CNTNAP2 and Mental deterioration: Anti-CASPR2 autoantibody encephalitis (CASPR2 encephalitis) occurs typically in older men and is characterized by a wide range of syndromes, from limbic encephalitis with cognitive decline and seizures, cerebellar ataxia to Morvan syndrome, which includes peripheral nerve hyperexcitability, severe insomnia, and encephalopathy (Van Sonderen et al., 2016).