Cognitive Changes

Reviewed by: HU Medical Review Board

The ability to think or mentally process is known as cognition. Problems or changes in cognition are common in Parkinson's disease (PD). These changes vary in severity from person to person. But they can be a significant problem or disability for both the person with PD and their caregiver.1

Why does Parkinson’s cause cognitive changes?

The cause of cognitive changes in PD is not fully understood. But the damage to multiple areas of the brain caused by PD is probably responsible. The basal ganglia and frontal lobes are 2 areas of the brain that are commonly affected in PD. These areas play a role in thinking skills and executive functions, which are the skills needed to carry out a task. It is also possible that the drugs used to treat PD may add to cognitive changes.1

Cognitive changes in PD

Like other PD symptoms, changes in thinking and mental processing vary greatly from person to person. Areas most likely to be impacted include:1


Damage to the basal ganglia and frontal lobes can result in the person with PD having difficulty organizing and recalling information. It might also look like problems doing simple tasks, for example getting lost in familiar places or forgetting how to make coffee.1


Poor attention span is another common problem for people with PD. Many people with PD find it hard to stay focused on a task for a long period of time. They may also have trouble switching from one activity to another.1

Executive functions

Executive functions are the skills that help us plan, organize, and complete tasks. People with PD may have trouble with these skills (called executive dysfunction). Executive dysfunction is common in PD. It can make it hard for the person with PD to do tasks like following a recipe or balancing a checkbook.1

Thinking and processing

People with PD often have a slower thinking and processing speed. This can make it challenging to solve problems, understand complex instructions, or keep up with a conversation.1


Some people with PD have changes in their speech and language. This can include slurred speech, difficulty finding the right words, or changes in how they pronounce words. Changes in speech and language can make it hard to communicate with others.1

Visual-spatial abilities

Some people with PD have problems with their visual-spatial abilities. This means they have difficulty processing information that comes in through their eyes. They may have trouble judging distances, remembering the layout of a room, or recognizing objects. This can make it hard to drive or navigate around town.1

What is dementia?

Dementia refers to a severe loss of cognitive function that causes significant problems with daily activities, jobs, or social interactions. Dementia is a permanent change in thinking and mental processing that interferes with daily living.2

If dementia does occur, it often happens many years or decades after a person is diagnosed with Parkinson's disease.2

Parkinson's disease dementia versus dementia with Lewy bodies

Parkinson's disease dementia (PDD) is a form of Lewy body dementia. Lewy bodies form in the brain and clump together in nerve cells. These nerve cells with Lewy bodies lose their function.

There is another condition known as dementia with Lewy bodies (DLB). In both PDD and DLB, Lewy bodies form in the brain and cause nerves to malfunction.2,3

Parkinson's and dementia with Lewy bodies have very similar symptoms including cognitive dysfunction and parkinsonian movement (motor) symptoms.

The main difference between the 2 conditions is timing. Motor symptoms are common in people with early PD, and dementia may develop much later. In people with DLB, motor symptoms and dementia begin together or the dementia appears soon after movement symptoms. It can be hard for your doctor to tell if you have Parkinson's or DLB at the early stages of either condition.3,4


There is no one-size-fits-all answer to how cognitive changes will affect a person with PD or DLB. Each person will experience different symptoms and need to find what works best to manage these changes.1

After ruling out other causes of cognitive changes, your doctor may recommend medicine, occupational therapy, or speech therapy. Available drug therapies for PD are based on treatments used for Alzheimer’s disease. Occupational therapy might help you with ways to adapt and still carry out your ordinary activities. Speech therapy can help with language skills and how you process information.1

Some strategies that may help include:1

  • Keeping a written record of things to do each day
  • Simplifying tasks as much as possible
  • Breaking down tasks into smaller parts
  • Planning ahead as much as possible
  • Using aids like calendars, labels, and timers
  • Putting things in places where they will be easy to find
  • Taking breaks often to rest and relax

Caregiver impact

The caregiver impact of PD cognitive changes can be significant. Caregivers often report that they feel overwhelmed, stressed, and exhausted. They are usually the ones who start the conversations with doctors when the caregiver notices memory and thinking changes in their loved one.1

They may also find it difficult to manage their own lives while caring for a loved one with PD. Caregivers must take care of themselves and seek support from others. Many resources are available to help caregivers, including support groups and online forums.1

Cognitive changes can be frustrating and scary. But it is essential to remember that they are not always linked to dementia and a loss of independence. There are treatments available that can help improve thinking skills. With support from family and friends, people with PD can continue to live full and meaningful lives.1-3

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