Parkinson’s Disease Dementia
What is Parkinson’s Disease Dementia?
Overview
Parkinson’s disease dementia (PDD) is a type of dementia that affects individuals who have Parkinson’s disease, a progressive neurological disorder that primarily affects movement and coordination. Parkinson’s disease dementia usually develops several years after the onset of Parkinson’s disease and is often characterized by a decline in cognitive function, including memory loss, confusion, difficulty with language, and changes in mood and behavior.
As the years progress, patients living with Parkinson’s disease may develop cognitive decline, trouble with decision making, personality changes, and short-term memory complaints.
It is important to note that PDD is not the same as Alzheimer’s disease (AD). Patients with Parkinson’s disease (PD) are not at risk of developing AD. The cognitive changes of PD, even when severe enough to cause dementia, are not the same as those of AD. Typically long-term memory is not as affected, and patients retain recognition of loved ones and a general sense of awareness.
Cognitive changes and dementia can affect the vast majority of patients with PD, with the risk accumulating as the years pass and with greater age. Unfortunately, the prognosis is that around 75 percent of patients living with PD for more than ten years will develop dementia.
Rather than considering this as an inevitability, our focus at the Pacific Brain Health Center and Pacific Movement Disorders Center is to challenge ourselves and our patients to change the course of PD and find novel ways of preventing dementia.
Who is Affected?
PDD can affect anyone with Parkinson’s disease, though it is more common in:
- Individuals over age 65
- Those who have lived with Parkinson’s for 10+ years
- Patients with advanced motor symptoms or frequent hallucinations
- People with certain genetic factors or a history of repeated head trauma
Men are slightly more likely than women to develop PDD, and having additional health conditions affecting the brain or circulation can increase risk.
Parkinson’s Disease Dementia Symptoms & Causes
Symptoms
Signs and symptoms of Parkinson’s disease dementia include:
- Mental inflexibility with difficulty shifting focus or adapting to schedule changes
- Short-term memory loss, impacting daily routines like medication management
- Executive function difficulty with trouble making decisions or following multi-step processes
- Slow thinking or response times
- Reduced attention span or easily losing track of thoughts
- Problems with visual perception and depth judgment
- Sleep disturbances, including vivid dreams or REM sleep behavior disorder
- Psychosis (disconnection from reality)
- Hallucinations (seeing or hearing things that aren’t there)
- Delusions, often involving suspicion or paranoia
- Agitation or irritability
- Anxiety
- Depression
Causes
The exact cause of PDD is not yet known. However, Parkinson’s disease dementia is caused by the same underlying neurodegenerative process that causes Parkinson’s disease, which involves the degeneration of dopamine-producing neurons in the brain. As these neurons die, they lead to a shortage of dopamine, a neurotransmitter that plays a crucial role in controlling movement and cognitive function. The depletion of dopamine can cause various motor symptoms of Parkinson’s disease, such as tremors, rigidity, and slowness of movement, as well as the cognitive symptoms of PDD. While the exact triggers are not fully understood, a combination of genetic predisposition, environmental exposures, and age-related brain changes are thought to play a role.
When to See a Doctor
Early detection allows for timely treatment, support, and planning, which can improve quality of life. Contact your neurologist promptly if you or a loved one with Parkinson’s disease experiences:
- Noticeable decline in memory or problem-solving
- Increased confusion, disorientation, or trouble following conversations
- Sudden changes in mood or personality
- New hallucinations or delusions
- Difficulty managing daily activities that were previously routine
Parkinson’s Disease Dementia Diagnosis
The diagnosis of Parkinson’s disease dementia (PDD) typically begins with a confirmed diagnosis of Parkinson’s disease (PD), which is characterized by hallmark motor symptoms such as resting tremor, bradykinesia (slowness and smallness of movement), muscle rigidity (stiffness), and postural instability (balance problems).
Our experienced movement disorders neurologists regularly monitor patients for cognitive changes which could signal the beginning of dementia, utilizing evidence-based screening tests. If concern arises, detailed neuropsychological evaluation with clear delineation of cognitive strengths and weakness can be obtained. On occasion, volumetric MRI scanning or PET scanning may play a role.
A key challenge in diagnosing PDD is distinguishing it from Dementia with Lewy Bodies (DLB), also known as Lewy Body Dementia. Both conditions involve a combination of dementia (cognitive decline) and parkinsonism (motor symptoms such as slowness, stiffness, tremor, and imbalance). However, in PD, Lewy bodies are concentrated in the substantia nigra—a deep brain region—whereas in DLB they are more widespread from the start.
The primary diagnostic difference lies in the sequence of symptom onset:
- PDD – Parkinson’s motor symptoms appear first, often years before cognitive decline.
- DLB – Cognitive impairment develops before or at the same time as motor symptoms.
