Which of the following best describes the typical lifespan of someone diagnosed with Alzheimer's disease?

The range of 1 to 15 years for the lifespan of someone diagnosed with Alzheimer's disease, with an average of 4 to 8 years, is consistent with current understanding of the disease's progression. Alzheimer's is characterized by gradual cognitive decline and physical deterioration that usually leads to complications.

Research indicates that the average survival time after diagnosis typically falls within this range, with individual durations varying widely based on numerous factors, including age at diagnosis, overall health, and presence of other medical conditions. The average of 4 to 8 years reflects the typical disease progression, during which symptoms gradually worsen, impacting daily functioning and quality of life.

In contrast, the other options present unrealistic timelines or outcomes. The notion of a lifespan of 20 to 30 years does not align with clinical findings as Alzheimer's is a degenerative disease that tends to progress over a relatively shorter period. Similarly, the idea of significant improvement over 5 to 10 years contradicts what is typically observed in patients, as Alzheimer's leads to a decline in cognitive and functional abilities rather than improvement. Lastly, the claim of achieving a lifespan of 2 to 7 years without treatment interruption could be misleading, as treatment can help manage symptoms but does not alter the overall trajectory or lifespan significantly