title: A review of candidate pathways underlying the association between asthma and major depressive disorder.
abstract: OBJECTIVE
  To consider the mechanisms that may link asthma and major depressive disorder (MDD). Asthma and MDD co-occur at higher rates than expected, but whether this reflects shared underlying pathophysiological mechanisms is not known.
  
  
  METHODS
  A review of the epidemiological data linking asthma and MDD was conducted and the possible biological mechanisms that could account for the high rate of this comorbidity were reviewed.
  
  
  RESULTS
  MDD occurs in almost half of patients with asthma assessed in tertiary care centers. Dysregulation of the hypothalamic pituitary adrenal axis may predispose people to both MDD and asthma, and similar alterations in the immune, autonomic nervous, and other key systems are apparent and may contribute to this increased risk of co-occurrence.
  
  
  CONCLUSIONS
  High rates of MDD in asthma may result from the stress of chronic illness, the medications used to treat it, or a combination of the two. The high level of co-occurrence may also reflect dysregulation of certain stress-sensitive biological processes that contribute to the pathophysiology of both conditions.
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University and Brain-Body Institute, St. Joseph's Healthcare Hamilton, Ontario, Canada.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Van Lieshout
authors.forename: John
authors.initials: J
authors.lastname: Bienenstock
authors.forename: Glenda M
authors.initials: GM
authors.lastname: MacQueen
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology; D001341:Autonomic Nervous System / Q000503:physiopathology; D002648:Child; D015897:Comorbidity; D000242:Cyclic AMP / Q000502:physiology; D051546:Cyclooxygenase 2 / Q000502:physiology; D016207:Cytokines / Q000502:physiology; D003865:Major Depressive Disorder / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D004777:Environment; D005260:Female; D005938:Glucocorticoids / Q000502:physiology; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D008297:Male; D008954:Models, Biological; D016328:NF-kappa B / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D009765:Obesity / Q000453:epidemiology; D018384:Oxidative Stress; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011453:Prostaglandins / Q000502:physiology; D013315:Stress, Psychological / Q000503:physiopathology
chemical_list: D016207:Cytokines; D005938:Glucocorticoids; D016328:NF-kappa B; D018377:Neurotransmitter Agents; D011453:Prostaglandins; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human