title: Cortisol awakening response and hippocampal volume: vulnerability for major depressive disorder?
abstract: BACKGROUND
  Major depressive disorder is associated with dysregulated basal cortisol levels and small hippocampal (HC) volume. However, it is still debated whether these phenomena are a consequence of the illness or whether they may represent a vulnerability marker existing before the illness onset. Here, we aimed to examine this notion of vulnerability by assessing whether abnormalities in basal cortisol secretion and HC volumes are already present in a sample of healthy young adults who showed varying levels of depressive tendencies, but at subclinical levels.
  
  
  METHODS
  We recruited healthy young men and women from the local university. On the basis of depression scores derived from standard questionnaires, three groups were formed: a control group (n = 27), a subclinical group (n = 23), and a high-risk subclinical group (n = 9). The participants underwent a magnetic resonance imaging scan and collected saliva samples for the assessment of diurnal cortisol levels.
  
  
  RESULTS
  Both the subclinical and the high-risk subclinical group failed to show a significant increase in cortisol levels after awakening. The high-risk subclinical group also showed a lower area-under-the-curve increase of cortisol levels after awakening compared with control subjects. In addition, this group also had smaller total HC volume compared with control subjects.
  
  
  CONCLUSIONS
  The findings from this subclinical sample suggest that dysregulated cortisol awakening response and small HC volume may constitute vulnerability factors for major depressive disorder. Further investigations are needed to discern the mechanisms that may underlie these phenomena.
authors.affiliation: Douglas Mental Health University Institute, McGill University, Montreal, Canada. katarina.dedovic@mail.mcgill.ca
authors.forename: Katarina
authors.initials: K
authors.lastname: Dedovic
authors.forename: Veronika
authors.initials: V
authors.lastname: Engert
authors.forename: Annie
authors.initials: A
authors.lastname: Duchesne
authors.forename: Sonja Damika
authors.initials: SD
authors.lastname: Lue
authors.forename: Julie
authors.initials: J
authors.lastname: Andrews
authors.forename: Simona I
authors.initials: SI
authors.lastname: Efanov
authors.forename: Thomas
authors.initials: T
authors.lastname: Beaudry
authors.forename: Jens C
authors.initials: JC
authors.lastname: Pruessner
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D003865:Major Depressive Disorder / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size; D010912:Pituitary-Adrenal Function Tests / Q000379:methods; D012307:Risk Factors; D014851:Wakefulness
chemical_list: D015415:Biomarkers; D006854:Hydrocortisone