C4B and psychiatric disorder: On the other hand, due to the overexpression of complement components in Toxoplasma-infected brain [53,63], and the upregulation of C1q, C3, and C4b in some mental disorders including schizophrenia, alzheimer’s disease, aging and multiple sclerosis [54,137,138,139,140], it could be interesting to focus on therapeutic studies that share more information regarding the possible correlations between parasitic disease including toxoplasmosis and mental disorders and their association with the complement system.