Occurrence of depression and anxiety prior to Parkinson's disease

To assess the relationship between depression and anxiety and Parkinson's disease (PD).

Many people with PD suffer from depression and anxiety prior to the onset of motor symptoms. Studies suggest these psychiatric conditions may be risk factors for PD or prodromal non-motor symptoms.

Using a population-based approach in three California counties, we recruited 371 incident PD cases, 402 population and 115 sibling controls. We recorded self-reports of lifetime depression/anxiety diagnoses and use of psychotropic medications. We adjusted for age, race, sex, pack-years of smoking, and education, and also conducted analyses after excluding (lagging) both diagnoses and medication use first occurring within 2, 5, 10, and 20 years of the index/diagnosis date.

Cases were more likely to have received a diagnosis of depression or anxiety at any time prior to index date (OR 1.42, 95% CI 1.01, 2.00), but were not more likely to have been both diagnosed and treated (OR 1.11, 95% CI 0.77, 1.60). Male PD patients received diagnoses combined with treatment more often than population controls within 5 years of PD diagnosis (OR 2.21, 95% CI 1.21, 4.04; 2 year lag: OR 2.44, 95% CI 1.29, 4.61; 5 year lag: OR 1.67, 95% CI 0.80, 3.49). We did not see any differences for females. Results for cases compared to sibling controls were similar to those for population controls.

These results suggest that depression and anxiety may be early symptoms during the prodromal phase of PD.