Rivastigmine and Parkinson dementia complex.

Patients suffering from Parkinson's disease dementia (PDD) have a movement disorder, but it can be difficult to determine whether the functional impairment, which is critical in making the assessment of whether a patient has achieved the threshold for a diagnosis of dementia, is due to the dementia or the underlying Parkinson's disease. Although the cognitive impairment found in nondemented patients with Parkinson's disease is very dysexecutive in nature, the DSM IV (Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association IV) diagnosis of PDD has memory impairment as the defining characteristic of PDD. Severe deficits in cortical, cholinergic, excitatory, neuromodulatory input mean that memory impairment is not always due to encoding and retrieval strategy deficits, but it may also be amnesic without being related to concomitant Alzheimer's disease pathology. Patients with PDD have a high mortality, especially when they develop hallucinations and/or are admitted to nursing homes. Of interest is the reduction in mortality that was more marked in the subgroup with visual hallucinations at baseline. The increased mortality in PD may be due to autonomic failure, evidenced by the reductions in heart rate variability in these patients. This reduction is greater in patients with hallucinations. Rivastigmine is a dual inhibitor of brain acetyl- and butyrylcholinesterases that has been evaluated in the symptomatic treatment of patients with mild-to-moderate dementia associated with idiopathic Parkinson's disease. Although there is a need for more studies using pragmatic measures, such as time to residential care facility and both patient and carer quality of life assessments, rivastigmine appears to improve cognition and activities of daily living in patients with PDD, resulting in a clinically meaningful benefit in a large number of cases.