What symptom is characterized by a deficit in cognitive function that cannot solely be ascribed to aging?

Dementia is characterized by a decline in cognitive function that significantly interferes with daily living and cannot be attributed entirely to the normal aging process. It encompasses a range of symptoms associated with the impairment of memory, reasoning, language, and other cognitive skills. These impairments are typically progressive and affect a person's ability to perform everyday activities, indicating a more severe level of cognitive decline than would be expected from normal aging.

In contrast, Alzheimer's disease is a specific form of dementia and represents the most common cause of dementia but does not define the broader category that includes other types as well. Mild Cognitive Impairment is also a transitional stage often preceding dementia, marked by noticeable memory problems that do not entirely impair daily functioning. Depression can mimic cognitive impairment and lead to difficulties in concentration and memory but is primarily an affective disorder rather than a direct cognitive deficit.