ARTICLE #6: NOT JUST A MOVEMENT DISORDER: COGNITIVE CHANGES IN PARKINSON'S DISEASE (PD)
Reprinted with the permission of the Parkinson's Disease Foundation

Language dysfunction:

The most common language- related difficulty for people with PD is word finding. As a person's PD progresses, he or she may also experience problems with naming or mis-naming, may have difficulty comprehending complex information, and may use more simplified and less spontaneous speech.

Visual-spatial disturbances:

Trouble perceiving, processing, discriminating, and acting on visual information in the environment can affect daily life. For example, it may become difficult to navigate around the house or estimate distances when reaching for something, thereby increasing the risk of falls. In some cases, visual-spatial impairment in PD may also lead to visual misperceptions, or illusions.

Causes of Cognitive Changes in PD

Our understanding of the causes of cognitive changes in PD is incomplete. We do know that problems with cognition are related to the same underlying brain changes that result in motor symptoms - that is, premature death of nerve cells, changes in brain neurochemistry, and subsequent alterations in brain circuitry between different brain regions. In addition, Lewy bodies, the abnormal collections of proteins that are found in nerve cells in PD, are related to changes in motor pathways and to pathways affecting cognitive processes. Other elements can cause and aggravate cognitive changes. Untreated depression, anxiety, psychosis, sleep, and other behavioral difficulties can exacerbate cognitive difficulties. Also, some medications, whether for PD or other conditions, can cause negative cognitive effects as can some non-PD related general medical conditions, such as infections.

Treatment of Cognitive Changes in PD

The basis of all effective treatment is a thorough diagnostic evaluation. When an initial history is taken, by a primary care physician or a neurologist, it is important for a person with PD (and his or her caregiver) to bring up any observations or concerns about cognitive changes. Referral to a neurologist, neuropsychiatrist, or geriatric psychiatrist who specializes in the treatment of cognitive problems or dementia can be helpful. Additional tests may also be conducted to ascertain if a person's difficulties are due to PD or to other reversible causes. Once other causes are excluded, a neuropsychological exam, involving paper-and-pencil tests, will be performed by a neuropsychologist to characterize the quality and extent of problems and to identify areas of strength.

Treatments for cognitive changes aim to reduce symptoms or improve daily life through using compensatory strategies (ie. coping mechanisms that help a person adapt to his or her cognitive imitations). For instance, clocks or timers may help a person remember when to take medication, and devices such as planners or voice recorders may help him or her recall an appointment. Occupational therapists can also assist, by providing insights into how cognitive difficulties impact daily life, suggesting adaptive strategies, or providing formal treatment programs. Speech therapists can help with language functions and information processing. Medications used to treat cognitive dysfunction in Parkinson's are largely based on treatments used for Alzheimer's disease and are usually reserved for these patients who already have dementia. At present, rivastigmine (Exelon ® ) is the only medication approved by the US Food and Drug Administration for the treatment of dementia in PD. Further research is needed to identify treatments that can help those who experience less severe cognitive impairments that occur earlier in the course of PD.

Conclusions

Cognitive changes are present to some degree in almost every person with PD and are a prominent feature of PD over its course. Although they have received less attention than motor symptoms, cognitive changes have obvious effects on daily life, including how people adapt to their motor symptoms. While we do not yet have definitive treatments for cognitive dysfunction in PD, recognition of what changes have occurred is important in order to take advantage of currently vailablemedication and behavioral strategies.

Laura Marsh, M.D., is a geriatric psychiatrist, an Associate Professor of Psychiatry and Neurology at Johns Hopkins University School of Medicine, and director of the Clinical Research Program of the Johns Hopkins Morris K. Udall Parkinson's Disease Research Center of Excellence.

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© 2008 Parkinson's Disease Foundation

If you have or believe you have Parkinson's disease, then promptly consult a physician and follow your physician's advice.

This publication is not a substitute for a physician's diagnosis of Parkinson's disease or for a physician's prescription of drugs, treatment or operations for Parkinson's disease.