Cognitive impairment severe enough to interfere with everyday activities and functions. Dementia includes dysfunctions of memory, logic, reasoning, and analytical thinking. agitation, anxiety, and problems with memory and language (such as difficulty in finding the right words) are often the earliest signs of dementia. delirium, delusions, hallucinations, paranoia, and sleep disturbances often are present later in dementia. The degree to which dementia is apparent fluctuates, particularly early on, when the person might have extended periods of normal cognitive function with infrequent and minor interruptions of cognitive impairment. Because these inconsistencies are unpredictable, managing them is more difficult than managing symptoms of dementia that is constant. However, dementia represents progressive degeneration of brain function and gradually worsens with time.
The older the person with Parkinson’s, the more likely that dementia will develop or already is present. This is likely an interaction of the progression of the Parkinson’s and the deteriorations that occur with aging. in a person who already has dementia at the time Parkinson’s disease is diagnosed, treatment with dopaminergic medications such as amantadine and selegiline or with dopamine agonist medications such as pergolide and bromocriptine is likely to worsen the dementia. anticholinergic medications such as benztropine, trihexyphenidyl, and biperiden, prescribed to relieve tremors, can worsen cognitive impairment overall, further contributing to dementia.
Those who are closest to the person, such as family members, friends, and caregivers, typically notice the signs of dementia although the person with Parkinson’s does not. A health care provider can gather some idea as to the presence and extent of dementia by using a tool called the mini-mental status examination (MMSE), a short series of questions that gauge the person’s orientation to time and place as well as ability to use language, follow multistep directions, and perform analytical tasks such as sequentially subtracting or adding numbers.
There are several forms of dementia that can accompany Parkinson’s disease. There is some debate as to how dementia and Parkinson’s are related.
Some researchers believe that dementia exists independently but concurrently with Parkinson’s. others believe that there is an overall connection between dementia and various neurodegenerative conditions including Parkinson’s disease as well as alzheimer’s disease.
Lewy Body Dementia
The lewy body is a deposit of proteins, particularly alpha-synuclein, within a neuron that has a characteristic shape and structure. These deposits, which so far can only be detected at autopsy, are not present in the brain of people without neu-rodegenerative conditions but are typically found in the brain of people with Parkinson’s disease. They are virtually restricted to the substantia nigra and other structures of the midbrain and basal ganglia in people with Parkinson’s. In people with Parkinson’s who develop dementia later, Lewy bodies are usually present in other parts of the brain as well. Some people who have dementia long before the onset of parkinsonian motor features also have Lewy bodies present in regions of the brain responsible for cognitive function but not in those related to movement. These people are said to have Lewy body dementia.
A number of researchers believe that Parkinson’s disease and dementia are both Lewy body disorders and that the symptoms reflect the areas of the brain where Lewy bodies exist. When both motor and cognitive symptoms are present, these researchers refer to the condition as diffuse lewy body disease. However, a person with Parkinson’s disease can have Lewy body dementia or non-Lewy body dementia. Because there is no way as yet to determine the presence or absence of Lewy bodies in a living person, these distinctions remain incompletely understood.
People who have Lewy body dementia tend not to tolerate the conventional medications, such as antipsychotic and antianxiety medications, that are sometimes effective in other forms of dementia. These drugs act to inhibit the brain’s dopamine receptors, thereby increasing motor symptoms such as tremor and bradykinesia. Two of the acetylcholinesterase inhibitor drugs currently available to treat cognitive impairment in Alzheimer’s disease that sometimes help are rivastigmine and donepezil. Rivastigmine has been proven effective in Lewy body dementia in several studies, including a randomized controlled trial, and does not worsen the motor symptoms of Parkinson’s. Donepezil’s usefulness in Lewy body dementia is supported by at least one open label trial, though there are some reports of it worsening parkinsonian motor symptoms. Galantamine has been reported to help in a number of cases. Tacrine has been reported to help in few cases, but it has been more frequently reported to harm motor function. Two atypical antipsychotic drugs, so called because they have different mechanisms of action from conventional antipsychotic drugs, that sometimes reduce dementia symptoms in Lewy body dementia and dementia in Parkinson’s are quetiapine (Seroquel) and clozapine (Clozaril).
Alzheimer’s Dementia
Deterioration of cognitive function is a recognized natural dimension of aging. Estimates project that beyond age 85, most people have some level of dementia. So-called age related dementia is usually Alzheimer’s disease. The dementia of Alzheimer’s disease has different characteristics from those of Parkinson’s disease but often coexists with Parkinson’s. Experts estimate that as many as a third of those who have one of these diseases also have the other. Rather than Lewy bodies, protein deposits called amyloid plaques accumulate and interfere with neuron communication in Alzheimer’s disease. The dementia of Alzheimer’s is less variable and more obviously progressive than the dementia of Parkinson’s and has predictable patterns of ebb and flow such as sundowning, or the worsening of dementia symptoms toward the end of the day.
Anticholinergic medications used as adjunct therapies for Parkinson’s disease can worsen the dementia of Alzheimer’s disease as they further inhibit the actions of acetylcholine, which is already in short supply in Alzheimer’s. A recent report even hints at links between the use of these anticholinergic medications in people with Parkinson’s and an increase in the risk of developing Alzheimer’s. Acetylcholinesterase inhibitors often diminish the symptoms of dementia in Alzheimer’s disease.
Multiinfarct Dementia
Multiinfarct dementia is cognitive impairment that is the result of damage from strokes or small vessel ischemic changes. it typically progresses in a stepwise fashion as more infarcts (strokes) occur. These infarcts are the result of either progressive narrowing of vessels from atherosclerosis such that they eventually plug up (occlude), or from small clots having broken loose from other parts of the body making their way to the brain, where they lodged inside the arteries, disrupting the flow of blood to a portion of the brain. The location of the infarct, or clot and blockage, determines the nature and extent of the damage, which generally is small but becomes cumulative. sometimes this form of dementia shows up on a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the head. The only value in knowing that the dementia is the result of multiple infarctions is that treating the underlying cause, which is commonly hypertension, may be possible. Drugs such as those taken for the dementia of Alzheimer’s disease are not effective in multiinfarct dementia. Anti-Parkinson’s medications have no effect on multiinfarct dementia; however, it is not always easy to determine that multiinfarct dementia is the form of dementia present. .
