Neuroinflammation

Neuroinflammation is an inflammatory response within the brain or spinal cord, driven mainly by microglia and astrocytes rather than by the white blood cells of the rest of the body.

The nervous system sits behind the blood-brain barrier and has its own immune machinery. When infection, injury, toxins or protein deposits disturb it, microglia activate, astrocytes change shape and both release cytokines, chemokines and reactive oxygen species. In the short term this response clears debris and limits damage. When it persists, it can harm neurons and synapses, and sustained neuroinflammation is now recognized as a contributor to Alzheimer's disease, Parkinson's disease, multiple sclerosis, depression and the after-effects of concussion.

It is assessed indirectly with PET tracers that label activated microglia, with cytokine measurements in cerebrospinal fluid and, in research, with postmortem tissue. Cannabinoid signaling is one of the pathways that regulates glial activation, and CBD has a substantial body of preclinical research in neuroinflammation models; disease-specific efficacy in people has not been established, and no approved use exists for that purpose.