Relationship between arterial stiffness and cognitive function in outpatients with dementia and mild cognitive impairment compared with community residents without dementia

BACKGROUND It is unclear whether the dementia patients with Alzheimer’s disease (AD) and vascular dementia (VaD) and mixed dementia (MIX, including AD and VaD) would have more developed arterial stiffness as compared with local residents without dementia. The aim of this study was to assess arterial stiffness and cognitive function in different types of dementia patients [AD, VaD, MIX and mild cognitive impairment (MCI)] and community residents without dementia. METHODS This was a single-center, cross-sectional observational study. We studied a cohort of 600 elderly outpatients with a complaint of memory loss, who were divided into four groups (AD, VaD, MIX and MCI). In addition, they were compared with 55 age-matched local residents without dementia (Controls). We assessed arterial stiffness by brachial-ankle pulse wave velocity (baPWV) and the global cognitive function by the Mini-Mental State Examination (MMSE). RESULTS The baPWV was higher in AD, VaD and MIX than in MCI and in Controls (P < 0.05). The baPWV was higher in MCI than in Controls (P = 0.021), while MMSE were compatible between them (P = 0.119). The higher baPWV predicted the presence of AD, VaD, MIX and MCI with the odds ratio of 6.46, 8.74, 6.16 and 6.19, respectively. In contrast, there were no difference in baPWV among three different types of dementia (P = 0.191). The linear relationship between baPWV and MMSE was observed in the elderly with MMSE ≥ 23 (R = 0.452, P = 0.033), while it was not in dementia patients (MMSE < 23). CONCLUSIONS The findings suggest that MCI and dementia patients have stiffer arteries as compared with age-matched local residents, although global cognitive function may be comparable between MCI and the local residents.

The development of arterial stiffness is caused by hypertension (HT), diabetes mellitus (DM), dyslipidemia, obesity and smoking, and is markedly affected by aging. The occurrence of cardiovascular diseases and stroke increases as the population ages, at least, due to the development of arterial stiffening with aging. Similarly, cognitive impairment is closely related to the arterial stiffening with aging.It is well established that arterial stiffness is an independent predictor of cardiovascular morbidity and mortality, particularly of stroke and coronary heart disease.^[1–4] Recent evidence indicates that systemic arterial stiffness is also related to cognitive decline in general population based on both cross-sectional and longitudinal epidemiological studies. For example, the recent systematic reviews and meta-analysis demonstrated that higher pulse wave velocity (PWV) predicted poorer cognitive performance and a steeper cognitive decline.^[5–9] Moreover, it was indicated that carotid-femoral PWV was a strong predictor of cognitive decline in the elderly, independently of other risk factors that could also affect cognition, such as HT, age or education.^[10,11] Similarly, an association between brachial-ankle PWV (baPWV) and poor cognitive function after adjustment for age, education and indices of atherosclerosis was observed in the Japanese general population.^[12,13]The number of dementia patients increases as the population ages. Alzheimer’s disease (AD) and vascular dementia (VaD) are common types of dementia, both of which are associated with aging. The pathologic features of AD are neurofibrillary tangles and brain beta-amyloid deposition.^[14–17] On the other hand, VaD is a type of dementia caused by cerebrovascular disorder, and its underlying pathology is heterogeneous, in which cerebral small vessel disease (SVD) is considered to be the most common type.^[18–20] The SVD dementia that develops as a result of arteriolosclerosis is called subcortical VaD, which is divided into two types: multiple lacunar infarct dementia when lacunar infarcts are the main cause, and Binswanger’s disease when white matter lesions are the main cause. In addition, complications and continuity between VaD and AD were noted, and mixed dementia (MIX) is the focus of attention. The pathophysiological feature of the MIX is characterized by having the features of both AD and VaD, and its prevalence is presumed to be significant, approximately 20%–40%.^[21] Thus, it is likely that patients with AD, VaD and MIX would have more developed atherosclerosis as compared with local resident without dementia. However, it is still unclear whether dementia patient with AD, VaD and MIX would have more developed central arterial stiffness as compared with local peers.The aim of the present study was to clarify the relationship between arterial stiffness, and different types of dementia patients (AD, VaD and MIX) and community-dwelling elderly without dementia.