Parkinson’s May be Prefaced by Depression

Parkinson\’s May be Prefaced by Depression BOSTON, April 30 — Depression, measured by antidepressant use, may be an early symptom of Parkinson’s disease, reported investigators here.

A nearly twofold additional risk of the disease emerged if patients were taking antidepressants in the year before a diagnosis of Parkinson’s, compared with those not taking antidepressants, reported Miguel A. Hernan, M.D., Dr.P.H., of the Harvard School of Public Health, and colleagues.

“Use of antidepressants is associated with the risk of developing Parkinson’s disease, both in men and women, in younger and older individuals,” they wrote in a poster to be presented May 1 at the American Association of Neurology meeting here. “This association is only apparent in the year before the onset of Parkinson’s disease, suggesting that depression can be an early symptom of the disease.”

The investigators emphasized that they were looking at antidepressants as a marker for depression, and not as potential causative agents.

Although several studies have discerned a link between Parkinson’s disease and depression, “the limited sample size in previous reports has precluded subgroup analysis and an accurate timing of this association,” the authors noted.

They conducted a case-control study drawing on information from the General Practice Research Database, which covers more than three million patients in the United Kingdom.

They identified 1,052 cases of Parkinson’s disease, and matched them by age, gender, and general practice with 6,634 controls. Patient use of antidepressants before the onset of Parkinson’s was determined through computerized records. The authors also conducted a medical record review on a sample of computerized Parkinson’s cases, and confirmed the diagnosis in more than 90% of those with two or more prescriptions for anti-parkinsonian drugs (e.g., dopamine agonists).

They found that compared with patients who never used antidepressants, current users of antidepressant had an odds ratio for Parkinson’s disease of 1.8 (95% confidence interval, 1.4 to 2.3, P<0.0001). In contrast, there was no significant difference in Parkinson's disease risk between past (but not current) users of antidepressants and never-users (odds ratio 1.1, 95% CI, 0.8 to 1.4, P=0.08). The risk for Parkinson’s disease was similar whether the antidepressant users took a selective serotonin-reuptake inhibitor or tricyclic antidepressant. Men and women who took antidepressants had equivalent risks for Parkinson’s, and risk did not change across age groups, the authors wrote. “When we assessed the risk of Parkinson’s disease according to time elapsed since last use of anti-depressants, the increased risk was only evident in the first year after stopping taking this treatment, but not later,” the authors wrote. “This should not be interpreted as evidence that antidepressants cause Parkinson’s disease,” said Dr. Hernan. “The relationship is only apparent in the year before the onset of the disease, which suggests that depression is an early symptom of the disease.” Information about the study’s funding source or author conflicts of interest was not available.
Primary source: American Academy of 2007Neurology Annual Meeting
Source reference:
Hernan MA et al. “Antidepressants Use and the Risk of Parkinson’s Disease.” Abstract P01.120, to be presented May 1.
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* Explain to patients who ask that antidepressant use in this study was a marker for depression. The study results do not suggest that antidepressants cause Parkinson’s disease.

* This study was published as an abstract and will be presented at a conference. These data and conclusions should be considered to be preliminary as they have not yet been reviewed and published in a peer-reviewed publication.

By Neil Osterweil, Senior Associate Editor, MedPage Today
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
April 30, 2007

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