Inflammation

« Back to Glossary Index

Inflammation is a coordinated biological response of the immune system to infection, injury, cellular damage, or other threats, designed to protect the body and support repair. Immune cells communicate through signaling molecules, including cytokines, which can alter blood flow, recruit other immune cells, help clear pathogens or damaged cells, and affect activity throughout the body and brain. Acute inflammation is usually temporary and protective, subsiding when the threat has passed. Chronic low-grade inflammation, by contrast, involves persistent, less intense immune activity that may occur without the redness, heat, swelling, or pain we commonly associate with an injury. Researchers can detect systemic inflammation by measuring biomarkers in the blood, such as C-reactive protein (CRP) and particular cytokines.

Inflammation also interacts with the body’s stress-response system, metabolism, sleep, and circadian rhythms. Chronic psychological stress, trauma, sleep disruption, and metabolic dysfunction have all been associated with changes in inflammatory signaling. In turn, inflammatory signaling can affect the brain and is being studied for possible relationships with mood, cognition, energy, and behavior.

Researchers have found altered inflammatory markers in several serious mental illnesses (SMI), including bipolar disorder. But the relationship is complex: inflammation may contribute to psychiatric symptoms, result from the illness or its associated stresses and behaviors, reflect other underlying processes — or work in both directions. Its precise role remains under investigation.