NEW YORK (Reuters Health) – The dopamine agonist pramipexole relieves depressive symptoms in patients with Parkinson’s disease, according to a study published online May 10th in The Lancet Neurology.

More than a third of patients with Parkinson’s disease have clinically significant depression, and the reported mean prevalence of major depression in these patients is 17%, according to lead author Dr. Paolo Barone, of the University of Naples Federico II in Italy, and colleagues.

The researchers recruited 296 patients with mild to moderate Parkinson’s disease and baseline scores of at least 5 on the geriatric depression scale (range, 0 to 15) and randomized them to receive either pramipexole for 12 weeks, or placebo.

Patients were allowed to continue on antidepressant drugs if they’d been on a stable dose for at least 6 weeks. They could also continue on stable doses of levodopa formulations, amantadine, anticholinergic drugs, and certain other medications.

At 12 weeks of treatment, patients on pramipexole were receiving a mean daily dose of 2.18 mg, and the placebo group was taking a mean dose equivalent to 2.51 mg.

Mean scores on the Beck Depression Inventory decreased from 18.7 to 13.1 after 12 weeks in the pramipexole groups and from 19.2 to 15.0 in the placebo group. The adjusted mean change was -5.9 in the treatment group and -4.0 in the placebo group (p = 0.01). There was also a significant improvement with pramipexole over placebo on the geriatric depression score.

The difference with pramipexole remained significant when patients taking antidepressants were excluded,

The researchers also tested motor function using the unified Parkinson’s disease rating scale. The motor score improved by 4.4 points in the pramipexole group and 2.2 points in the placebo group (p = 0.003).

Adverse event rates were similar between the two groups, and the investigators wrote that the pramipexole-related events were “generally consistent with the known safety profile” of the drug.

“These results suggest that specific stimulation of dopaminergic pathways as provided by pramipexole should be considered in the management of patients with Parkinson’s disease and clinically significant depressive symptoms,” the researchers wrote. “This strategy might offer a combined, although independent, benefit on motor disability, depressive symptoms, and quality of life.”

In an editorial, Dr. Hubert H. Fernandez of the University of Florida in Gainesville and Dr. Marcelo Merello of Fundacio para la Lucha contra las Enfermedades Neurologicas de la Infancia in Buenos Aires note “there is little doubt that (depression) is an integral part” of Parkinson’s disease.

They point out that the patients in this study were not diagnosed with depression using strict DSM-IV criteria. “Nevertheless, this particular design is likely to provide a good representation of clinical practice, in which patients with Parkinson’s disease are commonly given antidepressant drugs on the basis of reports of depressive symptoms,” they add.

While more studies are needed to confirm that pramipexole would be safe and appropriate for patients with severe depression or advanced Parkinson’s disease, “for now…evidence of a positive effect of one drug on both motor and non-motor domains is an important addition to the treatment armamentarium against Parkinson’s disease,” Dr. Fernandez and Dr. Merello conclude.

Reference:

Lancet Neurology 2010.