TNF and Cognitive impairment: Furthermore, given that ammonia acts in concert with neuroinflammation to induce cognitive impairment in HE17 and that HE is also characterised by cerebral oedema18,19, we determined the cerebral water content20,21, brain inflammatory factors (tumour necrosis factor-α [TNF-α] and interleukin [IL]-1β)22,23, and serum ammonia level to evaluate the disease severity.