Depression may be an early symptom of Parkinson's disease, according to research that will be presented at the American Academy of Neurology's 59th Annual Meeting in Boston, April 28 – May 5, 2007.

The study looked at whether people who are taking antidepressant medications are more likely to develop Parkinson's disease than people who are not taking the medications. It found that, in the year before their Parkinson's disease was diagnosed, people who were taking antidepressants were nearly twice as likely to develop Parkinson's disease as those who were not taking antidepressants.

"This should not be interpreted as evidence that antidepressants cause Parkinson's disease," said Miguel Hernan, MD, DrPH, of Harvard School of Public Health in Boston. "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."

For the study, researchers examined a database of more than three million people in the United Kingdom and identified 1,052 people with Parkinson's disease and matched them with 6,634 people without the disease. Then they looked at antidepressant use before the onset of Parkinson's disease.

The increased risk of developing Parkinson's in the year before diagnosis was true for both men and women, across age groups, and for those who used both types of antidepressants, tricyclic antidepressants and SSRIs, or selective serotonin reuptake inhibitors.

Source: American Academy of Neurology.