Additionally, people with PDD often experience significant improvement in motor symptoms with levodopa treatment, at least in the earlier stages. For a detailed comparison, see our PDD vs. DLB reference table.
It may be noted that patients with PD (with or without dementia) may have episodes of confusion or disorientation in the context of delirium, which can be precipitated by toxins, medications, or infections. Delirium waxes and wanes, so sudden declines in orientation, language, and behavior should prompt evaluation such as laboratory work, urinalysis, and potentially chest X-ray and MRI. Families should be reassured that with appropriate treatment of the underlying cause, patients often return to their previous baseline.
Parkinson’s Disease Dementia Treatmentrn& Outcomes
Treatment Options
Currently, statistics on cognitive change and dementia in PD come from studying patients who were first diagnosed ten or twenty years ago, prior to widespread recommendations about physical activity and exercise.
While no treatments have been proven to prevent development of Parkinson’s and dementia, there is strong reason to believe that physical and cognitive activity could play a powerful role in slowing disease progression in the early stages of Parkinson’s disease and throughout the course of disease.
Treatment of PDD involves the use of rivastigmine, an oral or transdermal (patch) medication that boosts the brain’s acetylcholine (one of the key neurotransmitters or brain chemicals).
Rivastigmine (Exelon) is the only medication FDA approved for PDD but other medications sometimes used “off label” include donepezil (Aricept), also an acetylcholine boosting drug, and memantine (Namenda), an NMDA receptor antagonist.
Medications for dementia help somewhat, and other treatments may play a role for behavior issues in PDD.
Research, including clinical trials, is ongoing to find disease-modifying treatments for PDD.
Patient Outcomes
While there is currently no cure for PDD, treatment can significantly improve symptoms, maintain independence longer, and enhance quality of life. Many people benefit from a combination of medications, therapy, and lifestyle adjustments.
Progression varies greatly between individuals. Factors such as overall health, age at onset, and early engagement in cognitive and physical activities can influence the rate of decline. Support from a multidisciplinary care team—including neurologists, neuropsychologists, therapists, and counselors—can help patients and caregivers navigate the challenges of PDD with greater resilience.
Managing Parkinson’s Disease Dementia
There is currently no cure for the condition. However, there are medications and other treatments available that can help manage the symptoms of PDD, including cholinesterase inhibitors, which can improve cognitive function, and levodopa, a medication that can help manage the motor symptoms of Parkinson’s disease. Lifestyle changes, such as regular exercise, a healthy diet, and cognitive stimulation, may also be helpful in managing the symptoms of PDD.
Experience Compassionate, Expert Care
At Pacific Neuroscience Institute’s Pacific Brain Health Center and Pacific Movement Disorders Center, we provide comprehensive, compassionate care for patients with Parkinson’s disease dementia (PDD). Our multidisciplinary team of specialists work closely with patients and families to manage both motor and cognitive symptoms. We combine advanced diagnostics, evidence-based treatments, and personalized care plans to help maintain independence, improve quality of life, and support caregivers every step of the way.
Learn More About Parkinson’s Disease Dementia
PDD is a form of dementia that develops in people with Parkinson’s disease, usually several years after motor symptoms begin. It affects memory, thinking, judgment, and behavior, while also impacting daily functioning.
Dementia in Parkinson’s typically develops in the later stages, often 10 or more years after diagnosis. However, the timing varies—some may experience cognitive changes earlier, while others may never develop dementia.
PDD refers specifically to dementia that occurs in the context of long-standing Parkinson’s disease. It is distinct from other dementias, such as Alzheimer’s or Lewy body dementia, and has unique symptom patterns and treatment approaches.
No, Parkinson’s disease itself is not a form of dementia. However, Parkinson’s can lead to dementia in its later stages, known as Parkinson’s disease dementia.
The “1-year rule” helps distinguish PDD from Lewy body dementia (LBD). If dementia develops at least one year after the onset of Parkinson’s motor symptoms, it is considered PDD. If cognitive symptoms appear before or within a year of motor symptoms, it is diagnosed as LBD.
Sundowning refers to increased confusion, agitation, or restlessness in the late afternoon or evening. While more common in Alzheimer’s, people with PDD may also experience sundowning due to changes in brain chemistry, fatigue, or environmental cues.
Resources
Get Expert Care from Leading Specialists
For those with Parkinson’s disease dementia, our movement disorders neurologists and brain health experts provide advanced diagnosis, and ongoing support. WIth individualized treatment plans we help patients and their caregivers manage symptoms and preserve quality of life.
Written and reviewed by:
The Pacific Neuroscience medical and editorial team
We are a highly specialized team of medical professionals with extensive neurological and cranial disorder knowledge, expertise and writing experience.
Last Updated: