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Psychiatric Adverse Effects Estimates of the prevalence of dementia in Parkinson's disease vary widely, but is most commonly placed in the 15%-20% range. The prevalence of dementia in Parkinson's disease is key in assessing potential psychiatric effects of levodopa. Levodopa's most common psychiatric adverse effects can take a variety of forms, including confusion, agitation, visual hallucinations, paranoia, psychosis, and hypersexuality. The emergence of these adverse effects can compromise drug therapy, since a levodopa dose reduction may be necessary.3,6 Nocturnal Phenomena Psychiatric effects induced by levodopa will sometimes present initially as nocturnal phenomena, such as vivid dreams, nightmares, disturbed sleep patterns, and visual hallucinations. Improvement can occasionally be achieved by reducing or stopping the last evening dose or giving the last dose earlier in the evening.1,8 Levodopa-induced psychiatric effects are believed to be progressive.3 As a result, experts differ as to whether visual hallucinations that are not accompanied by distress require a prompt decrease in the levodopa dosage. Frequently, a compromise must be reached between some hallucinations and suboptimal control of symptoms. Psychotic Symptoms Pharmacodynamic changes from age-related changes in the brain-such as reduced cerebral blood flow, increased permeability of the blood-brain barrier, and increased conduction time-may be responsible for greater sensitivity to centrally-acting drugs.8 As a result, elderly patients are more vulnerable to psychosis. The emergence of psychotic symptoms requires a review of all potentially causative medications. The medications with the greatest potential for inducing psychosis but lesser effects on parkinsonian symptoms should be discontinued first. For example, anticholinergic agents should be discontinued first, followed by selegiline, amantadine, and, finally, dopamine agonists. If a patient is not receiving any of these medications or if withdrawal of these agents is not effective, then a reduction in the levodopa dosage should be considered.6 Use of neuroleptic agents must be considered if the levodopa dosage reduction results in intolerable parkinsonian symptoms (Table 3). Certain neuroleptic agents, such as haloperidol and chlorpromazine, are contraindicated because they block both limbic and striatal dopamine receptors and aggravate parkinsonian symptoms. Less potent neuroleptic agents, including thioridazine11 or molindone,12 may be considered for use, but their effectiveness is limited. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.408 / Virus Database: 230 - Release Date: 10/24/2002 ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn