What’s the difference between normal forgetfulness, mild cognitive impairment, and Alzheimer’s disease?

Occasionally forgetting a name and recalling it later can occur with normal aging. Mild cognitive impairment, or MCI, means a measurable decline beyond what is expected, while independence in most everyday activities is largely preserved. Dementia describes cognitive impairment substantial enough to interfere with independent daily life. Alzheimer’s disease is a specific disease that can cause MCI or dementia, not a synonym for every memory complaint. Other conditions can cause dementia, and more than one process can be present at the same time.[1][2][3]

The distinction requires more than a single online memory test. Persistent worsening, repeated questions or trouble managing familiar tasks deserves assessment, including a history from the person and, when possible, someone who knows them well. Sleep problems, depression, medications and medical conditions can contribute to cognitive symptoms. Not everyone with MCI progresses to dementia; some remain stable or improve when contributing problems are addressed. A sudden change in attention or confusion is different from gradual decline and needs prompt medical evaluation rather than being labeled normal aging.[1][2][3]