Cancer Cachexia Linked to Brain-Immune System Interaction in New Study

New research published in Science sheds light on cancer cachexia, a condition characterized by apathy and lack of motivation in cancer patients. This condition, which also reduces patients’ ability to tolerate cancer treatments, has been linked to a connection between the brain and the immune system. The study was conducted by Tobias Janowitz of Cold Spring Harbor Laboratory and Adam Kepecs of Washington University School of Medicine in St. Louis. 

Cancer cachexia often manifests as emotional and physical disengagement. “Many patients complain of symptoms in that category,” explains Janowitz. Patients may lose interest in activities they once enjoyed or feel indifferent toward favorite meals or spending time with loved ones. These changes are now understood to be biologically driven rather than solely emotional responses to illness.

The researchers found that cachexia disrupts dopamine production in certain brain areas. Dopamine, often referred to as the brain’s “feel-good” chemical, plays a key role in motivation. In mice with cachexia, elevated levels of the immune protein IL-6—released during inflammation—were observed in the brain and body. Reducing IL-6 signals or increasing dopamine levels restored motivation in these mice, making them less sensitive to effort when seeking food.

“We discovered a full brain circuit that senses inflammation in the bloodstream and sends signals that reduce motivation,” Kepecs says. “This reveals that apathy isn’t just an emotional or psychological reaction to cachexia—it’s built into the biology of the disease.”

The study suggests that existing antibody treatments targeting IL-6 could be repurposed to improve patients’ quality of life by alleviating cachexia symptoms. “Our goals are to make patients feel better and to treat the cancer better,” Janowitz explains.