Dementia Due to Parkinson’s Disease

Dementia Due to Parkinson’s Disease

Although dementia rarely occurs as an initial symptom of Par-kinson’s disease, it is found in nearly 40% of such patients older than 70 years of age. Approximately 1 million people in the USA have the disease, with 50 000 new cases being diagnosed each year. The prevalence for persons over 60 is 1%. The disease re-sults from loss of dopamine production in the basal ganglia, and can be idiopathic or postencephalitic. Usually the patient is 50 years of age or older, and unlike Alzheimer’s and Pick’s demen-tias, this disease occurs slightly more often in men (Berg et al., 1994). Dementia most commonly occurs in cases of Parkinson’s disease in which the decline has been rapid and response to anti-cholinergics has been poor.

The pathology of Parkinson’s disease involves depigmen-tation of the so-called pigmented nuclei of the brain (locus coer-uleus, substantia nigra). These nuclei then contain eosinophilic Lewy bodies. As in Alzheimer’s disease the cerebral cortex of many of these patients contains many senile plaques and neurofi-brillary tangles, loss of neurons, and decreased concentrations of choline acetyltransferase. Patients with parkinsonian dementia also have reduced choline acetyltransferase in the cerebral cortex and substantia nigra.

The clinical features of Parkinson’s disease are well described, with the cardinal triad being tremor, rigidity and bradykinesia. Associated features include postural instability, a festinating gait, micrographia, seborrhea, urinary changes, con-stipation, hypophonia and an expressionless facial countenance. The tremor in Parkinson’s disease has a regular rate and is most prominent when the patient is sitting with arms supported; it has therefore been described as intention tremors. Paranoid delusions and visual hallucinations may occur, but auditory hallucinations are rare. Antipsychotics with low incidence of extrapyramidal symptoms such as quetiapine, olanzepine, and ziprasidone are The pharmacological treatment of Parkinson’s disease recommended. involves the use of a number of types of medication and ziprasidone are recommended. These in-clude selegiline a selective monoamine oxidase inhibitor, levo-dopa, other dopamine agonists (pramipexole, bromocriptine, pergolide mesylate, amantadine), and various anticholinergic agents (benztropine). Selegiline should not be given to patients on antidepressant medication as there is a risk that dopaminergic agents may activate psychosis or mania and that anticholinergic drugs may increase confusion. When discontinuing levodopa after a long course of treatment, the drug should be tapered so as to prevent a discontinuation syndrome similar in nature to the neuroleptic malignant syndrome. Some medications (metoclo-pramide, droperidol, several antipsychotics) may produce par-kinsonian features such as masked facies, sparsity of speech and tremor, and in those cases the appropriate course of treatment is to discontinue the offending medication. Several researchers are looking into the possibility of using embryonic stem cells implants as treatment for Parkinson’s disease and several other conditions.