The topic of peroxisome proliferator-activated receptor ligands typically involves a discussion of the lipid-lowering effects of fibrates and the blood sugar-lowering effects of thiazolidinediones. Palmitoylethanolamide has been shown to be effective in a number of chronic pain conditions both as an adjunct therapy to other pain medication and as a monotherapy. Fibromyalgia is a complex disease state that encompasses many different pain disorders, making diagnosis and treatment difficult. The presence of inflammatory cytokines is key to the nociception, allodynia, and hyperalgesia seen in fibromyalgia patients. The disabling motor disturbances seen in Parkinson disease are a result of the neurodegeneration of dopaminergic nigrostriatal neurons. The cause of the neurodegeneration is thought to be related to the activation of glial cells leading to inflammation. Traumatic brain injury has a high mortality rate and is associated with behavioral dysfunction, chronic pain syndromes, anxiety, memory, and/or learning deficits.