QT dispersion and heart rate variability abnormalities in Alzheimer's disease and in mild cognitive impairment.

OBJECTIVES: To investigate the effect of cardiovascular
changes (i.e., QT interval, QT dispersion (QTD), heart rate
variability (HRV), and other cardiovascular measures) in
subjects with Alzheimer’s disease (AD) and mild cognitive
impairment (MCI).
DESIGN: Each subject underwent clinical and cognitive
examination, a structural brain imaging study, echocardio-
Doppler, electrocardiogram (ECG), HRV analysis using
24-hour ECG monitoring, and 24-hour blood pressure
monitoring.
SETTING: Community population-based sample of patients
admitted to an AD center for investigation of cognitive
disturbances.
PARTICIPANTS: Thirty-three subjects with AD, 39 subjects
with MCI, and 29 cognitive healthy subjects (controls)
matched for demographic characteristics, hypertensive condition,
smoking habits, and laboratory parameters were
enrolled consecutively.
MEASUREMENTS: Clinical and cognitive examination,
structural brain imaging study, echocardioDoppler, ECG,
HRVanalysis using 24-hour ECG monitoring, and 24-hour
blood pressure monitoring.
RESULTS: QTD and QT corrected dispersion mean values
were significantly higher in patients with AD than in patients
with MCI and controls and higher in patients with
MCI than in controls. HRV time and domain parameters
were lower in patients with AD than in patients with MCI
and controls. No difference in other cardiovascular measures
was found. QTD and HRV were found to be significantly
correlated with the degree of cognitive impairment.
CONCLUSION: These findings support the presence of a
peculiar neuroanatomic dysfunction in patients with AD
and MCI that parallels the disease progression. These noninvasive
parameters might prove to be powerful predictive tools in the worsening of cognitive function and mortality
risk.