PT  - JOURNAL ARTICLE
AU  - Helena Gustafsson
AU  - Anna Nordström
AU  - Peter Nordström
TI  - Depression and subsequent risk of Parkinson disease
AID  - 10.1212/WNL.0000000000001684
DP  - 2015 Jun 16
TA  - Neurology
PG  - 2422--2429
VI  - 84
IP  - 24
4099  - http://n.neurology.org/content/84/24/2422.short
4100  - http://n.neurology.org/content/84/24/2422.full
SO  - Neurology2015 Jun 16; 84
AB  - Objective: To investigate the long-term risk of Parkinson disease (PD) after depression and evaluate potential confounding by shared susceptibility to the 2 diagnoses.Methods: The nationwide study cohort included 140,688 cases of depression, matched 1:3 using a nested case-control design to evaluate temporal aspects of study parameters (total, n = 562,631). Potential familial coaggregation of the 2 diagnoses was investigated in a subcohort of 540,811 sibling pairs. Associations were investigated using multivariable adjusted statistical models.Results: During a median follow-up period of 6.8 (range, 0–26.0) years, 3,260 individuals in the cohort were diagnosed with PD. The multivariable adjusted odds ratio (OR) for PD was 3.2 (95% confidence interval [CI], 2.5–4.1) within the first year of depression, decreasing to 1.5 (95% CI, 1.1–2.0) after 15 to 25 years. Among participants with depression, recurrent hospitalization was an independent risk factor for PD (OR, 1.4; 95% CI, 1.1–1.9 for ≥5 vs 1 hospitalization). In family analyses, siblings' depression was not significantly associated with PD risk in index persons (OR, 1.1; 95% CI, 0.9–1.4).Conclusions: The time-dependent effect, dose-response pattern for recurrent depression, and lack of evidence for coaggregation among siblings all indicate a direct association between depression and subsequent PD. Given that the association was significant for a follow-up period of more than 2 decades, depression may be a very early prodromal symptom of PD, or a causal risk factor.CI=confidence interval; ICD=International Classification of Diseases; NCC=nested case-control; NPR=National Patient Register; OR=odds ratio; PD=Parkinson disease