Parkinson's Disease

Reviewed on 11/24/2021

What is Parkinson's Disease Dementia?

Parkinson's disease
Parkinson's disease is a fairly common age-related and progressive disease of brain cells (brain disorder).

Parkinson's disease (PD) is an age-related degenerative disorder of certain brain cells. It mainly affects movements of the body, but other problems, including dementia, may occur. It is not considered a hereditary disease, although a genetic link has been identified in a small number of families.

  • The most common symptoms of Parkinson's disease are tremor (shaking or trembling) of the hands, arms, jaw, and face; rigidity (stiffness) of the trunk and limbs; slowness of movement; and loss of balance and coordination.
  • Other symptoms include shuffling, speaking difficulties, (or speaking very softly), facial masking (expressionless, mask-like face), swallowing problems, and stooped posture.
  • The symptoms worsen gradually over years.

Depression, anxiety, personality and behavior changes, sleep disturbances, and sexual problems are commonly associated with Parkinson's disease. In many cases, Parkinson's disease does not affect a person's ability to think, reason, learn, or remember (cognitive processes).

  • In some people with Parkinson's disease, however, one or more cognitive processes are impaired.
  • If this impairment is severe enough to interfere with the person's ability to carry out everyday activities, it is called dementia. Fortunately, dementia occurs in only about 20% of people with Parkinson's disease.
  • If Parkinson's disease patients experience hallucinations and have severe motor control, they are at higher risk for dementia. The development of dementia is slow. Typically, people that develop symptoms of dementia do so about 10 to 15 years after the initial diagnosis of Parkinson's disease.

About 500,000 people in the United States have Parkinson's disease, and about 50,000 new cases are diagnosed each year. The number of those who have some cognitive symptoms is difficult to pinpoint because accurate data are lacking for the following reasons:

  • Researchers use various definitions of cognitive impairment and dementia.
  • Parkinson's disease often overlaps with other degenerative brain disorders that can cause dementia, such as Alzheimer's disease and vascular disease within the brain.
  • Some researchers suggest that at least 50% of people with Parkinson's disease have some mild cognitive impairment and estimate that as many as 20% to 40% may have more severe symptoms of dementia.

Most people have the first symptoms of Parkinson's disease after the age of 60 years, but Parkinson's disease also affects younger people. Early-onset Parkinson's disease strikes people around the age of 40 years, or even earlier.

  • Regardless of age at onset of the disease, dementia symptoms tend to appear later (after about 10 to 15 years) in the course of the disease.
  • Dementia is relatively rare in people with the onset of Parkinson's disease before age 50 years, even when the disease is of long duration.
  • Dementia is more common in people with older age (about 70 years) at the onset of Parkinson's disease.

What Are the Symptoms of Parkinson's Disease Dementia?

Cognitive impairment in Parkinson's disease may range from a single isolated symptom to severe dementia.

  • The appearance of a single cognitive symptom does not mean that dementia will develop.
  • Cognitive symptoms in Parkinson's disease usually appear years after physical symptoms are noted.
  • Cognitive symptoms early in the disease suggest dementia with Parkinsonian features, a somewhat different condition.

Cognitive symptoms in Parkinson's disease include the following:

  • Loss of decision-making ability
  • Inflexibility in adapting to changes
  • Disorientation in familiar surroundings
  • Problems learning new material
  • Difficulty concentrating
  • Loss of short- and long-term memory
  • Difficulty putting a sequence of events in the correct order
  • Problems using complex language and comprehending others' complex language

Persons with Parkinson's disease, with or without dementia, may often respond slowly to questions and requests. They may become dependent, fearful, indecisive, and passive. As the disease progresses, many people with Parkinson's disease may become increasingly dependent on spouses or caregivers.

Major mental disorders are common in Parkinson's disease. Two or more of these may appear together in the same person.

  • Depression: Sadness, tearfulness, lethargy, withdrawal, loss of interest in activities once enjoyed, insomnia or sleeping too much, weight gain or loss
  • Anxiety: Excessive worry or fear that disrupts everyday activities or relationships; physical signs such as restlessness or extreme fatigue, muscle tension, sleeping problems
  • Psychosis: Inability to think realistically; symptoms such as hallucinations, delusions (false beliefs not shared by others), paranoia (suspicious and feeling controlled by others), and problems with thinking clearly; if severe, behavior may be seriously disrupted; if milder, behavior that is bizarre, strange, or suspicious may occur.

The combination of depression, dementia, and Parkinson's disease usually means a faster cognitive decline and a more severe disability. Hallucinations, delusions, agitation, and manic states can occur as adverse effects of drug treatment of Parkinson's disease, this might complicate the diagnosis of Parkinson's dementia.

What Are the Causes of Parkinson's Disease Dementia and Is It Hereditary?

The causes of Parkinson's disease currently remain unclear; although about 10% are genetically linked, the remainder (approximately 90%), are of unknown cause. However, what is known is that clear evidence shows neuronal cells in an area of the brain known as the substantia nigra are altered and destroyed over time.

