Interestingly, overexpression of extracellular HMGB1 has been observed in clinical and preclinical studies on Parkinson's disease (10), stroke (11), traumatic brain injury (12), epilepsy (13), autism (14), depression (15), multiple sclerosis (16), and amyotrophic lateral sclerosis (17). This evidence concerns the gene HMGB1 and depressive disorder.