Parkinson’s disease (PD) is known most for its associated movement (or motor) symptoms, such as tremor and slowed movement, but cognitive changes can also be among the common PD non-movement symptoms.
About half of those with Parkinson’s will be affected by mild cognitive impairment — changes in memory and thinking that are noticeable, but not enough to affect daily activities.
As the disease progresses, people living with PD can develop more significant or severe memory and thinking problems, sometimes called dementia. The term dementia means that a person has permanent cognitive changes that are significant enough to impact daily living. The combination of movement and cognitive impairments can be particularly challenging, even limiting a person with Parkinson’s ability to participate in social settings and perform basic activities.
Dementia or significant cognitive decline can also seriously impact care partners and is associated with care partner stress. To best care for those living with the disease, care partners of people with Parkinson’s-related dementia must also prioritize self-care.
Issues and Parkinson’s symptoms associated with mood, sleep, medications or other medical problems can all look like dementia. Because many other factors can impact cognitive skills in PD, an accurate diagnosis is essential.
Types of Dementia
Changes in the structure and chemistry of the brain can cause memory and thinking problems in Parkinson’s. Alpha-synuclein, a protein that is central to Parkinson’s, forms sticky clumps, called Lewy bodies, that can disrupt normal brain functioning and lead to dementia. Because of this, the term ‘Lewy body dementia (LBD)’ may sometimes be used.
Lewy body dementia includes two different types of related dementias, distinguished by which symptoms start when:
- Parkinson’s disease dementia (PDD) – diagnosed when a person living with PD experiences significant cognitive decline after a year or more of motor symptoms (most typically after many years of experiencing motor symptoms).
- Dementia with Lewy Bodies (DLB) – diagnosed when cognitive decline is the earliest symptom, or when cognitive decline and motor symptoms begin and progress together.
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Symptoms of Dementia
Potential thinking, memory and behavior changes among people with Parkinson’s disease dementia can be wide-ranging.
Memory Changes and Confusion
Signs can range from forgetting how to do simple tasks, such as making coffee, to difficulty concentrating, learning, remembering or problem-solving:
- People with PDD can become disoriented and confused.
- People with PDD can experience short- and long-term memory impairment.
Mood Changes, Hallucinations and Paranoia
People with PDD can become agitated, irritable or even aggressive. Other Parkinson’s disease dementia experiences can include:
- Hallucinations – seeing, hearing or feeling things that are not real.
- Delusions – strange or unrealistic beliefs including paranoid thinking, suspicion or distrust.
Visual Perception Difficulties
PDD can cause subtle visual-perceptual problems. These problems can contribute to visual misperceptions or illusions. This can include difficulty finding objects in a busy space or trouble navigating familiar or unfamiliar places. Nighttime low light or macular degeneration can increase these challenges.
People with Parkinson's disease dementia can experience communication difficulties:
- As PDD advances, people may experience problems naming objects or may misname them.
- Difficulty comprehending complex sentences, such as a question or information without giving more detail.
- Speech problems, such as trouble producing words even when they can think of the word they want to say. Movement symptoms can cause slowed or slurred speech.
The Differences Between Parkinson’s Dementia and Alzheimer’s Disease
The advanced cognitive changes that impact daily living in Alzheimer’s and Parkinson’s are both types of dementia.
Parkinson’s disease dementia (PDD) can occur as Parkinson’s advances, after several years of motor symptoms. Dementia with Lewy Bodies (DLB) is diagnosed when cognitive decline happens first, or when Parkinson’s motor symptoms and cognitive decline occur and progress closely together.
Alzheimer’s, a fatal brain disease, causes declines in memory, thinking and reasoning skills. Physicians (often with the help of specialists such as neurologists, neuropsychologists, geriatricians, and geriatric psychiatrists) can diagnose Alzheimer’s. Visit the Alzheimer’s Association to learn the 10 signs of Alzheimer’s disease.
Parkinson’s disease dementia tends to be less disabling than Alzheimer’s disease. People with Alzheimer’s disease have language difficulties earlier than people with Parkinson’s, and they are unable to form new memories unlike in PD.
PD Dementia and Safety Concerns
Safety issues should be considered and monitored from the time of diagnosis. As PDD progresses, ensure that your loved one is not left alone and try to:
- Evaluate driving privileges before safety is a concern. Your doctor can make a driving evaluation referral.
- Work out legal and financial issues and safeguard finances. People with dementia are at greater risk of falling victim to scams and fraud.
- Minimize prescription risks. Confirm with the doctor the medication names and doses of the person with PD. If the person is in dementia’s early stages and capable, fill up their weekly pill box together and monitor use.
- Look into medical alert systems. These systems can be critical in the event of a fall or if your loved one wanders outside of the home. Many types of systems are available, from bracelets and pendants to smartwatches with fall detection and one-button connections to 911.
- Evaluate gun safety. If your loved one owns a firearm or has one in the home, consider bringing it up with their doctor and taking additional safety precautions.
Tips for Communicating with a Person with PDD
PD-related mood and motor changes can impact communication; cognitive changes and Parkinson’s disease dementia can further these difficulties.
- Stay calm and be patient. It is not usually helpful to try to reason or argue with someone experiencing a hallucination or delusion. If the person is frightened by the hallucination or delusion, try to redirect their attention to something else.
- Acknowledging what the person is seeing, even if you do not see it, can reduce stress.
- Speak slowly and at eye level. Communicate in simple sentences.
- Ask one question at a time and wait for an answer.
- Limit distractions. Turn off the TV or radio before asking a person with PDD to do something.
- Consider causes behind disruptive behavior. Can your loved one be hungry, thirsty, tired, in pain, frustrated, lonely or bored?
- If the person is stuck on an idea, try agreeing with them, then changing the subject.
- It’s okay to use humor to diffuse stressful situations but avoid negative humor or sarcasm ― these can be misunderstood.
Page reviewed by Dr. Chauncey Spears, Clinical Assistant Professor and Dr. Sydney M. Spagna, Clinical Fellow at the University of Michigan.