The current popular theory is that combinations of environmental and genetic factors are responsible for this neuronal cell alteration and destruction. The result of these interactions results in the loss of dopamine production, loss of neurons that make dopamine, loss of other neuron-generated substances, and the presence of Lewy bodies in brain cells, all of which are found at autopsy of Parkinson's disease patients.

The major components thought responsible for these changes are not clearly defined but include exposures to toxic environmental substances, oxidation of free radicals that damage cells, and their components (for example, generation of Lewy bodies from alpha-synuclein, a protein involved in neurotransmission), and mitochondrial dysfunction. People with certain gene combinations may be more likely to develop these alterations and have Parkinson's disease as a result.

Risk factors for dementia in patients with Parkinson's disease are as follows:

  • Age 70 years or older
  • Score greater than 25 on the Parkinson's disease rating scale (PDRS): This is a test that doctors use to check for the progression of the disease.
  • Depression, agitation, disorientation, or psychotic behavior when treated with the Parkinson's disease drug levodopa (Sinemet, Sinemet CR, Parcopa)
  • Exposure to severe psychological stress
  • Cardiovascular disease
  • Low socioeconomic status
  • Low education level

When Should I Call the Doctor About Parkinson's Disease Dementia?

Patient with Parkinson's disease warrants a visit to a health care professional with the following conditions:

  • Any significant change inability to think, reason, or concentrate;
  • in problem-solving;
  • in memory;
  • in the use of language;
  • in mood; or
  • in behavior or personality 

What Is Needed for a Parkinson's Disease Dementia Diagnosis?

There is no definitive medical test that confirms cognitive decline or dementia in Parkinson's disease. The most accurate way to measure cognitive decline is through neuropsychological testing.

  • The testing involves answering questions and performing tasks that have been carefully designed for this purpose. It is carried out by a specialist in this kind of testing.
  • Neuropsychological testing addresses the individual's appearance, mood, anxiety level, and experience of delusions or hallucinations.
  • It assesses cognitive abilities such as memory, attention, orientation to time and place, use of language, and abilities to carry out various tasks and follow instructions.
  • Reasoning, abstract thinking, and problem-solving are tested.
  • Neuropsychological testing gives a more accurate diagnosis of the problems and thus can help in treatment planning.
  • The tests are repeated periodically to see how well treatment is working and check for new problems.

Imaging studies: Generally, brain scans such as CT scans and MRIs are of little use in diagnosing dementia in people with Parkinson's disease. Positron emission tomographic (PET) scan may help distinguish dementia from depression and similar conditions in Parkinson's disease.

What Are the Treatments for Parkinson's Disease Dementia?

  • There is no cure for dementia in Parkinson's disease.
  • Rather, the focus is on treating specific symptoms such as depression, anxiety, and psychotic behavior.
  • A specialist in these disorders (psychiatrist) may be consulted for treatment recommendations.

What Is the Self-Care at Home for Parkinson's Disease Dementia?

Protein in the diet may affect the absorption of levodopa, the major medication used to treat Parkinson's disease. Fluctuations in the level of levodopa may worsen some behavioral and cognitive symptoms. A low-protein diet may reduce fluctuations in dopamine levels. In some patients with these fluctuations, dietary changes can improve symptoms. However, it is important to ensure that the person is getting adequate calories and other nutrients.

People with Parkinson's disease should remain as active as possible. Physical therapy helps the person maintain mobility.

In general, people with Parkinson's disease plus dementia should no longer drive vehicles. Movement problems may prevent quick reactions in hazardous driving situations. Certain medications, especially those given to treat symptoms of dementia, may make them less alert. However, this should be determined on an individual basis and in compliance with the laws of the state.

What Are Parkinson's Disease Dementia Medical Treatment and Medications?

There is no specific therapy for dementia in Parkinson's disease. Although cognitive symptoms initially may appear to respond to drugs that promote dopamine production, the improvement is mild and transient in contrast to the early responses to motor control improvement with medication in patients with Parkinson's disease.

Parkinson's disease dementia medications

Various medications are used to treat the movement disorders of Parkinson's disease, some may exacerbate symptoms related to dementia.

  • These include dopamine given in the form of levodopa; medications known as dopamine agonists (for example, a combination of carbidopa and levodopa known as Sinemet) that act on the dopamine receptor; and medications that slow down the metabolism of dopamine. They are often used in conjunction with monoamine oxidase inhibitors (MAO B,) such as rasagiline. In addition, anticholinergic drugs are sometimes used.
  • Unfortunately, these drugs may affect cognitive symptoms and mood disorders.
  • Anticholinergic drugs, for example, help balance levels of dopamine and acetylcholine, another neurotransmitter, in the brain. These drugs can improve movement disorders but often make memory loss worse.

The dementia of Parkinson's disease may respond to drugs used in patients with Alzheimer's disease. However, these drugs, called cholinesterase inhibitors (such as donepezil [Aricept], rivastigmine [Exelon], galantamine [Reminyl]), lead to only small and temporary improvements in cognition.

Mood disorders and psychoses are usually treated with other medication(s).

