Alzheimer Hastalığında Otonom Fonksiyonun Kalp Hızı Türbülansı ve Kalp Hızı Değişkenliği ile Değerlendirilmesi

Abstract

Alzheimer’s disease (AD) is the most common neurodegenerative disorder of the central nervous system characterized by progressive short-term memory loss, intellectual and emotional dysfunction, and alternations in autonomic and neuroendocrine functions. It has been suggested that the autonomic nervous system may be impaired in AD associated with cholinergic deficits, as acetylcholine is essential for parasympathetic and pre-ganglionic sympathetic neurotransmission. Therefore, increased risk of dysrhythmia and falls is observed in AD patients indicating cardiovascular autonomic dysfunction. Heart rate variability (HRV), heart rate turbulence (HRT) and QT dynamics are non-invasive methods for the assessment of autonomic function which requires less cooperation and is suitable to use in patients with dementia. HRT is a parameter that demonstrates baroreflex sensitivity and it has not been studied in AD patients before. The aim of this study was to demonstrate cardiovascular autonomic dysfunction in AD patients by using HRV, HRT and QT dynamics. Thirty-three AD patients and 31 subjects with normal cognitive function aged 65 years and over admitted to the outpatient clinic of the Division of Geriatric Medicine, Department of Internal Medicine, at Hacettepe University Hospital were enrolled in this study. AD patients met NINCDS-ADRDA criteria. Autonomic function was assessed by HRV, HRT and QT dynamics. In univariete analysis, HRT parameters were significantly different between the groups; turbulence onset (TO) was significantly higher (-0.69, (-3.63-3) vs -1.97, (-3.62-2.63), p=0.001) and turbulence slope (TS) was significantly lower (5.20, (0.50-15.20) vs 10.10, (1.50-16.70), p=0.023) in AD patients than subjects with normal normal cognitive function. In multiple linear regression model presence of AD was found to be an independent predictor for TO and TS; (β:0.979, %95CI: 0.120 - 1.838, p=0.026) and (β:-3.931, %95 CI: -6.333--1.529, p=0.002), respectively. There was no significant difference between AD patients and normal cognitive function subjects regarding HRV and QT dynamics. This is the first study showing autonomic dysfunction in AD patients via HRT parameters. Autonomic dysfunction may accompany AD and may cause a decrease in quality of life. Also, autonomic dysfunction may play role in the development of AD. Therefore, further prospective studies is required for the elucidation of the complex relationship between autonomic dysfunction and AD.