Patients using this anti-anxiety medication and able to tolerate it well should continue its use, but a large-scale study is not advised, its researchers said.
Findings from the trial, which was funded by the Michael J. Fox Foundation, were reported in “A trial of buspirone for anxiety in Parkinson’s disease: Safety and tolerability,” published in the journal Parkinsonism & Related Disorders.
Roughly 30% of Parkinson’s patients experience anxiety disorders, and more than 50% of these people — excluding those with depression — are not given anti-anxiety medications.
No clinical trials are known to have evaluated how these medications might affect Parkinson’s or interact with many of its treatments, the study noted.
Anti-anxiety medications may act differently in people with Parkinson’s due to the effect the disease has on brain chemicals such as serotonin and dopamine, which are involved in responses to anxiety. Some anti-depressants targeting these molecules were studied, but did not prove to be effective in these patients.
Investigators with the University of Rochester reported the findings of a small Phase 2 trial (NCT02803749) that aimed to assess the tolerability of buspirone, an anti-anxiety medication sold under the brand name Buspar, among others, and known to effectively treat generalized anxiety disorder.
The study enrolled 21 adult Parkinson’s patients with significant anxiety, who were randomly assigned to either a placebo (four people) or buspirone (17 people) for 12 weeks. All patients started with 7.5 mg of buspirone or a matching placebo twice daily. The medication’s dose was increased up to a maximum of 30 mg twice daily.
Its main goal was to see how many people stopped treatment before the study’s end due to tolerance issues. Other measures included assessing undesirable side effects, dose reductions, changes in motor function, involuntary muscle movements (dyskinesia), and anxiety.
Seven people on buspirone (41%) dropped out of the study early. Of these, five failed to complete the study because they were unable to tolerate the medication. Another left for a protocol violation, and the seventh because the study was too burdensome.
Of the 17 patients treated with buspirone, 14 (82%) experienced at least one side effect. The most common (reported by at least two patients), which nearly all (90%) rated as mild or moderate, included freezing of gait, tremor, sleep difficulties, dizziness, impaired balance, and fatigue. Nine patients (53%) taking buspirone also saw their motor symptoms worsen during the study.
On average, anxiety lessened among the 10 patients taking buspirone who completed the trial, as measured both from the doctor’s perspective using the Hamilton Anxiety Rating Scale, and from the patient’s point of view, via the Parkinson Anxiety Scale. Hamilton scale scores decreased by an average of 3.9 points, and Parkinson’s Scale scores by an average of 7.1.
Although investigators concluded that “tolerability concerns do not support moving forward with a large-scale efficacy trial,” they also pointed out that, based on their results, patients with Parkinson’s should not stop taking buspirone if they currently tolerate it well.
While large-scale trials are not advised, the fact that the medication did relieve anxiety among patients who tolerated it indicated that additional studies are warranted, the researchers suggested.
“Future studies should examine predictors of intolerability or response to buspirone, assess buspirone monotherapy, and focus on alternative anxiety treatments for those with PD [Parkinson’s disease],” they wrote.
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