Relationship Between Cortisol Levels and Memory Performance may be Modulated by the Presence or Absence of Cognitive Impairment: Evidence from Healthy Elderly, Mild Cognitive Impairment and Alzheimer's Disease Subjects
Affiliations: [a] Department of Medical-Surgical Nursing, School of Nursing, University of São Paulo, São Paulo, Brazil | [b] Behavioral and Cognitive Neurology Unit, Department of Neurology, Faculty of Medicine, University of São Paulo, São Paulo, Brazil | [c] Center for Studies on Human Stress, Mental Health Research Center Fernand-Seguin, Hospital Louis-H. Lafontaine, Université de Montreal, Canada | [d] Behavioral and Cognitive Neurology Unit, Department of Internal Medicine, Faculty of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil
Correspondence:
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Correspondence to: Paulo Caramelli, MD, PhD, Departamento de Clínica Médica, Faculdade de Medicina da UFMG, Av. Prof. Alfredo Balena, 190 – 2° andar – sala 246., 30130-100, Belo Horizonte (MG) – Brazil. Tel.: +55 31 3409 9746; Fax: +55 31 34099745; E-mail: caramelp@usp.br.
Abstract: An inverted U-shape function between cortisol levels and memory performance has been reported in studies on both young animals and humans. Yet little is known about this relationship in normal aging or in older subjects with cognitive impairment. This issue is particularly significant since increased levels of cortisol have been reported in Alzheimer's disease (AD). The present study examined the association between cortisol levels and visual memory performance in healthy subjects as well as in individuals presenting mild cognitive impairment (MCI) or AD. Salivary cortisol was measured in 40 healthy elderly subjects, 31 individuals with amnestic MCI, and 40 subjects with mild probable AD. Memory performance was evaluated using the Brief Cognitive Screening Battery. Higher cortisol levels were associated with better memory performance in healthy elderly (p=0.005), while higher cortisol levels were correlated with poorer memory performance in MCI subjects (p=0.011). No correlation between cortisol and memory was found in the AD group (p > 0.05). These results suggest that the relationship between cortisol levels and memory performance in the aging process could vary according to the presence or absence of cognitive impairment.
