title: The bidirectional longitudinal relationship between insomnia, depression and anxiety in patients with early-stage, medication-naïve Parkinson's disease.
abstract: While anxiety, depression and insomnia frequently (co-)occur in Parkinson's disease (PD) patients, little is known about their temporal relationship. In this study, we tested two hypotheses: i) insomnia predicts an increase in symptoms of depression or anxiety and ii) anxiety or depression at baseline predicts insomnia in PD patients six months later.
  
  
  
  We used longitudinal data from a prospective cohort study of early-stage, medication-naïve PD patients. Primary outcome measures were: anxiety symptoms, measured with the State-Trait Anxiety Inventory (STAI); depressive symptoms, measured with the 15-item Geriatric Depression Scale (GDS-15); and insomnia, defined as a score ≥ 2 on item 1.7 of the Movement Disorder Society - Unified Parkinson's Disease Rating Scale. We performed linear and logistic regression analyses, correcting for baseline value of the respective outcome variable.
  
  
  
  Baseline insomnia was not associated with GDS-15 or STAI total score at follow-up. In a post hoc analysis, we found that insomnia predicted a higher STAI State score (B(SE) = 2.50 (1.07), p < 0.05), while the association with the STAI Trait score was not significant. Baseline STAI scores (B(SE) = 0.02 (0.01), p = 0.001) and GDS-15 score (B(SE) = 0.15 (0.05), p < 0.001) were significantly associated with insomnia at follow-up.
  
  
  
  Symptoms of anxiety and depression may constitute a risk factor for insomnia in PD. The relationship between insomnia and anxiety is bidirectional, which suggests that both anxiety and sleep disorders can start a negative spiral in PD patients, where one enhances the other. Independent clinical attention for these symptoms in PD patients is therefore warranted.
authors.affiliation: Department of Psychiatry, VU University Medical Center (VUmc), The Netherlands; Department of Anatomy & Neurosciences, VUmc, The Netherlands. Electronic address: s.rutten@vumc.nl.
authors.forename: Sonja
authors.initials: S
authors.lastname: Rutten
authors.affiliation: Department of Psychiatry, VU University Medical Center (VUmc), The Netherlands; Department of Anatomy & Neurosciences, VUmc, The Netherlands; Amsterdam Neuroscience, Amsterdam, The Netherlands; Department of Neurology, VUmc, The Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: Vriend
authors.affiliation: Department of Anatomy & Neurosciences, VUmc, The Netherlands; Amsterdam Neuroscience, Amsterdam, The Netherlands.
authors.forename: Ysbrand D
authors.initials: YD
authors.lastname: van der Werf
authors.affiliation: Amsterdam Neuroscience, Amsterdam, The Netherlands; Department of Neurology, VUmc, The Netherlands.
authors.forename: Henk W
authors.initials: HW
authors.lastname: Berendse
authors.affiliation: Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Weintraub
authors.affiliation: Department of Psychiatry, VU University Medical Center (VUmc), The Netherlands; Department of Anatomy & Neurosciences, VUmc, The Netherlands; Amsterdam Neuroscience, Amsterdam, The Netherlands.
authors.forename: Odile A
authors.initials: OA
authors.lastname: van den Heuvel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001007:Anxiety / Q000150:complications* / Q000175:diagnosis; D015331:Cohort Studies; D003863:Depression / Q000150:complications* / Q000175:diagnosis; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000175:diagnosis; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications*
keywords: Anxiety; Depression; Insomnia; Longitudinal; Parkinson's disease; Risk factor