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Understanding Parkinson’s Disease Dementia

According to the National Institutes of Health, approximately 500,000 people in the U.S. have been diagnosed with Parkinson’s disease (PD), and that number is expected to double by 2040. Many of these patients have no cognitive impairment; others develop mild cognitive impairment, which does not affect their ability to perform daily tasks independently. But an estimated one-fourth of patients diagnosed with PD develop Parkinson’s disease dementia (PDD), according to Jumana Alshaikh, MD, neurology specialist and co-director of the Parkinson’s Disease Center of Excellence at University of Utah Health and assistant professor in the neurology department.

“For some patients, their cognitive impairment progresses to a point where they have dementia,” Alshaikh explains, “meaning that their cognitive symptoms affect their ability to be independent and they need help from others for their day-to-day tasks.” 

According to an article in the Journal of Neurological Sciences, dementia is more likely for patients who have been living with PD for more than 10 years. Additionally, Alshaikh said that patients who are diagnosed with Parkinson’s at an older age are more at risk for PDD. “Also, the more advanced and severe your other Parkinson’s symptoms are, the more at risk you are to develop PDD,” she says. 

PDD Symptoms

Patients who develop PDD experience impairments in different areas of cognition. More prominently, these impairments occur in executive and visuospatial functions and attention, which include difficulties planning, organizing, dressing, driving, and multitasking. Although PDD patients may experience forgetfulness—a hallmark of Alzheimer’s disease—it is often due to disorganization of thoughts, Alshaikh says, and patients might be able to recall things when provided clues. Patients with PDD can also develop other symptoms such as hallucinations and delusions. 

How Is PDD Diagnosed?

PDD is diagnosed after the patient has an established diagnosis of Parkinson’s disease and develops cognitive symptoms that start after at least one year from the time that movement symptoms of Parkinson’s began. In order for the cognitive impairment to be called dementia, it must be severe enough that the patient requires assistance from others to complete their daily activities. 

“We base this information from the history provided by the patient and their caregivers,” Alshaikh says, “and then we perform cognitive assessments with an office-based cognitive test such as the MoCA (Montreal Cognitive Assessment). If further information is needed, we may perform additional testing, refer the patient to a neuropsychologist for more detailed cognitive assessments, or order imaging studies such as an MRI brain or PET scan to rule out other causes of dementia.” 

Treatment for PDD

Medications can help treat PDD. These medications boost levels of acetylcholine, a chemical in the brain that is involved in cognition and memory. Increasing the levels of acetylcholine can even help with hallucinations related to Parkinson’s. Some patients with severe hallucinations may also need anti-psychotic medications, though Alshaikh recommends caution about which of those medications can be prescribed. Some of those medications need to be avoided since they can worsen the movement symptoms associated with Parkinson’s.

Medications only alleviate the symptoms of PDD. However, they don’t reverse the underlying disease process or slow down what’s happening in the brain. But some studies suggest exercising regularly—"especially exercises that get your heart rate up,” Alshaikh says. “Aerobic exercises or cardio exercises might have an effect on slowing down the progression of Parkinson’s disease. In addition to that, exercise can also improve cognition and memory.” 

Physical activity must be tailored to the patient’s abilities and movement issues associated with Parkinson’s disease, which is why it’s ideal to set up an exercise program with a physical therapist. 

Additionally, it’s important to look at other things that might contribute to the patient’s cognitive symptoms. “For example, poor sleep quality can make cognition worse since sleep plays an important role in the consolidation of our memories,” Alshaikh says. Problems like anxiety or depression and hearing impairment can also worsen cognition. 

Tips for Caregivers

Alshaikh has these suggestions for caregivers:

  • Encourage your loved one with PDD to exercise regularly and engage in activities that they enjoy.
  • Be present for medical appointments so that you can provide important collateral information to their doctors that can help with their treatment. 
  • Get involved with helping your loved one implement the treatment plan discussed with their doctor. 
  • Try to create an environment or opportunities for social interaction. 
  • Be patient as a Parkinson’s patient may be slower to respond to questions. Don’t assume that because they take a long time to answer, they don’t know the answer to a question. 
  • Regularly review the patient’s medications with their neurologist to see whether medications are making cognition worse—these could be medications given for other routine medical conditions. 

If cognition declines rapidly or suddenly and your loved one or patient becomes much more confused than normal, seek medical attention right away as a medical problem such as a urinary tract infection could be exacerbating the PDD symptoms.

Caregivers are often unprepared for many of the tasks and challenges they will face. Educating yourself and practicing self-care are important tools for success. You can find valuable information and advice online at the Parkinson’s Foundation, the National Council on Aging, and the National Caregiver Alliance websites.