Depression

Depressive Symptoms Might Be a Very Early Sign of Parkinson’s Disease

Current use of antidepressants was associated with an 80% increased risk of developing Parkinson's disease.
Marlene Busko
Medscape Medical News 2007

May 1, 2007 — Use of antidepressants within the previous year was linked with a higher risk of developing Parkinson’s disease in a large, case-control study.

The study, with lead author Miguel A. Hernan, MD, at Harvard Medical School, in Boston, Massachusetts, was presented at the 59th Annual Meeting of the American Academy of Neurology by coauthor Alvaro Alonso, MD.

Dr. Alonso told Medscape in a phone interview that, based on their findings, the group concluded: “Maybe people who are going to develop Parkinson’s disease start having depressive symptoms, and then later in their course of their disease, they start developing the typical motor symptoms of Parkinson’s, such as tremor or movement.” He added that since Parkinson’s disease followed closely after depressive symptoms, this suggests that depression could be an early part of Parkinson’s disease.

He explained that several previous papers reported that individuals with Parkinson’s disease had a higher risk of developing depression and that patients with Parkinson’s disease had a higher risk of having had prior depression. Previous studies were limited by the small number of cases of Parkinson’s disease and by a lack of information on the timing of the association between depression and Parkinson’s disease. It was not clear whether depression could be an early symptom of Parkinson’s disease, whether depression causes changes in the central nervous system that could increase the risk of developing Parkinson’s disease, or whether there are common factors for both depression and Parkinson’s disease.

The group analyzed data from a large, population-based cohort, the General Practice Research Database, with information on clinical diagnosis, medication use, and lifestyle factors from almost 3 million patients seen by their general practitioners in the United Kingdom. “The good thing about this large data set is that we have access to a lot of cases of Parkinson’s disease, so that gives statistical power to assess our hypothesis,” Dr. Alonso said.

Using this database, they identified 1052 cases of Parkinson’s disease and matched them by age and sex with 6634 control patients. Prescription of an antidepressant was used as a marker for depressive symptoms. The study subjects were divided into current users, past users, or never users of antidepressant medications.

Current use of antidepressants was associated with an 80% increased risk of developing Parkinson’s disease.

Risk of Developing Parkinson’s Disease, Antidepressant Users vs Never Users
Antidepressant User
Odds Ratio (95% CI)
P
Current (within the past year)
1.8 (1.4 – 2.3)
< .0001
Past
1.1 (0.8 – 1.4)
.8

The risk was similar for both men and women, for different age groups, and for use of different classes of antidepressants such as selective serotonin reuptake inhibitors and tricyclic antidepressants. Further analysis revealed that past users of antidepressants had an increased risk of developing Parkinson’s disease in the first year after they stopped taking antidepressants, but the risk was not increased after this.

“Our interpretation of this data is not that antidepressants increase the risk for Parkinson’s disease,” said Dr. Alonso, noting that the risk of developing Parkinson’s disease was the same with different classes of antidepressants that had different mechanisms of action.

He added that since increased risk of developing Parkinson’s disease was apparent only in the year prior to onset of the disease, this supports the hypothesis that depressive symptoms might be an early part of Parkinson’s disease, rather than the hypothesis that depression increases the risk of developing Parkinson’s disease.

American Academy of Neurology 59th Annual Meeting: Abstract P01.120. April 28 – May 5, 2007.

© 2007 Medscape

Source: Medscape.com

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