Altered blood pressure (BP) and heart rate variations (HRVs) have been reported in Alzheimer's disease (AD). However, it is unclear how these two manifestations are associated with AD. Therefore, the objective of this study was to investigate BP and heart rate variability in AD compared to that in normal controls, patients with subjective memory impairment (SMI), and patients with mild cognitive impairment (MCI).

Case-control comparisons were made among AD ( n =37), MCI ( n =24), SMI ( n =17), and controls ( n =25). All patients underwent clinical and neuropsychological assessments with 24-h ambulatory BP and Holter monitoring.

Patients with AD had higher pulse pressures than those in other groups. In addition, AD patients experienced blunted nocturnal BP dipping associated with declining cognitive status. AD patients also had larger ranges of HRV in parasympathetic domains compared to other groups, especially at night.

Our results suggest that diurnal sympathetic and parasympathetic cardiac variability were significantly disturbed in mild cholinesterase-naïve AD patients. This may be an indirect sign of disturbed integrity to the sleep-wake cycle in mild AD.