Parkinson’s disease (PD) dementia is a condition that some people can experience after living with PD for some time. It is often difficult to accurately diagnose the precise form of dementia a person may have and differentiate PD dementia from Lewy body dementia and Alzheimer’s disease.

Talking about dementia can be frightening, but it is very important to remember that not everyone with PD will experience cognitive changes. While over half of people diagnosed with PD do experience a degree of cognitive decline, not all among these go on to develop dementia. As will all symptoms of PD, everyone is different.

 

Cognitive Decline and Dementia

Cognitive decline includes difficulties with attention, task completion, decision-making, problem solving, memory, and word-finding. These symptoms can be very frustrating and annoying, but may not have a serious impact on one’s daily life in the early stages.

Dementia is described as a profound decline in the cognitive challenges listed above to the point where they have a significant impact on functioning and daily life. Dementia also represents a dramatic change for carepartners and families to cope with.

Both cognitive decline and dementia are some of the most common non-motor symptoms of PD (Biundo et al., 2016). Individuals with PD experiencing mild cognitive decline are six times more likely to develop Parkinson’s dementia than the general population, and while up to 80% of people with PD do develop dementia, it is usually after decades of living with the illness (Biundo et al., 2016).

Researchers still do not know precisely what causes Parkinson’s disease dementia, but it is thought to be related to build-up in the brain of a protein called alpha synuclein. Eventually, this protein forms clumps, which are called Lewy bodies; these clumps disrupt normal brain cell function, leading to cell death and symptoms of dementia (Weill Institute for Neurosciences, n.d.).

Parkinson’s dementia can potentially have a greater impact on social and occupational functioning compared to Alzheimer’s disease due to the combination of motor and cognitive impairments. Development of dementia in Parkinson’s represents progression of the disease, usually after many years of motor impairment.

Symptoms of PD dementia include:

  • forgetfulness
  • slow thought process
  • difficulty concentrating and fluctuating attention
  • difficulty with word-finding and communication
  • difficulty with decisions, planning, and problem-solving sleep disturbances, such as being alseep during the day and up at night (called sleep/wake cycle disturbance) or REM behaviour disorder, which results in acting out dreams (Weill Institute for Neurosciences, n.d.)
  • hallucinations
  • paranoia
  • depression and/or anxiety

Parkinson’s disease dementia can also cause small problems with how you see things. This might make you think you are seeing things that aren’t there or have trouble finding items in a crowded place. It can also make it hard to get around places you know or don’t know well. When it’s dark or if your eyes have problems like macular degeneration, these issues might worsen (Parkinson’s Foundation, n.d.).

 

Lewy Body Dementia

The diagnosis of Lewy body dementia is made when cognitive and thinking problems appear before or at the same time as the onset of motor symptoms of PD. The symptoms specific to Lewy body dementia can include all of those common in PD dementia, as well as memory problems, slowness of movement, and other PD symptoms.

 

Alzheimer’s Disease

Alzheimer’s is a form of dementia relating to the development in the brain of substances known as “plaques”, which are toxic to neurons, and “tangles”, which interfere with vital processes, eventually choking off the living cells.

The symptoms of Alzheimer’s include:

  • memory loss that disrupts daily life
  • difficulty planning and finishing tasks
  • confusion and disorientation
  • apathy and depression
  • behavioural changes
  • difficulty speaking

 

Treatments for Dementia

While there is no cure for Parkinson’s disease dementia or Lewy body dementia, medications can help ease symptoms, especially those used in Alzheimer’s disease. A particular class of medication called cholinesterase inhibitors are effective at managing memory problems, and sleep issues can be helped by taking supplements like melatonin (Weill Institute for Neurosciences, n.d.).

Some individuals with PD dementia experience hallucinations. Fortunately, most hallucinations tend to be harmless and do not require treatment. However, for those that do, it is important to discuss any medication changes with a doctor or neurologist, as many medications that can help hallucinations may result in worsening of motor symptoms (Weill Institute for Neurosciences, n.d.). It is important to bring an accurate list of symptoms of cognitive decline and/or dementia with you to your neurologist, and, if possible, a carepartner, friend, or family member should be present with you during your appointments.

 

Additional Resources

Lewy Body Dementia Association | www.lbda.org

Alzheimer Society British Columbia | www.alzheimerbc.org

 

Sources

Biundo, R., Weis, L., & Antonini, A. (2016). Cognitive decline in Parkinson’s disease: the complex picture. npj Parkinson’s Disease, 2, 16018. https://doi.org/10.1038/npjparkd.2016.18

Parkinson’s Foundation (n.d.). Dementia. https://www.parkinson.org/understanding-parkinsons/non-movement-symptoms/dementia

Weill Institute for Neurosciences (n.d). Parkinson’s Disease Dementia. https://memory.ucsf.edu/dementia/parkinsons/parkinson-disease-dementia 


Last updated: December 12, 2023