369 Insomnia with objective short sleep duration is associated with increased cortisol in patients with Mild Cognitive Impairment

Abstract

\n \n \n Mild cognitive impairment (MCI) is frequent in the elderly and is in a continuum with dementia in a significant amount of people. Both insomnia and increased cortisol levels have been suggested as risk factors for MCI. The goal of this study was to examine whether activation of the hypothalamic-pituitary-adrenal (HPA) axis, as measured by plasma cortisol levels, is associated with the insomnia with short sleep duration (ISS) phenotype, as measured by actigraphy, in elderly with MCI.\n \n \n \n A sub-sample of 109 subjects with MCI and 92 cognitively non-impaired controls 60 years or older (75.37±6.54y) was recruited from a population-based cohort residing on Crete, Greece. Subjects underwent medical history, physical examination, neuropsychiatric evaluation, neuropsychological testing, 3-day 24-h actigraphy, assessment of subjective insomnia symptoms (i.e., difficulties initiating and/or maintaining sleep), and a morning blood draw to assay for plasma cortisol levels. The ISS phenotype was defined by the presence of at least one insomnia symptom and an actigraphy-measured sleep efficiency below the median of the entire sample (i.e., ≤81%). Group differences in plasma cortisol levels between MCI subjects with and without the ISS phenotype were tested using ANCOVA adjusting for age, gender, BMI and depression.\n \n \n \n Subjects with MCI had higher cortisol levels compared to controls (105.34±9.34 vs. 70.3±10.02 nmol/L, p<0.05). Subjects with MCI and the ISS phenotype (138.38±16.57 nmol/L) had significantly higher cortisol levels compared to those without insomnia (97.74±19.68 nmol/L) or those with insomnia and normal sleep duration (INS; 79.97±16.02 nmol/L, p=0.044). The association between the ISS phenotype and cortisol levels was modified by amnestic symptoms (p-interaction=0.079); commensurate, the ISS phenotype was associated with higher cortisol levels among the amnestic MCI subgroup (INS: 79.12±21.93 vs. ISS: 155.55±20.40 nmol/L, p=0.040), but not among the non-amnestic MCI subgroup (INS: 64.06±23.62 vs. ISS: 89.33±29.00 nmol/L, p=0.559).\n \n \n \n The ISS phenotype is associated with increased cortisol levels in elderly with MCI, particularly those with amnestic type. Improving sleep quality, decreasing cortisol levels and lengthening sleep duration may slow down the progression of these individuals into dementia.\n \n \n \n National Strategic Reference Framework(NSRF), Program: THALES entitled “UOC-Multidisciplinary network for the study of Alzheimer’s Disease” Grant Cod:MIS 377299\n