognitive changes that lead to dementia.
This later condition is called Parkinson’s disease dementia (PDD).
According to the Alzheimer’s Association:
- An estimated 75% of people who live with Parkinson’s for more than 10 years will go on to develop PDD
- On average, it takes about 10 years for dementia symptoms to develop after the onset of Parkinson’s disease
Lewy Bodies & Parkinson's Disease
Parkinson’s disease begins when nerve cells that produce dopamine in the brain start to break down. Over time, the changes can spread to brain areas involved in thinking, memory, and behaviour.
To make things more complicated, PDD is linked with the presence of Lewy bodies: abnormal microscopic deposits largely made of alpha-synuclein, a protein found in the brain. These deposits are also found in a type of dementia called ‘Dementia with Lewy Bodies’ (DLB).
Some researchers suggest that PDD and DLB are different phases of the same condition, given their shared pathology and overlapping symptoms.
Timing of Parkinson’s Disease Dementia (PDD)
If somebody has dementia before or at the same time as developing Parkinson’s disease, it will likely be diagnosed as Lewy body dementia.
On the other hand, PDD typically appears more than a year after the onset of Parkinson’s disease symptoms.
The term 'mixed dementia' is used if the brain shows signs that more than one type of dementia is present.
👉 To understand more about the types of dementia, see our article: What Is Lewy Body Dementia?
Recognising The Symptoms
No two people experience PDD in the same way. That said, some common changes often appear gradually:
- Difficulty focusing or problem-solving
- Slower thinking (also called bradyphrenia)
- Memory lapses or trouble finding the right words
- Changes in mood such as apathy, depression, or irritability
- Poor judgment or trouble planning
- Hallucinations or delusions
- Sleep disturbances
If a loved one has PDD, you might notice small shifts in conversation or confusion in familiar settings. Over time, these symptoms may affect their ability to manage money, follow recipes, or even recognise loved ones.
It can be easy to dismiss early cognitive symptoms as aging. But when these patterns start to impact daily life, it’s time to speak with a doctor.
✅ Tip: Keep a record of noticeable changes to share with healthcare professionals. It helps with clearer diagnosis and tracking over time.
👉 Recognise the signals with our quick guide: The Early Signs of Dementia Checklist
How Is It Diagnosed?
There’s no single test to confirm PDD. Instead, diagnosis is based on a combination of:
- Neurological and cognitive tests
- Medical history and symptom timeline
- Brain imaging (such as MRI) to rule out other causes
- Functional assessments to measure how symptoms affect daily life
If you’re supporting a loved one through this process, consider accompanying them to appointments and sharing specific examples. Doctors will look for patterns and want to know when memory issues arose after the onset of Parkinson's.
Don’t wait for a crisis. Early diagnosis opens the door to treatments and long-term planning.
Managing Life with Parkinson’s Disease Dementia
While there is currently no cure for PDD, a variety of strategies can alleviate symptoms and improve quality of life. It’s helpful to adopt a team-based approach involving family, clinicians, and supportive tools.
1. Medications
While medications do not reverse the progression of PDD, they can help improve symptoms. Always speak with a doctor before changing any medication.
👉 See this article by MedCentral for examples of PDD medications
2. Occupational and Speech Therapy
Parkinson’s disease affects facial expression along with movements of the mouth, chest, and throat, making communication more difficult.
When combined with the mental challenges of dementia, cognitive, speech, and swallowing therapies can greatly help day-to-day functioning of those living with PDD.
3. Lifestyle Support
Maintaining regular routines around food, movement, and sleep remains important for those with PDD maintain their physical wellbeing and cognitive function.
👉 For more guidance in this area, we recommend reading: Living Well With Cognitive Impairment
4. A Safe Environment
Designing a safe, dementia-friendly environment can help people with PDD live independently at the comfort of home, for longer.
Simplify living areas by reducing clutter. You can add labels around the home for memory support.
Concerned about a loved one’s safety while you're away? Consider setting up a medical alarm system or smart home devices.
5. Strong Routines
Building solid, predictable routines can help people with PDD feel less stressed and more comfortable.
At Elli Cares, we know that managing PDD involves tracking many moving parts. That's why caregivers across the world use the Elli app to regularly:
- Check on loved ones from afar
- Coordinate care with other family or carers
- Set GPS “safe zones” to reduce the risk of wandering
- Build routines with personalised text, voice, or video reminders (like “time to eat”)
App reminders can also alert you when a loved one has completed an important task, such as taking their medications.
📲 Learn how to craft reminders that stick with our guide: Elevating Reminders Beyond Medication
Moving Forward With Confidence
Parkinson’s disease dementia can shift the rhythm of everyday life for the person diagnosed, and everyone involved in their care. Tasks that once felt simple may now need more thought and patience.
These changes can be disorienting at first.
But with greater awareness and the right tools in place, we can empower people with PDD to live with greater dignity, connection, and comfort.
✅ Curious? Learn how assistive tools can support aged care:
🔎 Top Tech Tools That Help Seniors Safely Live Alone
