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Syncope is common in cognitive impairment and overlaps with unexplained falls. It is caused by transient cerebral hypoperfusion as a result of systemic hypotension. The main cause of syncope in cognitive impairment is neurocardiovascular instability (NCVI) or age-related hypotensive syndromes. The most common presentations of NCVI are orthostatic hypotension and carotid sinus hypersensitivity/syndrome occurring in over 70% of fallers with dementia. However, it is not known whether the neurodegenerative processes that occur in the common dementia subtypes are responsible for the increased prevalence of NCVI in cognitive impairment and dementia or whether the transient and chronic episodes of hypoperfusion caused by NCVI precede the hypometabolic and neurodegenerative changes in cognitive impairment and dementia.