Cognitive Decline in Older Adults

Cognitive decline is a clinical syndrome, not a diagnosis and not an automatic consequence of aging. The first task is to determine whether the change is acute and fluctuating, chronic and progressive, or a subjective concern without objective impairment. The next tasks are to establish functional stage, describe the cognitive-behavioral pattern, and identify the disease or diseases affecting the brain. Alzheimer disease is now defined biologically: an abnormal Core 1 biomarker—amyloid PET, qualifying CSF measures, or an accurate plasma assay such as p-tau217—establishes that Alzheimer pathology is present somewhere along the disease continuum [1]. That result does not, by itself, tell you the patient's stage, explain every symptom, or establish eligibility for treatment. Function still determines whether the person has transitional decline, MCI, or dementia, and the syndrome pattern helps identify alternatives such as dementia with Lewy bodies or vascular cognitive impairment.