Dissertação de Mestrado
Correlação entre o nível de cortisol salivar e o desempenho cognitivo em idosos sem déficit cognitivo
Mario Oscar Pimentel Braga de Souza Lima
Introduction: The chronic stress, measured by the hypercortisolism, has been associated with cognitive decline, but cognitive impairment, low education level and the collection time of the salivary cortisol might modify this association. Objectives: To investigate the association between the performance in cognitive tests and salivary cortisol levels among elderly with medium to high education level and no cognitive impairment. Methods: 244 elderly (60+ years-old) from Belo Horizonte, Brazil, were invited, with at least four years of schooling with no cognitive impairment defined by the Mini-Mental cutoff points of 18 for elderly between four and seven years of schooling and 26 points for those with eight or more years. Exclusion criteria were: a) severe sight, hearing or speech dysfunction as it could affect the apprehension and performance of cognitive tests; b) regular use of oral corticosteroids, benzodiazepines, cholinesterase inhibitors or psychotropic drugs. The cognitive tests were: semantic and phonemic verbal fluency, Word List learning, recall and recognition from the Consortium to Establish a Registry for Alzheimers Disease and the Trail Making test B. Participants were trained to collect the salivary cortisol at home, two days before the interview, at 11p.m., using a saliva device (Salivette®). The data collected also included: socio-demographic characteristics, lifestyle habits, medications, comorbidities, mental disorders, insomnia and stressful life events. Results: 196 elderly participated with an average age of 68.9 (SD= 6.4) years, 89.8% women, and 12.2 (SD=4) years of schooling. The number of corrected words in the recall test, in multiple linear regression, increased among women (=1.273, 95%CI=2.121, 4.259) and increasing years of schooling (=0.075, 95%CI=0.151, 3.844) and decreased with increasing cortisol levels (= -0.301, 95%CI= -5.940, -0.008), ageing (=-0.036, 95%CI=-7.644, 0.004), decreasing monthly family income (from =-0.893; 95%CI=-1.529, -0.256 to =-1.272, 95%CI=-2.064, -0.480), use of dual-action antidepressants (=-1.350, 95%CI=-2.491, -0.210) and common mental disorders (=-0,505, 95%CI=-1.036, -0.026). The ability to accomplish the Trail Making test B, evaluated by multivariate logistic regression, was directly associated with higher levels of cortisol (OR= 1.46, 95%CI=1.01, 2.13), increasing years of schooling (OR=1.16, 95%CI=1.07, 1.27) and higher scores of subjective social status in the society (OR= 1.26, 95%CI=1.04, 1.55). It was also inversely associated with ageing (OR=0.94, 95%CI=0.90, 0.99). Discussion: The association found between higher levels of salivary cortisol and the decrease of the memory performance is compatible with the results of the majority prospective elderly studies without cognitive impairment and similar schooling level. In the Trail Making test B, the capacity to accomplish the test was associated with the increase of cortisol, possibly because of the improvement of the elderly attention. Conclusion: Higher cortisol levels increased the capacity to accomplish the TMB test, but decreased the performance on the memory test.