title: Cortisol levels in fingernails, neurocognitive performance and clinical variables in euthymic bipolar I disorder.
abstract: Neurocognitive impairment has been found in bipolar patients. Hypercortisolemia is one possible cause but there has been no agreement on this. Previous sampling methods assessed only acute cortisol levels, whereas the association between cortisol and psychopathology might be better understood by investigating chronic levels. Fingernails are a novel method for measuring chronic cortisol concentration (CCC). Here, we measured CCC in euthymic bipolar disorder I (BD-I) patients and healthy controls using fingernails to investigate whether differences in CCC influenced neurocognitive performance. We also investigated whether differences in clinical illness variables influenced CCC in euthymic BD-I patients.
  
  
  
  A previous study demonstrated neurocognitive impairment in euthymic BD-I patients. The current study included a portion of this sample: 40 BD-I versus 42 matched controls who provided fingernail samples.
  
  
  
  There was no statistically significant difference in CCC between controls and BD-I (P = .09). Logistic regression analyses revealed that euthymic bipolar I subjects with more than five years of current euthymia had decreased odds of having higher fingernail cortisol concentration (>71.2 pg/mg) compared to those with less than 1.5 years (P = .04). There was no association between CCC and cognitive impairment in all domains before and after adjustment for age and sex.
  
  
  
  The current evidence suggests CCC is not a trait biomarker in euthymic BD-I (BD-I). Longer periods of stability in affective disorders are associated with lower CCC. Fingernail cortisol does not seem to be implicated in neurocognitive impairment and BD-I. Future studies may investigate CCC in different illness phases of BD-I.
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.|b Departamento de Clínicas, Facultad de Medicina , Universidad Católica del Norte , Coquimbo , Chile.
authors.forename: Andres
authors.initials: A
authors.lastname: Herane-Vives
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cleare
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Chin-Kuo
authors.initials: CK
authors.lastname: Chang
authors.affiliation: c Facultad de Medicina , Universidad de Chile , Santiago , Chile.
authors.forename: Valeria
authors.initials: V
authors.lastname: de Angel
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Papadopoulos
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Susanne
authors.initials: S
authors.lastname: Fischer
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Rozmin
authors.initials: R
authors.lastname: Halari
authors.affiliation: d Tuen Mun Mental Health Centre, TMMHC , Hong Kong.
authors.forename: Eric Y W
authors.initials: EYW
authors.lastname: Cheung
authors.affiliation: a Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience , King's College London , London , UK.
authors.forename: Allan H
authors.initials: AH
authors.lastname: Young
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001714:Bipolar Disorder / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D060825:Cognitive Dysfunction / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009262:Nails / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D006854:Hydrocortisone
keywords: Fingernails; bipolar I disorder; cognition; cortisol; euthymia