The Movement Disorders Society held its annual convention in Sydney, Australia recently. Many interesting topics dealing with Parkinson’s disease were discussed. Some of those topics will be addressed here.
A report on mild cognitive impairment in Parkinson’s by Alison Yarnell, from Newcastle University in the United Kingdom, showed that if cognitive impairment was present at the time of Parkinson’s diagnosis, the patient had a higher risk for developing dementia later in the disease progression. A clinical trial compared neurological and cognitive assessments of 219 newly diagnosed subjects with Parkinson’ s to 99 age-matched controls. Cognitive assessments covered global cognition, attention, memory, executive function, visuospatial function and language. Subjects were classified dependent on their scores. Memory impairment was the most common, with 15 percent of the subjects affected followed by visuospatial deficit s in 13 percent, attention in 12 percent and executive function at 11 percent. Other studies have shown cognitive impairment in as many as 25 percent of the Parkinson’s population with many going on to develop dementia within three years of diagnosis The author of this study stressed that cognitive testing should be done at the time of diagnosis to both get a baseline and also to determine which patients might be in need of closer monitoring. By determining cognitive status early on in the course of the disease, therapeutic interventions may provide better results.
Clinical trial design was another interesting topic at the MDS meeting. Dr. Tiago Mestre from Toronto Western General Hospital in Ontario, Canada, raised the question of how participants’ attitudes and reactions to placebos in double blind trials influenced the evaluations of the effectiveness of the therapeutic agent being evaluated. To try to understand if this is indeed a real effect, a systematic review of double-blind, randomized, controlled trials of dopamine agonists in Parkinson’s that used a placebo or an active control. The analysis of their preliminary results did show a clinically significant impact of decreased effectiveness of the medication being tested. Therapeutic effectiveness might be even higher for the drug being tested than trial results indicate. This negative effect of a placebo in a trial is called the “Lessebo” effect.
One commenter also raised the question of the “nocebo” effect…where if a patient is given a placebo, or non-therapeutic substance, by an authority figure who assures them of the benefit, a benefit will be experienced. Another patient who is more skeptical and less trusting might experience a harmful effect, when, indeed, the “active” ingredient is not known to cause harm.
Dr. Rajesh Pahwah , from the University of Kansas Medical center presented research on a new formulation of an older medication has shown promise in controlling levodopa induced dyskinesias in Parkinson’s. There are currently no approved medications to treat levodopa induced dyskinesias. It is still in the investigational stages, but a timed-release form of amantidine has been successful in a small clinical trial. Amantidine has been around for a long time, and has been used to reduce dyskinesias but doses hight enough to be effective have often not been well tolerated. .The new formulation is designed to gradually increase the availability of the drug in the day time, when the dyskinesias are the most disturbing, and to limit the overnight concentration thereby helping to relieve insomnia and sleep disturbances. Because higher doses can be administered gradually in timed-release, effectiveness and tolerability are both improved. The new formulation, called a “chronotherapeutic” pharmacokinetic profile, is not yet FDA approved and not out of the clinical trial testing stages. Some mild adverse events have been reported, but the company is seeking the advice of the FDA on continuing development of this medication.