Vascular Compliance is Reduced in Vascular Dementia and not in Alzheimer's
Vascular Compliance is Reduced in Vascular Dementia and not in Alzheimer's
Objective: to determine whether functional changes in the vasculature differ between Alzheimer's disease (AD) and vascular dementia (VAD).
Design: we determined vascular stiffness in patients with a clinical and radiological diagnosis of either AD or VAD and compared them to normal age- and sex-matched controls.
Methods: In all, 16 patients with late onset AD, 13 subjects with VAD and 16 age- and sex-matched controls were recruited to this study. Central arterial compliance (CAC), augmentation index (AI) and pulse wave velocity (PWV) (measures of arterial stiffness) were measured.
Results: the mean age was 77.7 ± 8.3 years (mean ± SD) in the AD group, 79.7 ± 8.9 years in the VAD group and 76.4 ± 6.9 in the controls (P = 0.44). CAC was significantly lower in subjects with VAD compared to both the AD and the control groups (0.57 ± 0.46 ml/mm Hg versus 1.12 ± 0.57 and 1.1 ± 0.47 ml/mm Hg respectively, P = 0.01). AI was significantly higher in the subjects with VAD compared to both the AD and the control groups (13.3 ± 9.0 versus 3.5 ± 11.4 and 4.2 ± 9.7% respectively, P = 0.03). PWV in the muscular and elastic arteries were not statistically different between the three groups but tended to be highest in the VAD group for carotid-radial measurements.
Conclusions: the reduced CAC and increased AI in VAD subjects indicate that the disease process is associated with less vascular compliance of the large elastic arteries in these patients, but not in patients with AD.
Dementia is defined as a decline in cognitive function that may result in an impaired function in daily living. The prevalence of dementia is 1% in 60-year-olds and rises to 30% in the 85-year-old age group. Vascular disease and its principal risk factors have been found in population studies to be important associations of the two most common causes of age-associated dementia, Alzheimer's disease (AD) and vascular dementia (VAD), respectively. A diagnosis of VAD is made if dementia results from ischaemic, haemorrhagic, or ischaemic-hypoxic brain lesions especially in the presence of a history of hypertension, ischaemic heart disease, transient cerebrovascular, and peripheral vascular disease.
AD is a gradually progressive dementia of insidious onset, which occurs in the absence of other diseases that could account for the cognitive deficits. Although certain diagnostic criteria emphasise that AD is a diagnosis of exclusion with regard to vascular disease; vascular factors may also have a role in late-onset AD.
Decreased compliance of the central arterial vasculature changes the blood pressure and flow dynamics with significant impact on the cardiac contractility, coronary and cerebrovascular perfusion. Other measures related to vascular compliance include pulse wave velocity (PWV) and augmentation index (AI).
Recent studies have shown that arterial stiffness is associated with cognitive decline, and that for each 2-m/s increase in PWV there is an increased risk of both types of dementia, the adjusted odds ratio (OR) being 1.73 (95% CI 1.27-2.47) for AD and 3.52 (95% CI 1.87-8.05) for VAD.Scuteri et al. showed that worsening arterial stiffness as measured by PWV was more evident in subjects with cortical atrophy than in patients with subcortical microvascular lesions or controls (P < 0.05), and that higher PWV was associated with cognitive impairment, greater personal dependency, independent of other major modifiable cardiovascular risk factors and medications use. Both AD and VAD have significant vascular risk factors. A recent study by Bateman et al. showed that early VAD is characterised by normal cerebral blood flow and increased pulsation, while early AD is characterised by reduced blood flow and reduced compliance. Nagai et al. showed a relationship between PWV and cognitive decline in non-VAD.
The objective of this study was to assess arterial compliance (AC) in subjects with AD and VAD compared to age- and sex-matched controls.
Abstract and Introduction
Abstract
Objective: to determine whether functional changes in the vasculature differ between Alzheimer's disease (AD) and vascular dementia (VAD).
Design: we determined vascular stiffness in patients with a clinical and radiological diagnosis of either AD or VAD and compared them to normal age- and sex-matched controls.
Methods: In all, 16 patients with late onset AD, 13 subjects with VAD and 16 age- and sex-matched controls were recruited to this study. Central arterial compliance (CAC), augmentation index (AI) and pulse wave velocity (PWV) (measures of arterial stiffness) were measured.
Results: the mean age was 77.7 ± 8.3 years (mean ± SD) in the AD group, 79.7 ± 8.9 years in the VAD group and 76.4 ± 6.9 in the controls (P = 0.44). CAC was significantly lower in subjects with VAD compared to both the AD and the control groups (0.57 ± 0.46 ml/mm Hg versus 1.12 ± 0.57 and 1.1 ± 0.47 ml/mm Hg respectively, P = 0.01). AI was significantly higher in the subjects with VAD compared to both the AD and the control groups (13.3 ± 9.0 versus 3.5 ± 11.4 and 4.2 ± 9.7% respectively, P = 0.03). PWV in the muscular and elastic arteries were not statistically different between the three groups but tended to be highest in the VAD group for carotid-radial measurements.
Conclusions: the reduced CAC and increased AI in VAD subjects indicate that the disease process is associated with less vascular compliance of the large elastic arteries in these patients, but not in patients with AD.
Introduction
Dementia is defined as a decline in cognitive function that may result in an impaired function in daily living. The prevalence of dementia is 1% in 60-year-olds and rises to 30% in the 85-year-old age group. Vascular disease and its principal risk factors have been found in population studies to be important associations of the two most common causes of age-associated dementia, Alzheimer's disease (AD) and vascular dementia (VAD), respectively. A diagnosis of VAD is made if dementia results from ischaemic, haemorrhagic, or ischaemic-hypoxic brain lesions especially in the presence of a history of hypertension, ischaemic heart disease, transient cerebrovascular, and peripheral vascular disease.
AD is a gradually progressive dementia of insidious onset, which occurs in the absence of other diseases that could account for the cognitive deficits. Although certain diagnostic criteria emphasise that AD is a diagnosis of exclusion with regard to vascular disease; vascular factors may also have a role in late-onset AD.
Decreased compliance of the central arterial vasculature changes the blood pressure and flow dynamics with significant impact on the cardiac contractility, coronary and cerebrovascular perfusion. Other measures related to vascular compliance include pulse wave velocity (PWV) and augmentation index (AI).
Recent studies have shown that arterial stiffness is associated with cognitive decline, and that for each 2-m/s increase in PWV there is an increased risk of both types of dementia, the adjusted odds ratio (OR) being 1.73 (95% CI 1.27-2.47) for AD and 3.52 (95% CI 1.87-8.05) for VAD.Scuteri et al. showed that worsening arterial stiffness as measured by PWV was more evident in subjects with cortical atrophy than in patients with subcortical microvascular lesions or controls (P < 0.05), and that higher PWV was associated with cognitive impairment, greater personal dependency, independent of other major modifiable cardiovascular risk factors and medications use. Both AD and VAD have significant vascular risk factors. A recent study by Bateman et al. showed that early VAD is characterised by normal cerebral blood flow and increased pulsation, while early AD is characterised by reduced blood flow and reduced compliance. Nagai et al. showed a relationship between PWV and cognitive decline in non-VAD.
The objective of this study was to assess arterial compliance (AC) in subjects with AD and VAD compared to age- and sex-matched controls.