Estudo dos efeitos da meditação mindfulness associada a estimulação transcraniana por corrente contínua sobre a variabilidade da frequência cardíaca de idosos

Abstract

Introduction: Aging is a process that generates damage to the autonomic nervoussystem, leading to a decrease in heart rate variability (HRV). Low HRV indices are directly related to poor cardiovascular prognosis. Physical training is an established method capable of improving HRV. However, it is important to rule out that a certain partof the population does not have access to adequate physical training programs, to carry out an exercise protocol prescribed by a qualified professional, to carry out a safe and optimized training. It is plausible to assume that the elderly people are part of this groupof people who have less access to supervised training programs, due to low independence, with limited mobility, in addition to the fact that these programs are scarce and often expensive. Thus, new tools that seek to improve HRV are emerging, such as mindfulnessmeditation (MM). On the other hand, there is also a new technique through transcranial direct current stimulation (tDCS), which has been shown in few studies, in association with physical training, that it can potentiate the benefits of training on HRV. No entanto,no melhor do nosso conhecimento e após busca extensiva na literatura científica, não foiencontrado nenhum estudo que tenha associado as técnicas de MM com a ETCC com o objetivo de induzir melhora nos índices de VFC. Objectives: To evaluate the influence of MM associated with tDCS on the autonomic modulation of heart rate in the elderly, using HRV indices. We also aimed to assess the level of physical activity, quality of life,anxiety, depression and the level of cognitive function of the elderly studied. Finally, weaim to correlate the findings of the assessments with the HRV indices. Methods: Eleven volunteers of both sexes, aged 60 years or older and mean age of 69.1 ± 7.2 years, were selected. All volunteers were submitted to an initial interview, for the composition of the group profile, according to our inclusion and exclusion criteria. Subsequently, they were evaluated through questionnaires, such as quality of life (SF-36), level of physical activity and sedentary lifestyle (IPAQ), cognitive function (Mini Mental State ExaminationMMSE), level of anxiety and depression (HAD). HRV data were collected with the elderly in the supine position, for a period of 75 minutes divided into: 20 minutes at baseline; 15 minutes of meditation; 20 tDCS; and 20 minutes post-stimulus. HRV was collected using a Polar RS810 heart rate monitor and tDCS was applied with the DCStimulator Plus NeuroCon equipment. The elderly received a constant electrical current of 2 mA for 20 minutes to stimulate the anodic polarity on the left CT, where the anode was positioned in the T3 region, located 40% of the distance to the left of the Cz point, according to international standards for EEG 10-20 system. The cathodic electrode was placed over the contralateral supraorbital area (Fp2). Finally, HRV data were extracted and analyzed using the Kubios HRV Standard software, using linear methods in the time and frequency domain and non-linear methods. Results: Significant improvement was observed in most of the HRV indices studied after combined therapy with MM plus tDCS. In the analysis of time domain variables, the SDNN showed a significant increase from baseline (23.8 ± 26.3 ms) to tDCS (31.8 ± 34.5 ms; p = 0.0002) and meditation (27 ± 28, 3 ms) for tDCS (p = 0.01). RMSSD showed a significant increase from baseline (27.2 ± 35.9 ms) to tDCS (36.7 ± 50.7 ms; p = 0.03). All HRV indices analyzed in the frequency domain showed significant improvement. LF showed a significant increase from baseline (369.6 ± 602.4 ms2) to tDCS (672.2 ± 1034.1 ms2; p = 0.0009) and from meditation (352.8 ± 599.1 ms2) to tDCS (p = 0.001). HF showed a significant increase from baseline (207.4 ± 375.5 ms2) to tDCS (896.8 ± 1958.7 ms2 p = 0.001). In the analysis of nonlinear indices, we observed a statically significant increase in the SD1 variable from baseline (19.2 ± 25.4 ms) to tDCS (26 ± 35.9 ms; p = 0.02). And in the variable SD2 showing a significant increase both from baseline (27.4 ± 27.6 ms) for tDCS (36 ± 34 ms; p = 0.0002) and meditation (28.9 ± 27.2 ms) for tDCS (p = 0.008). The quality of life presented scores with scores ranging from 47.3 ± 44 for the physical aspect domain and 72.7 ± 36 for the emotional aspect domain. In the assessment of anxiety and depression, we documented that only one volunteer was classified as probable for the diagnosis of both situations. None of the volunteers practiced vigorous physical activity and all reported performing some physical activity considered as moderate by the IPAQ questionnaire, thus, all were classified as active by the tool used. In the assessment of the level of cognitive function, many volunteers had a maximum score and no volunteer was diagnosed with cognitive decline. Finally, a moderate negative and statistically significant correlation was observed between the time spent sitting by the elderly and some HRV indices, as well as a moderate positive and significant correlation between the time spent walking and HRV indices. Conclusions: The association of meditation using MM and tDCS techniques was able to induce an improvement in cardiac autonomic modulation with an increase in HRV indices. The elderly studied had a regular quality of life, they were active, only one elderly person had anxiety and depression probity and no elderly person had a reduced cognitive level. Those elderly who spent more time sitting had lower HRV indices, on the other hand, the elderly who walked more during the week had higher HRV indices.