As a result of the studies, it has been hypothesized that the neuro-inflammation caused by <i>Toxoplasma gondii</i> may be responsible for the development of various neurodegenerative diseases.<h4>Objective</h4>Serum samples of 300 patients with neurodegenerative diseases and 100 healthy volunteers were evaluated for the presence of <i>Toxoplasma gondii</i> IgG and IgM antibodies by Electrochemiluminescence method. The gene discussed is CD40LG; the disease is neurodegenerative disease.