Aggregate cardiovascular risk and changes in cognition,brain structure and function in older adults.
详细信息
文摘
Background: As the population ages,the prevalence of cognitive impairment and dementing illness in the elderly is expected to dramatically grow. Evidence shows that vascular risk factors such as hypertension,diabetes,dyslipidemia,smoking,and obesity are among important modifiable risk factors associated with risk of cognitive impairment and dementia. Cardiovascular CV) risk factors are highly prevalent in older adults and they rarely exist alone. While each individual CV risk factor can have deleterious impact on cardiovascular and cognitive health,it is usually a combination of several risk factors that act as not only a simple additive effect but also a multiplicative effect to impose the greatest risk of cardiovascular diseases and dementia to the individual. Although the relationship between CV risk factors and cognitive impairment and dementia in the elderly is established,the mechanisms linking them are just beginning to be elucidated. The aims of this dissertation were to investigate the associations between aggregate CV risk and cognitive functions,brain structural and functional changes in older adults. Methods: The study sample is from the Baltimore Experience Corps Trial BECT) and the Brain Health Study,a subsample of BECT. Framingham General Cardiovascular Risk Profile was used to characterize individuals aggregate CV risk. Domains of cognitive functions including psychomotor speed,episodic memory and executive function were assessed. Brain volumes of regions of interest were obtained from structural brain imaging. Functional brain imaging with the Flanker task were also collected. Results: First,it showed higher aggregate CV risk was associated with poorer psychomotor speed cross-sectionally and more rapid decline in psychomotor speed over 2 years. Second,it revealed that higher aggregate CV risk was associated lower parietal lobe volume cross-sectionally and greater atrophy rate of thalamus over 1 year. Third,it showed higher CV risk was associated with increased fMRI activity in left parietal region. Moreover,the correlation between CV risk and activation in the left parietal region was increased when the contrast of task difficulty was parametrically increased. In summary,aggregate CV risk was associated with brain structures and functions involved in the attentional network. These findings may provide important sights into the convergent pathophysiology underlying cardiovascular risk,which emphasize the role of cerebral hypoperfusion,white matter integrity/myelin breakdown and the attentional networks.