Parkinson's Disease Dementia Surgery and Gene Therapy

  • Great strides have been made in the surgical treatment of Parkinson's disease. Several different procedures are now available, and they are successful in many patients in relieving movement symptoms. Unfortunately, surgery has no effect on cognitive symptoms. In fact, most people with dementia are not candidates for surgery.
  • Gene therapy is in its infancy; there are ongoing human and animal trials with various methods (liposomes, viruses) to insert genes into neuronal cells to reduce or stop Parkinson's disease symptoms by causing cells to produce dopamine coded by the newly inserted genes. Early results with the treatment termed ProSavin (modified virus insertion) are encouraging. However, it is not clear if such therapy could prevent or reverse Parkinson's disease dementia.

Parkinson's Disease Dementia Follow-up, Prevention, and Prognosis

A person with Parkinson's disease and dementia requires regular checkups with his or her health care professional.

  • These checkups allow the health care professional to see how well treatment is working and make adjustments as necessary.
  • They allow detection of new problems of cognition, mood, or behavior that could benefit from treatment.
  • These visits also give the family caregiver(s) an opportunity to discuss problems in the individual's care.

Eventually, the person with Parkinson's disease and dementia will likely become unable to care for himself or herself or even to make decisions about his or her care if the patient lives long enough with Parkinson's disease and dementia.

  • It is best for the person to discuss future care arrangements with family members as early as possible, so that his or her wishes can be clarified and documented for the future.
  • A health care professional can advise patients and caregivers about legal arrangements that should be made to ensure that these wishes are observed.

Parkinson's disease dementia prevention

There is no known way of preventing dementia in Parkinson's disease. However, patients with Parkinson's disease are urged to continue to exercise and live a healthy lifestyle as this may delay or reduce the onset of dementia, although there is no good data to indicate this will occur.

Parkinson's disease dementia prognosis

Persons with Parkinson's disease and dementia have a poorer prognosis than persons with Parkinson's disease without dementia. Their risk of mood disorders and other complications, as well as premature death, is higher.

Support Groups and Counseling for Parkinson's Disease Dementia

If you are a person newly diagnosed with Parkinson's disease, you know that your disease has changed your life drastically. Not only are you losing some of your physical abilities, but you may be starting to lose some of your mental abilities as well.

You worry about how long you will be able to continue enjoying relationships with family and friends, activities you enjoy, and independence. You worry about how your family will cope with caring for you and themselves as your disease progresses. You may feel depressed, anxious, even angry and resentful. The best way to deal with these emotions is to express them in some way. For many people, talking about these feelings helps relieve them.

If you are a caregiver for a person with Parkinson's disease and dementia, you know that the disease may tend to be more stressful for the family members than for the affected person. Caring for a person with Parkinson's disease and dementia can be very difficult.

It often affects every aspect of life, including family relationships, work, financial status, social life, and physical and mental health. Caregivers may feel unable to cope with the demands of caring for a dependent, difficult relative. Besides the sadness of seeing the effects of your loved one's disease, you may feel frustrated, overwhelmed, resentful, and angry.

These feelings may in turn leave caregivers feeling guilty, ashamed, and anxious. Depression is not uncommon. Caregivers should seek support systems to help them adjust to the problems and feelings they may encounter.

Different people, both patients, and caregivers have different thresholds for tolerating these Parkinson's disease dementia challenges.

  • For many people with Parkinson's disease, talking to a close friend or family member may be helpful. For others, talking to a professional counselor or member of the clergy is comforting.
  • For caregivers, just "venting" or talking about the frustrations of caregiving can be enormously helpful. Others need more but may feel uneasy about asking for the help they need. One thing is certain, though: If the caregiver is given no relief, he or she can burn out, develop his or her own mental and physical problems, and become unable to care for the person with Parkinson's disease.

This is why support groups were invented. Support groups are groups of people who have lived through the same difficult experiences and want to help themselves and others by sharing coping strategies. Mental health professionals strongly recommend that affected persons, to the extent they are able, and family caregivers take part in support groups.

In diseases involving dementia, it is mainly the caregivers who are helped by support groups. Support groups serve several different purposes for caregivers:

  • The group allows the person to express his or her true feelings in an accepting, nonjudgmental atmosphere.
  • The group's shared experiences allow the caregiver to feel less alone and isolated.
  • The group can offer fresh ideas for coping with specific problems.
  • The group can introduce the caregiver to resources that may be able to provide some relief.
  • The group can give the caregiver the strength he or she needs to ask for help.

Support groups meet in person, on the telephone, or the Internet. To find a support group that works for you, contact the following organizations. You can also ask a trusted member of your health care team, or go on the Internet. If you do not have access to the Internet, go to the public library.

For more information about support groups, contact these agencies:

  • Parkinson's Alliance - (609) 688-0870 or (800) 579-8440
  • American Parkinson's Disease Association - (800) 223-2732
  • National Parkinson's Foundation - (305) 547-6666 or (800) 327-4545
  • Family Caregiver Alliance, National Center on Caregiving - (800) 445-8106
  • National Alliance for Caregiving -
  • Eldercare Locator Service - (800) 677-1116

Health Solutions From Our Sponsors

Reviewed on 11/24/2021