title: Cognitive performance and the course of depressive symptoms over 7 years of follow-up: the SMART-MR study.
abstract: BACKGROUND
  Depressive symptoms and cognitive impairment often co-occur, but their interactive relationship is complex and the direction of causation is still a topic of research. We examined the influence of cognitive performance on the course of depressive symptoms during 7 years of follow-up in patients with vascular disease.
  
  
  METHODS
  Within the SMART-MR study, 736 patients (mean age 62 ± 10 years) had neuropsychological assessment on four cognitive domains at baseline [memory (MEM), working memory (WMEM), executive functioning (EXEC), and information processing speed (SPEED)]. Depressive symptoms were assessed with the Patient Health Questionnaire-9 (PHQ-9) at baseline and every 6 months during 7 years of follow-up. Generalized Estimating Equation (GEE) models were used to assess the association between cognitive performance with depressive symptoms at multiple time points during follow-up. Interaction terms between the respective cognitive domains and time was included to examine if the course of depressive symptoms differed according to baseline cognitive performance.
  
  
  RESULTS
  The GEE analyses showed no significant interactions between the respective cognitive domains and time indicating no different course of depressive symptoms according to baseline cognitive performance. Lower MEM, EXEC or SPEED, but not WMEM performance, was significantly associated with more depressive symptoms during follow-up per z score decrease: MEM [B = 0.70, 95% confidence interval (CI) 0.35-1.05]; EXEC (B = 0.88, 95% CI 0.41-1.36), and SPEED (B = 0.57, 95% CI 0.21-0.92).
  
  
  CONCLUSIONS
  Poorer cognitive performance on the domains MEM, EXEC and SPEED, but not WMEM, was associated with higher levels of depressive symptoms over 7 years of follow-up, but not with a different course of depressive symptoms over time.
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Kooistra
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: N P A
authors.initials: NP
authors.lastname: Zuithoff
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: A M
authors.initials: AM
authors.lastname: Grool
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Zinsmeester
authors.affiliation: Department of Neurology,Brain Center Rudolf Magnus,University Medical Center Utrecht,The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Biessels
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: Y
authors.initials: Y
authors.lastname: van der Graaf
authors.affiliation: Julius Center for Health Sciences and Primary Care,University Medical Center Utrecht,The Netherlands.
authors.forename: M I
authors.initials: MI
authors.lastname: Geerlings
mesh_terms: D001921:Brain / Q000473:pathology; D003072:Cognition Disorders / Q000150:complications* / Q000473:pathology; D015331:Cohort Studies; D003863:Depression / Q000150:complications* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014652:Vascular Diseases / Q000150:complications*
keywords: longitudinal