Thinking Changes & Dementia

A broad spectrum of potential thinking and memory changes can occur in people with Parkinson’s disease (PD), including slowed thought processes, forgetfulness, confusion when doing routine tasks, lack of judgment, compulsive behaviors, paranoia, anxiety, hallucinations, delusions and personality changes.

When thinking changes are mild (known as mild cognitive impairment), symptoms often do not interfere with daily activities. As PD advances, people can develop more profound changes in thinking.

Sudden changes in cognition are not typical of PD and should be evaluated for another cause, such as a urinary tract infection (or other infections) or medication side effects. Promptly report any new or sudden changes in thinking or behavior to the healthcare team. Some changes to cognition can be reversible if the underlying cause is addressed.

Cognitive Changes

Cognitive Changes

Thinking changes, also known and cognitive change, are common in Parkinson’s. There are different types, from mild to advanced types of cognitive change. Learn more about these changes, their signs and symptoms.

Thinking Changes

At this time, there is no reliable tool to predict who will or won’t develop thinking changes (also known and cognitive changes) in PD. Not everyone with mild cognitive changes will develop dementia.

If your loved one is experiencing thinking changes, keep the below in mind:

  • As with motor symptoms, your loved one can have good days and bad days
  • When evaluating your loved one for cognitive change, their PD doctor may interview them and their primary caregiver
  • Your loved ones PD doctor may ask you to help apply specific strategies that can help address cognitive changes
  • Consider making adjustments to your home to help minimize memory, vision and perception or orientation difficulties. Strategies include decluttering and simplifying living areas to reduce confusion and using low-level nighttime lighting to reduce visual misperceptions and confusion.
  • Helping your loved one follow a structured, regular day-to-day routine can also help people with Parkinson’s-related dementia feel more comfortable


Dementia is when someone experiences problems in memory and thinking that are advanced and interfere with daily activities and quality of life. While not everyone with PD will develop dementia, some do.

Dementia can have a great impact on the ability to participate in social settings and perform basic activities due to the decrease of cognitive ability and motor skills. Dementia can also have severe effects on the caregiver. In fact, significant cognitive decline in the person with PD is very commonly associated with caregiver stress, strain and burnout.

As dementia progresses, fact and fantasy can become confused, which can lead to acting out. People with moderate to severe dementia may become disoriented and unable to be left alone. They may show signs of agitation, mood fluctuations, increases in impulsive decision-making and paranoia.

Hallucinations (seeing something that’s not there) and delusions (beliefs conflicting with reality) can come with thinking changes, but they can also be caused by PD medications themselves.


Hallucinations, Illusions and Delusions

Your loved one’s doctor may talk to you about psychosis. The word psychosis refers to a break with reality — and may range from confusion (disordered thinking) to seeing things that aren’t there (hallucinations), to believing things that are not true (delusions).

Between 20-40% of people with Parkinson’s report the experience of psychosis. These statistics sometimes include temporary symptoms due to medication side effects or hallucinations.

Treatments for Hallucinations and Delusions

Once a doctor confirms that the hallucinations are not due to a specific cause, make sure that any medication prescribed for hallucinations is an “atypical antipsychotic” (does not block dopamine).

The atypical antipsychotic medication used in PD are clozapine (Clozaril, FazaClo, Versacloz), pimavanserin (Nuplazid) and Quetiapine (Seroquel, Seroquel XR). Review our list of contraindicated medications in PD, available in our downloadable Hospital Safety Guide.


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Care Partner Tips for Helping A Loved One With Cognitive Impairment


Communicating with someone who is a slower thinker can be frustrating. Sometimes small adjustments can make a big difference in making sure your loved one has the opportunity to communicate with you and others. Try some of these strategies and share them with others who interact with your loved one on a regular basis:

  • Ask one question at a time. People with Parkinson’s sometimes have trouble taking in complicated information, so slowing down and breaking apart requests that require multiple answers can be helpful.
  • Pause for a response. Give your loved one time to respond to a question before assuming that he or she does not care to answer or didn’t hear you. Try counting to 10 before asking the question again.
  • Adjust your question style. Ask either/or questions instead of open-ended questions. For example, instead of asking, “What do you want to wear today?” ask, “Do you want to wear the red shirt or the blue shirt?”
  • Give hints and cues. Try giving a one- or two-word hint if the person with Parkinson’s has difficulty finding a word or loses his or her train of thought. Use short, simple phrases to provide cues and avoid using too many words when providing direction.

Calming Your Loved One

Implementing prevention strategies can help you avoid situations that cause your loved one distress. In addition to helping the person with PD, creating strategies to help manage your loved one’s dementia can help your stress and emotional pain. Try these tips to calm the person with PD:

  • Serve meals and arrange visits at the same time every day. Many people with Parkinson’s benefit from a regular routine in their day-to-day activities and feel more comfortable with a clear, structured schedule.
  • Simplify the décor of the living area. Reducing excessive stimuli may help with distractibility or confusion and can help minimize memory, visual-perceptual or orientation difficulties.
  • Use a nightlight or low-level lighting to help reduce visual misperceptions and confusion at nighttime.
  • Keep calm and still while you talk to your loved one; avoid speaking sharply or raising your voice. People with dementia may respond with impatience or even aggression if they can’t find the right words to express what they mean. Try asking if they can explain in a different way. Listen for clues and pay attention to body language.
  • Demonstrate your care and affection for your loved one. Maintaining physical contact throughout the stages of dementia is important.

General Tips

  • Multitasking is not your friend. Limit distractions as you try to accomplish the daily routine or have meaningful conversation.
  • Try using humor to diffuse a stressful situation. A well-placed laugh can make everyone feel better. However, avoid using negative humor or sarcastic remarks, which can be hurtful. You want to laugh with your loved one, not at them.
  • Resist the urge to argue or correct. If your loved one says something you know isn’t true, try to find ways around the situation, instead of contradicting them. Consider repeating this to yourself when your loved one is experiencing delusions: “It is the disease making these accusations, not my loved one.”
  • Watch out for sensitivity to medications. Many antipsychotic medications that are commonly prescribed for people with Alzheimer’s are contraindicated (when a drug can be harmful) in PD and can cause severe, sometimes dangerous, side effects. Be vocal about avoiding these medications, especially in a hospital setting where health care professionals may not be familiar with PD. Review our list of contraindicated medications in PD, available in our downloadable Hospital Safety Guide.
  • Look for community resources BEFORE you need them. No two cases of PD or dementia are alike, and the speed of progression varies. Explore resources in your community, such as the Area Agency on Aging; services like home health aides and visiting nurses; and residential support like respite care and long-term care facilities before you need them.
  • Don’t forget to care for yourself. Significant cognitive decline not only impacts the person with Parkinson’s but also is associated with care partner stress. To best care for your loved one, remember to prioritize self-care. Learn more in our Caring for the Care Partner article.
  • Be present. If the person with PD is not responsive, it can be tempting to speak about loved one as if he or she weren’t there. Remember that the person with PD is the same person and has the same feelings and needs as before.
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