New guidelines issued for Parkinson's disease

July 24, 2006

At the American Academy of Neurology's (AAN) 58th annual meeting in April, new guidelines were released for the diagnosis and treatment of Parkinson's disease (PD). The recommendations were later published in the April 11, 2006, issue of Neurology as four separate practice parameters.

Previous guidelines, published in 2002, focused on which medications were best as patients started to develop symptoms of PD, said author William J. Weiner, M.D., FAAN, University of Maryland School of Medicine. The new recommendations offer a more comprehensive view of PD and address issues of psychological co-morbidities, common symptoms of the disease that are often left untreated, he explained.

In the Neuroprotective Strategies and Alternative Therapies in Parkinson Disease parameter, the Quality Standards Subcommittee (QSS) of the AAN determined that there is currently no treatment that is neuroprotective in PD. The group also determined that levodopa does not appear to accelerate disease progression, a concern that some people had due to an increased incidence of dyskinesias that occurs following high doses of the drug.

In addition, the QSS found that pergolide, pramipexole (Mirapex, Boehringer Ingelheim), ropinirole (Requip, GlaxoSmithKline), and tolcapone (Tasmar, Valeant) are "probably effective" in reducing off time based on studies reviewed. Due to tolcapone's potential to cause hepatotoxicity and the valvular fibrosis that can occur with pergolide, both agents should be used with caution, and monitoring is required. In a third category, subcutaneous apomorphine (Apokyn, Vernalis), cabergoline, and selegiline were determined to be "possibly effective," whereas it was stated that bromocriptine and sustained-release carbidopa/levodopa are not effective in reducing off time.

Although most people equate Parkinson's disease with motor symptoms, the incidence of nonmotor symptoms is high. In a survey of 99 patients with PD, 88% of responders said they had at least one nonmotor symptom of PD. According to the guidelines, now that treatment of motor symptoms has improved, it has become clear that the nonmotor features of PD, such as dementia, depression, and psychosis, may result in significant disability. The current thinking is that these symptoms may be related to the pathology of PD itself, rather than to general psychiatric conditions. As such, treatments differ.

The Evaluation and Treatment of Depression, Psychosis, and Dementia in Parkinson Disease parameter suggests treating depression with amitriptyline while paying close attention to its anticholinergic side effects. "Amitriptyline has the best studies, but that doesn't mean that other antidepressants would not be better," said Mary L. Wagner, M.S., Pharm.D., associate professor of clinical pharmacy at Rutgers University's Ernest Mario School of Pharmacy. The recommendations are based on evidence in the literature; however, she explained, the QSS points out in some places that treatment supported by the literature may not be the treatment of choice in every situation. According to the guidelines, there is currently insufficient evidence to make recommendations regarding other treatments for depression.

Rivastigmine (Exelon, Novartis) is "probably effective" in improving cognitive function when treating dementia, state the guidelines. However, the degree of benefit is modest, and tremor may worsen. Donepezil (Aricept, Eisai) is also considered "probably effective."