Assessment of heart rate variability and occurrence of falls in Alzheimer's disease: an exploratory study.

Aging is accompanied by an increasing incidence of dementia. Alzheimer's disease (AD) is the leading cause of dementia, and it impairs autonomic function. Heart rate variability (HRV) is a marker of autonomic function, but findings in AD are conflicting, and there is scant information on the association of HRV with falls in dementia patients.To assess autonomic activity in older adults with AD, comparing these patients to older adults without dementia (the control group, CG), and to investigate the relationship between HRV and falls.The HRV was analyzed in older adults without dementia and in those with AD using a heart rate monitor. The measurements were made on a single day in the supine and orthostatic positions for 10 minutes each. The HRV components in the time and frequency domains were assessed, along with the history of falls in the past 3 years.The groups were homogenous, with a predominance of female individuals, and mean ages of 81 (AD) and 79 (CG) years. A reduction in the R-R interval upon changing from the supine to the orthostatic positions was evident in both groups, but the AD group showed reduced parasympathetic components in the orthostatic position. For the frequency domain, a reduction in high frequency (HF) and increases in low frequency (LF) and in the LF/HF ratio were observed, suggesting increased sympathetic and reduced parasympathetic activities. The AD group presented more falls, whose incidence was associated with HRV components.Alzheimer's disease was associated with worse autonomic dysfunction, increased sympathetic activity and greater parasympathetic impairment, a high incidence of falls and interaction with HRV components.