A biological mechanism has been suggested to contribute to development of cerebral dysfunction in the patients. According to the prevailing Trojan Horses hypothesis circulating lymphocytes cross the blood brain barrier carrying HCV to the central nervous system and virus is subsequently replicated in the macrophages and the microglia in brain as a separate compartment. As part of the immunological response to viral replication, neurodegenerative processes takes place with a harmful effect on the neural circuit and cerebral function. Identification of HCV RNA negative strand, a replication product, in brain tissue from HCV patients, as part of autopsy studies, supports the hypothesis. Moreover, HCV patients have also been observed with abnormal metabolic concentrations in the frontal white substance and the basal ganglia by MRI spectroscopy compared to control groups.