Previous case reports showed that delirious mania could be one of the many neuropsychiatric presentations of Anti-N-methyl-d-aspartate receptor encephalitis (ANMDARE).
To evaluate the frequency of delirious mania and its associated factors in ANMDARE.
A prospective study, including all patients with ANMDARE admitted to the National Institute of Neurology and Neurosurgery of Mexico, from January 2014 to April 2019. The diagnosis of delirious mania was established when diagnostic criteria for mania and delirium were fulfilled simultaneously.
79 patients with definitive ANMDARE were included. Delirious mania was identified in 20 (25.3%) of these patients. Catatonia, psychomotor agitation, disinhibition, impulsivity, and grandiose delusions were significantly associated with delirious mania. Also, a lower frequency of EEG abnormalities, absence of extreme delta brush, and a shorter hospital stay was observed in these patients.
Delirious mania proved to be a frequent neuropsychiatric presentation of ANMDARE, and its presence should warn the physician about the possibility of this diagnosis. It was mainly associated with higher rates of catatonia, psychomotor agitation, disinhibition, and psychotic symptoms. The lack of recognition of delirious mania as a neuropsychiatric presentation in ANMDARE may be a source of diagnostic and therapeutic errors, as most physicians associate this with bipolar disorder.

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