Função cognitiva no envelhecimento de indivíduos com deficiência congênita e isolada do hormônio do crescimento

Abstract

Introduction: Dementia syndromes are the leading cause of disability and dependence among the elderly worldwide. The main risk factor for the development of the disease is aging. As growth hormone (GH) secretion declines with age, the administration of GH and of GH releasing hormone (GHRH) agonists has been proposed to alleviate the alarming increase in cognitive disorders of aging, with unclear impacts. Individuals with untreated isolated GH deficiency (IGHD) due to an inactivating mutation in the GHRH receptor (GHRHR) gene, from Itabaianinha, Brazil, have normal life expectancy, and an extended healthspan. We hypothesize that their extended healthspan is accompanied by a delay in the onset of cognitive decline that occurs during the aging process. Objective: To assess the cognitive function in individuals over 50 years with untreated IGHD due to the c.57 + 1A → G mutation in the GHRHR gene. Methods: This is a cross-sectional study with 15 IGHD individuals over 50 years and 15 controls matched by age, sex, years of education, and illiteracy. Laboratory tests were performed to exclude secondary causes of dementia syndromes and the Literacy Independent Cognitive Assessment Test (LICA) was applied. Results: All individuals were negative for HIV and syphilis serology, IGHD subjects had serum levels of folate, vitamin B12 and Thyroid-Stimulating Hormone (TSH) similar to the controls, while free thyroxine (FT4) was higher in the IGHD group. IGHD subjects had a higher total LICA score than controls, 215 (22.7) vs. 204.2 (18.1), without reaching statistical significance. Scores of memory, visuoconstruction, language and calculation were similar between the two groups, with better attention [9.5 (1.4) vs. 8.3 (1.1), p= 0.01], and executive function [38.3 (4.8) vs. 35.1 (2.5), p= 0.03] scores in IGHD. MANCOVA revealed that group (but no age) had a significant effect on the LICA variables (partial eta squared 0.455, power 0.812, p= 0.02). This effect is verified on attention (partial eta squared 0.216, power 0.749, p= 0.01) and executive function (partial eta squared 0.154, power 0.570, p= 0.03. None of the individuals in either the IGHD group or the control group obtained a score compatible with the diagnosis of dementia syndrome. LICA application time was similar in DIGH and control groups. Conclusion: IGHD during the aging process is associated with similar total cognitive performance, but better attention and executive function than controls.