The circadian rhythm of arterial blood pressure in Alzheimer's disease and vascular dementia.

Hypertension is considered a risk factor for stroke and dementia. Ambulatory blood pressure monitoring (ABPM) is a useful tool in the diagnosis and treatment of hypertension. This study aimed to evaluate blood pressure using ABPM, in 30 Alzheimer’s disease (AD) patients and 30 vascular dementia (VaD) patients in comparison with 30 healthy controls. BP was recorded every 15 min from 6 AM to 10 PM, and every 30 min from 10 PM to 6 AM. Mean systolic (SBP) and diastolic (DBP) blood pressure during daytime, nighttime, diurnal index, pulse pressure, and heart rate were extracted from the ABPM recordings. VaD patients presented higher SBP values compared to AD patients and healthy controls. DBP values in the AD group were the lowest, while VaD patients presented the highest DBP values, including day and nighttime. Mean arterial pressure values were also the highest in the VaD group, while AD patients had similar values with the control group. The VaD patients presented the lowest systolic diurnal index compared to AD patients and controls. The mean pulse pressure and nighttime pulse pressure values were higher in both groups of dementia patients when compared with the control group. Increased SBP, pulse pressure, and alteration in the circadian pattern with the highest incidence of the non-dipper and reverse dipper patterns were found in patients with dementia when compared with the healthy elderly. Also, decreased values of DBP were found in AD patients, especially during the night period.