Can Parkinson's Disease Cause Dementia?

The same Lewy bodies in the brain that are suspected of causing Parkinson's disease are associated with several forms of dementia. The longer a patient has Parkinson's disease, the more likely they are to develop dementia. One study found that 78% of Parkinson's patients had developed dementia by the end of an eight-year period.

What Is Parkinson's Disease?

Parkinson's disease is a movement disorder that causes tremors, rigid muscles, and loss of control. It impacts the ability to walk, write, and even speak. Automatic movements such as blinking or smiling may become difficult. Because of the changes occurring in the muscles throughout the body, individuals with Parkinson's often display jerky arm motions, stooped posture, and blank facial expressions. 

Parkinson's disease gradually worsens with time, and it causes neurons in the brain to break down and die. These neurons produce chemical messengers known as dopamine and norepinephrine. When these chemicals are low or absent, the brain can no longer function properly. This results in a wide range of symptoms, including:

• Tremors
• Slurred speech
• Slowed movements 
• Depression, anxiety, and irritability
• Tiredness
• Constipation
• Bladder problems
• Pain and cramps in the muscles and joints

What Is Dementia?

Dementia itself isn't a disease but the result of another condition. Memory loss is one of the most noticeable signs of dementia. However, one can experience memory loss without having dementia. The loss of cognitive function that's formally known as dementia is associated with a wide range of symptoms, such as:

• Confusion
• Poor judgment
• Trouble speaking or finding words
• Getting lost in familiar areas
• Hallucinations
• Difficulty organizing or planning
• Paranoia
• Agitation
• Changes in personality

Alzheimer's is one of the best-known diseases associated with dementia, but people can experience dementia for many reasons. 

The Relationship Between Parkinson's and Dementia

Severe memory and thinking problems in patients with Parkinson's are often indicative of Parkinson's disease dementia (PDD), which is similar to Lewy body dementia (LBD). Both forms of dementia occur when protein clumps known as Lewy bodies build up in the brain. In Parkinson's patients, the Lewy bodies initially collect around the basal ganglia, which controls movement.

Over time, the Lewy bodies can spread to other parts of the brain where they impact cognitive function. Patients are more likely to suffer from PDD if they have had Parkinson's disease for a long time. However, PDD doesn't occur in all patients. In fact, dementia impacts just 16 to 20% of patients aged 60 to 75 who have had Parkinson's disease for five to 10 years. In the same age group, this increases to as much as 30% among those who have had Parkinson's for 10 to 15 years. 

Parkinson's patients are more likely to develop PDD if they have severe motor symptoms that impact both sides of the body. Postural instability and gait disturbance (PIGD) is more common in people with PDD. PIGD is a pattern of movement that includes shuffling, pausing in the middle of a step, and struggling to initiate movement. Rapid eye movement sleep behavior disorder and problems with the autonomic nervous system also increase the likelihood of PDD. 

Distinctive Features Between Parkinson's Disease and Other Forms of Dementia

PDD and LBD are nearly indistinguishable based on the symptoms alone. The key factor in PDD is the presence of Parkinson's disease well in advance of the dementia symptoms. A patient must have been diagnosed with Parkinson's disease at least a year before the onset of dementia symptoms for the condition to be considered PDD. If the dementia occurs before or concurrently with Parkinson's disease, it's diagnosed as LBD.

For some patients, mild cognitive impairment (MCI) precedes PDD. MCI is a slight decline in mental abilities that impacts memory, judgment, and reasoning. It's more difficult to plan and complete everyday tasks with MCI, but the impact isn't as severe as that of PDD. About 10 to 20% of Parkinson's patients experience MCI at some point in the course of the disease.

PDD is typically less disabling than dementia associated with Alzheimer's. Alzheimer's patients cannot form new memories, while those with PDD can retain this ability. Alzheimer's patients also experience language problems earlier than those with PDD.

The Role of Caregivers in Managing PDD

Some medications may help ease the symptoms of PDD. A professional caregiver can pick up prescriptions and provide medication reminders to ensure patients stay on schedule and don't miss a dose. PDD patients often struggle to stay organized or plan. Caregivers can step in and assist with meal planning, shopping, and housekeeping tasks.

Caregivers can also help PDD patients by making changes to their environment. PDD patients often struggle to find items in a cluttered space. Maintaining a neat and organized living space will make it easier for PDD sufferers to navigate their surroundings. Well-trained caregivers can also provide social and emotional support.

Find the Right Caregiver at Visiting Angels of Western North Carolina

Our in-home caregivers can provide support for PDD while allowing patients to age comfortably in place at home. If you're interested in scheduling care and support for yourself or a loved one, contact us at Visiting Angels of Western North Carolina in Asheville, North Carolina, for a complimentary consultation to learn more about how we can help.