(Abstract shortened by UMI.) / The conclusion of the studies reported herein can be summarized as follows: (1) PI in TCD correlates well with WMC volume and helps to differentiate those with and without WMC in stroke patients. (2) Post-stroke cognitive complaints are not related to severity of WMC among lacunar stroke patients. (3) The ARWMC scale correlates with objective cognitive performances and the operational definitions of ARWMC scale improves inter-rater reliability on CT. (4) Cognitive impairment in patients with confluent WMC is mediated by global and frontal cortical atrophy. Predictors for cognitive progression are cortical atrophy, absence of hyperlipidemia, low BP, and low cognitive scores. / With an aging population, prevalence of dementia is expected to escalate in the coming decades. The burden is especially great in developing countries like China. Similar to Alzheimer's pathology (e.g. amyloid plaque), age-related white matter changes (WMC) are important substrates of dementia. Since WMC are considered to be of ischemic origin, dementia related to WMC is believed to be more preventable than Alzheimer's disease. Yet, studies focusing on WMC have been relatively few. The thesis will cover 4 aspects of WMC and cognitive impairment. / Xiong, Yunyun. / Adviser: Vincent Mok. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 198-244). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; some appendixes in Chinese.