Which condition is characterized by neural plaques and a decline in cognitive abilities occurring after age 80?

Alzheimer's Disease is characterized by the presence of neural plaques and a significant decline in cognitive abilities, particularly in individuals over the age of 80. This neurodegenerative condition leads to progressive memory loss, disorientation, and a decline in the ability to perform daily tasks. The formation of amyloid plaques and neurofibrillary tangles in the brain is a hallmark of Alzheimer's, which disrupts cell-to-cell communication and ultimately results in the cognitive decline observed in affected individuals.

The other conditions listed do not specifically relate to the characteristic features of plaques and the age demographic mentioned. Anterograde amnesia focuses on the inability to form new memories after the onset of an amnesic event, rather than age-related cognitive decline. Autobiographical memory pertains to an individual's recollection of their life experiences and is not a diagnosis. Short-term memory loss can occur in various contexts and does not exclusively indicate Alzheimer's or imply the age range specified. Therefore, the defining characteristics of Alzheimer's Disease make it the answer that best fits the description provided in the question.