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Some people diagnosed with Parkinson's will also experience mild cognitive impairment (MCI) symptoms. Generally, this appears in mid to late stages of Parkinson's Disease for 50% of those diagnosed with PD. Symptoms include memory problems and challenges with problem solving. It also impacts your ability to think and process information. Many people with mild cognitive impairment can think and analyze, communicate, remember information, and function normally. It is very common for a person with PD to have difficulty retrieving information, but uncommon that they forget who they or their family members are.

Because changes in cognition can be related to other potential conditions, it is important to update your physicians. Other medical conditions such as B12 deficiencies, thyroid disease, urinary tract infections, pneumonia, and even stroke may be a cause for confusion, hallucinations, and increased sleepiness. Ruling out triggers to cognition challenges is important for anyone experiencing these symptoms.

The primary areas of cognition that are impacted by Parkinson's Disease, include:

  • Executive Function (Problem Solving): Your brain has executive function that directs your body on how to make decisions, solve problems, initiate change, or meet a task head on. It also helps us with our activities of daily living. Problem solving and decision making can become difficult for people with Parkinson's experiencing cognitive issues.

  • Communication/Language: Some people with PD experience frustration when trying to speak, understand or follow conversations, especially when under pressure.

  • Speech: The most common cognitive issue in people with PD is a language problem often referred to as the "tip-of-the-tongue" phenomenon. A person with Parkinson's may know what they want to say but have difficulty finding the right words to say it, such as naming an object. Volume is also impacted in speech for people with Parkinson's.

  • Comprehension: Following explanations or too many details can overwhelm those living with Parkinson's. It can become difficult to shift thoughts from one to another.

  • Memory: Unlike Alzheimer's or other forms of dementia, memory issues in Parkinson's can come and go. What you remember one day, may feel fuzzing the next. This can impact things like knowing how to balance a checkbook or make coffee.

Your Movement Disorder Specialist or Neurologist may encourage you to see a neuropsychologist, which is a healthcare professional that specializes in understanding the relationships between your brain and your behavior. They can give you a cognitive evaluation and offer recommendations for maintaining and improving thinking skills or emotional functioning.

Medications are available to aid with some symptoms found in mild cognitive impairment. Other things like engaging in mental and physical exercise can also be a way to boost your brain's overall fitness. This could include completing crossword puzzles and interacting with games. Creativity can also enhance cognition in many people living with Parkinson's. 

Here are some tips to help with memory:

  • Keep a detailed diary of events and review it every day. Note important events or tasks that you need to complete.

  • Keep a calendar of appointments and engagements and review it daily.

  • Have paper and pencil by each phone in your home so that you can take messages easily.

  • Organize lists in categories to stimulate memory.

  • Focus on remembering main points, not trying to recall every detail.


For some people, cognitive change may never progress beyond the early stages. Others experience progression from cognitive changes due to aging.

In the later stages of PD progression, cognitive deficits can also worsen, sometimes resulting in dementia. The word "dementia" comes from Latin roots meaning "away" and "mind." It is not a specific disease, rather the term describes a group of symptoms associated with a decline in memory and thinking. It differs from mild cognitive impairment in that it affects thinking globally rather than just the one or two domains affected in MCI. People with dementia typically experience memory impairment and have trouble with executive function, visuospatial processing, and language.

Cognitive impairment becomes dementia when the loss of mental ability (or cognitive skills) interferes with activities of daily living and a person can no longer function in his or her daily life without relying on others. Parkinson's disease dementia (PDD) is generally an indication of disease progression. Although up to 30% of people with PD have cognitive changes early in the disease, not everyone with PD will develop dementia. The risk for dementia is relatively low among people under age 65, but by age 85, many people with Parkinson's experience some degree of dementia.

Dr. Friedman states, "In PD, memory problems are sometimes seen as worse than they are because some PD patients become slow thinking (bradyphrenia) or impaired by their medications. In the case of bradyphrenia, the patients are frequently not given sufficient time to answer questions or solve problems, and are assumed to not understand, when they simply haven't been given enough time to answer."

The likelihood of developing dementia has been associated with certain conditions. We refer to them as risk factors, but they have not been proven to cause dementia; rather, they appear to be present in people with PDD. These include:

  • Increasing age

  • PD onset at older age

  • Longer disease duration

  • Family history of dementia

  • Motor symptom severity

  • Changes in memory, concentration, and judgement

  • Trouble interpreting visual information

  • Muffled speech

  • Visual hallucinations

  • Delusions, especially paranoid ideas

  • Depression and lack of motivation

  • Irritability/moodiness and anxiety

  • Disorientation

  • Sleep disturbances or excessive daytime fatigue

Additionally, among Medicare beneficiaries with PD, dementia is most common in Black/African Americans and Hispanics.

If symptoms of dementia come on suddenly, you should report it immediately to a healthcare provider, as there is likely another cause. For example, delirium causes similar symptoms, such as disorganized thinking, unusual behavior, and hallucinations. However, delirium is reversible, because there is usually an underlying medical condition such as a urinary tract infection, or it can be a medication side effect. Delirium generally resolves quickly and may never appear again, while the symptoms of dementia are persistent, onset is gradual and permanent.

Dementia with Lewy Bodies

Dementia with Lewy Bodies (LBD) is a progressive, neurodegenerative disease in which abnormal deposits of a protein called alpha-synuclein build up in multiple areas of the brain. This is the same protein build up that is found in individuals with Parkinson's, but memory and thinking problems occur later in the disease for those with Parkinson's Disease Dementia.

If dementia occurs before or within one year of motor symptoms, a diagnosis of Lewy Body Dementia may be considered, especially if the person also experiences hallucinations. The lack of a strong symptom response to levodopa is another distinguishing factor. Dementia with Lewy Bodies is often referred to as an atypical parkinsonism, or a "Parkinson's plus" disorder (motor symptoms or Parkinson's, plus others). It is present in 5-15% of overall dementia cases. You may need to consult a movement disorder specialist to determine whether you have Lewy Body Dementia or one of the other atypical parkinsonism's. 

Symptoms of Lewy Body Dementia, include:

  • Problems with thinking (e.g., lack of judgement, loss of insight, decline in problem solving abilities)

  • Motor problems like those in PD: difficulty walking, tremor, slowness of movement, stiffness

  • Periods of being alert and coherent alternate with periods of being confused and unresponsive to questions

  • Visual hallucinations (usually occurring early on) and delusions

  • Unsteadiness, fainting, and falls

  • Visuospatial and depth perception problems

  • Depression

  • Sleep difficulties (may experience REM sleep disorder, which results in acting out dreams while asleep)

PDD is diagnosed when a person with PD has had motor symptoms for a year or more before they develop dementia symptoms. Lewy Body Dementia is diagnosed when a person develops dementia symptoms within a year or even before they develop the motor symptoms of PD.

Visuospatial Processing and Perception

You may have problems processing information about your surroundings or environment, even early in the disease. Some people with PD also experience changes in the amount of contrast sensitivity in the eye, making it hard to discern objects that are similar in color (e.g., white bread on a white plate). Later in the disease, people have more trouble navigating, sometimes even becoming lost, in familiar places. Visuospatial problems may contribute to the visual misperceptions or illusions that can occur in PD. You may be especially susceptible to this phenomenon in low-light situations. Other visual problems associated with aging, such as macular degeneration or cataracts, can also contribute to visuospatial problems. Like PD, these conditions may progress as time goes on.

Brain Power Boosters:
  • Exercise daily to boost cognitive health

  • Read and discuss articles in the newspaper or magazine

  • Read for pleasure. Use a red pen or highlighter to underline or circle important information as you read

  • Do cross word puzzles or word search puzzles

  • Go through old photos and make memory books for your children and grandchildren

  • Play board or card games

  • Consider getting involved in a social or service organization by volunteering

  • Learn a new skill, take a class, learn a new language or musical instrument

  • Create regular opportunities to be social with others

  • Continue working

  • Plan a household job to do every day


Davis Phinney Foundation for Parkinson's. Every Victory Counts, Your Go-To-Resource of Essential Information and Inspiration for Living Well with Parkinson's. Pages 67-69. "Manual." Sixth Edition, 2021


Parkinson's Foundation. Cognition. A Mind Guide to Parkinson's Disease. "Brochure."


Marie, Liane.​ Parkinson's Dementia. Chapter 56, pages 175-176; Dementia with Lewy Bodies, Chapter 57: Pages 177-178; The Complete Guide for People with Parkinson's Disease and Their Loved Ones. Purdue University Press. 2022.

Friedman, MD. Joseph H. "Making the Connection Between Brain and Behavior: Coping with Parkinson's Disease." Chapter 7. Dementia. Pages 75-88.  Second Edition. DemosHealth 2013

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