Which of the following is NOT linked to chronic inflammation?

Chronic inflammation is a biological response that can contribute to various health conditions. Each of the first three options—arthritis, Alzheimer's disease, and cancer—has been extensively researched and found to have clear links to chronic inflammation.

Arthritis often involves inflammation of the joints, leading to pain and swelling. In the case of Alzheimer's disease, inflammatory processes in the brain can contribute to the neurodegeneration seen in this condition. Cancer exists in a relationship with inflammation, as chronic inflammation can promote the occurrence and progression of tumors.

On the other hand, while depression has various physiological and psychological factors contributing to it, the evidence linking it directly to chronic inflammation is less definitive and still a topic of ongoing research. While some studies suggest there may be a connection between increased inflammatory markers and depression, it is not as established or strong as in the other conditions listed. Thus, depression is often viewed as having several contributing factors that do not primarily include chronic inflammation as a core element.

This distinction illustrates why depression is not commonly classified in the same way as the others, making it the choice that is not clearly linked to chronic inflammation as the others are.