Memory and thinking problems are among the most worrisome Parkinson's symptoms. Given the significant impact on function and quality of life, understanding and treating the range of cognitive changes in Parkinson's is a top priority for researchers.
Memory and thinking (also known as cognitive) symptoms are common in Parkinson's, but not everyone experiences them. In some people, they are mild and don't impact work or daily activities. This is "mild cognitive impairment." In others, they are more significant and impact both the everyday activities of the person and their care partner. This is "dementia." There are many different aspects of memory and thinking, and people with Parkinson's most commonly notice difficulty with:
- paying attention or concentrating
- problem solving
- interpreting where objects are in space
- remembering information for short periods
If you or your loved one notice memory or thinking changes, tell your doctor about your concerns. Your doctor may first ask if you have other Parkinson's symptoms, such as depression or anxiety, sleep problems or fatigue, which can impact cognition. These symptoms require different evaluations and treatments. The doctor also will review your medications — both prescription and over-the-counter — to ensure these aren't contributing to cognitive changes. Parkinson's medications, such as Artane (trihexyphenidyl), for example, can cause confusion as a side effect.
No brain imaging or blood tests can specifically diagnose cognitive changes associated with Parkinson's disease. But doctors may order these to look for other conditions, such as low thyroid or vitamin B12, which can affect cognition. Your doctor likely will do a few simple memory tests (asking you to remember three objects, repeat a sentence, etc.) and in some cases may recommend detailed memory and thinking tests. These tests can help determine what problems are present and whether they are due to Parkinson's or another condition.
Mild Cognitive Impairment
Mild cognitive impairment (MCI) is a memory or thinking change that is more than what is expected with normal aging but is not enough to impede daily activities. People with MCI may feel distracted or disorganized or lose their train of thought. They might find it more challenging to concentrate or manage multiple projects at work.
Unfortunately, at this time no medications are FDA-approved to treat MCI. Treatment consists of memory tools, such as notes to yourself, calendars and to-do lists, and behavioral strategies, such as always keeping your keys in the same location. Your doctor also may recommend cognitive rehabilitation, a type of therapy in which you learn memory exercises and techniques to manage memory and thinking changes.
Mild cognitive impairment can, but doesn't always, progress to dementia.
Parkinson's Disease Dementia
Dementia is a general term for a change in memory, thinking and/or language abilities that is severe enough to interfere with daily routines, job performance or social interactions. If Parkinson's disease dementia (PDD) occurs, it tends to be much later in the course, after a decade or so of living with disease.
People with PDD may experience many of the same symptoms as those with mild cognitive impairment, but more significantly. They may have difficulty planning and completing activities and may take longer to process information and respond to questions. Those with PDD may have trouble finding words, experience short-term memory loss and become confused about their surroundings. PDD also can cause changes in mood, behavior and motivation. In some cases, it may be associated with visual hallucinations (seeing things that aren't there) or delusions (false, often paranoid, beliefs).
Since there is no specific test to diagnose dementia, it may be hard to differentiate PDD from Alzheimer's disease or dementia with Lewy bodies (DLB). Alzheimer's typically causes more significant memory loss and confusion, and lacks Parkinson's motor symptoms, although stiffness and slowness may develop in late stages. DLB, a form of atypical parkinsonism, includes dementia and Parkinson's motor symptoms, as well as visual hallucinations and shifting levels of alertness. In DLB, dementia usually starts at the same time or within a year of Parkinson's motor symptoms.
Medication may ease the symptoms of Parkinson's disease dementia, but unfortunately it can't slow progression. Exelon (rivastigmine) is approved by the U.S. Food and Drug Administration (FDA) for mild to moderate PDD. It increases the brain chemical acetylcholine, which supports memory and thinking. Exelon may improve cognition; lessen behavioral changes, such as agitation; and delay the need for alternative living situations, such as a long-term care facility. In some situations, doctors may instead prescribe other medications that work similarly. Aricept (donepezil), which is FDA-approved for Alzheimer's disease, is one example.
Researchers don't know exactly why memory and thinking problems happen in Parkinson's, but brain chemical and brain cell changes likely play a role. Parkinson's affects several brain chemicals, including dopamine, acetylcholine and norepinephrine, that are important for cognition. The disease also causes loss of or changes to brain cells that support memory, thinking and attention.
Keeping a Healthy Brain
No medication or activity has yet been proven to prevent cognitive changes, but researchers are examining several avenues. There is much you can do to maintain a healthy body and lifestyle, which likely promote a healthy brain. These include exercising your body and brain regularly, eating a balanced diet and staying socially engaged. You can keep your mind active by practicing mental challenges: anything from doing a crossword or jigsaw puzzle to learning a foreign language to playing a new instrument. Attending a social gathering allows you to interact with others while exercising your brain — you can meet new people, practice remembering names and make conversation about current events.
Researchers are working to understand more about cognitive changes in Parkinson's, and develop treatments to target mild cognitive impairment and dementia. Investigators are testing novel medications, cognitive and physical exercises, and brain stimulation for benefit in Parkinson's. They also are looking for tools, such as rating scales, and measurements, such as brain scans, to better diagnose these conditions and differentiate Parkinson's disease dementia from Alzheimer's and dementia with Lewy bodies. The Michael J. Fox Foundation supports work in this high-priority area, and is building inroads with regulators to ensure the right scales are being developed to properly evaluate benefits of cognitive therapies.