<prompt> True about dementia is AEHallucination are not commonClouding of consciousness is commonNootropics have limited roleAll  <response>: B i.e. Clouding of consciousness is common Clouding of consciousness is a characteristic feature delirium is helpful in differentiating it from dementiaQ. Two most common causes of dementia are Alzheimers multi infarct; both of which are irreversible. 