title: The impact of subcortical white matter disease on mood in euthymic older adults: a diffusion tensor imaging study.
abstract: OBJECTIVE
  Clinical depression in the elderly is associated with cerebral small vessel disease. It is less certain whether the endorsement of depressive symptoms in the absence of clinical depression, relatively common in euthymic older adults, is also associated with white matter damage. The majority of studies exploring this issue have produced mixed results, perhaps due, in part, to differences in defining the threshold for depression, notating vascular risk factors, and/or the neuroimaging tools used to quantify white matter damage. We aimed to address these issues with non-demented euthymic older adults.
  
  
  METHODS
  We performed diffusion tensor imaging (DTI) and T2-weighted magnetic resonance imaging (MRI) in a population based cohort of 79 individuals (mean age = 68 years).
  
  
  METHODS
  In addition to neuroimaging, the authors report assessments of overall cognition, executive functioning, and depression.
  
  
  RESULTS
  Scores on the Geriatric Depression Scale 15-item (GDS-15) correlated with DTI measures of mean diffusivity (r [77] = 0.23, p = 0.039) and fractional anisotropy (r [77] = -0.22, p = 0.045) but only approached significance for T2-weighted MRI measures of white matter hyperintensities (WMH; r [77] = 0.21, p = 0.053). After adjusting for factors known to influence the development of WMH and depression, including age and vascular risks, DTI-derived indices of white matter integrity remained significantly associated with GDS-15 scores. Furthermore, only DTI-derived measures of white matter integrity contributed to the variance in GDS-15 scores in logistical regression modeling.
  
  
  CONCLUSIONS
  These findings demonstrate an association between white matter damage and the endorsement of depressive symptoms in euthymic older adults and suggest that DTI may be more sensitive to this damage than T2-WMH in an aging cohort with multiple vascular risk factors.
authors.affiliation: Department of Psychology, Institute of Psychiatry, King's College, London, UK. m.lamar@iop.kcl.ac.uk
authors.forename: Melissa
authors.initials: M
authors.lastname: Lamar
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Charlton
authors.forename: Robin G
authors.initials: RG
authors.lastname: Morris
authors.forename: Hugh S
authors.initials: HS
authors.lastname: Markus
mesh_terms: D000339:Affect; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology / Q000523:psychology; D016880:Anisotropy; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D015331:Cohort Studies; D003866:Depressive Disorder / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D056324:Diffusion Tensor Imaging; D056344:Executive Function; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012307:Risk Factors; D012647:Self-Assessment; D011795:Surveys and Questionnaires