title: Hippocampal volume in older adults at risk of cognitive decline: the role of sleep, vascular risk, and depression.
abstract: OBJECTIVE
  Decreased hippocampal volume in older adults is associated with neurodegenerative and psychiatric diseases. Several modifiable risk factors have been associated with the size of this structure, however the relative contribution of these factors to hippocampal atrophy is unclear. This study aimed to examine the relationship between modifiable risk factors and hippocampal volume in older adults at risk of cognitive decline.
  
  
  METHODS
  Two hundred and eighteen participants (mean age = 67.3 years, MMSE = 28.6) with mood and/or memory complaints underwent clinical and neuropsychological assessment, and magnetic resonance imaging. Measures of depression, global cognitive functioning, exercise, vascular health, cognitive reserve, sleep, and memory were collected. Hippocampal volumes were derived using image segmentation as implemented by FMRIB Software Library.
  
  
  RESULTS
  Smaller hippocampal volumes were strongly associated with poorer verbal learning and memory as well as diagnoses of either multiple or amnestic mild cognitive impairment. Based on univariate correlations, multivariable regressions were performed (controlling for age and total intracranial volume) to determine which modifiable risk factors were associated with hippocampal volume. For the left hippocampus, poor sleep efficiency and greater than five years untreated depressive illness remained significant predictors. For the right hippocampus, diabetes and low diastolic blood pressure significant predictors.
  
  
  CONCLUSIONS
  Although their contribution is small, lower sleep efficiency, low blood pressure, diabetes, and untreated depression are associated with reduced hippocampal volumes. Studies exploring the impact of early intervention for these risk factors on hippocampal integrity are warranted.
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Elcombe
authors.affiliation: Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, NSW, Australia.
authors.forename: Jim
authors.initials: J
authors.lastname: Lagopoulos
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia.
authors.forename: Shantel L
authors.initials: SL
authors.lastname: Duffy
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, NSW, Australia.
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, NSW, Australia.
authors.forename: Louisa
authors.initials: L
authors.lastname: Norrie
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, NSW, Australia.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
authors.affiliation: Healthy Brain Ageing Program, University of Sydney, NSW, Australia Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, NSW, Australia.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Naismith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis*; D003863:Depression / Q000523:psychology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D012307:Risk Factors; D057566:Self Report; D012890:Sleep
keywords: Dementia; depression; diabetes; hippocampus; hypertension; magnetic resonance imaging; mild cognitive impairment; sleep