Cognition is impaired in patients with Alzheimer's disease and related disorder (ADRD). The deficits in AD involve verbal and visual memory, and language disturbances in early stages. Cognitive deficits in vascular dementia are variable and overlap with both AD and other dementias. Cognitive deficits in dementia with Lewy bodies involve significant attentional impairment and visual-spatial dysfunction. Cognitive deficits in frontotemporal dementias involve executive function. An assessment of cognition is recommended during initial assessment of patients with dementia. ChEIs and memantine are currently the best drugs available for symptomatic treatment of cognitive decline in patients with ADRD.