Non-verbal. D-aspartate (NMDA) receptor (anti-NMDAR) encephalitis, caused by immunoreactivity against the NMDA receptor 1 (NR1) subunit of the NMDA receptor, is one of the most common autoimmune encephalitides, first described in 2007 by Dalmau and colleagues in which psychiatric and neurologic symptoms were found in women with ovarian teratomas.1 The condition was later confirmed to be not exclusively paraneoplastic. Later studies reported patients afflicted without tumor involvement.2,3 Although available data suggest the CDK4/6-IN-2 disease is more prevalent in adult women, and in the non-Caucasian population, the condition has been described in both genders, in multiple races, and throughout the lifespan.4,5 However, increasing case reports of anti-NMDAR encephalitis CDK4/6-IN-2 in the psychiatric literature have demonstrated the significant overlap between neurologic and psychiatric pathology associated with autoimmune encephalitis.6C10 The clinical progression of the encephalitis has also been more thoroughly defined, with a multiphase model currently in use.11 The prodromal phase is suggestive of a viral flu-like illness, in which fever, malaise, and fatigue may be prominent. This phase varies in duration and may also involve upper respiratory or gastrointestinal symptoms. The condition is often clinically recognized in the ensuing psychotic phase, in which delusions, hallucinations, paranoia, and agitation may be exhibited. During this phase, anti-NMDAR encephalitis is often misdiagnosed as a primary psychotic or substance-induced CDK4/6-IN-2 disorder. Following these psychotic symptoms is often the progression to a state in which catatonia, impaired attention, dyskinesias, and seizures may develop. In addition, significant autonomic instability, with wide-ranging fluctuations in body temperature, blood pressure, respiratory rate, and cardiac rhythm, may occur.12 It is important to note that anti-NMDAR cases may not follow a strict phasic progression as mentioned earlier and may not include all of the symptomatology IL1RB mentioned earlier, thereby complicating diagnosis. Indeed, as autoimmune etiologies of psychiatric symptoms continue to be better recognized as a whole, patient presentations that should prompt further immunologic evaluation have been identified. Herken and Pruss13 have described yellow flag and red flag symptoms that are particularly indicative of an autoimmune process. Decreased level of consciousness, abnormal postures/movements, autonomic instability, focal neurologic deficits, aphasia/dysarthria, and rapid progression of psychosis despite therapy, hyponatremia, catatonia, headache, and presence of other autoimmune disease were described as yellow flag (i.e., raising suspicion) indicators of an autoimmune process. Cerebrospinal fluid (CSF) pleocytosis and oligoclonal bands without infection, generalized seizures, faciobrachial seizures, suspected neuroleptic malignant syndrome (NMS), magnetic resonance imaging (MRI) abnormalities (mesiotemporal hyperintensities, atrophy pattern), and electroencephalogram (EEG) abnormalities (slowing, epileptic activity or extreme delta CDK4/6-IN-2 brush) are of even higher (red flag) concern indicators of potential autoantibody involvement. Identification of these characteristics is associated with earlier diagnosis, implementation of immunotherapy, and improved patient outcomes. In the following case report, we discuss a patient who presented to the emergency department (ED) with behavioral symptoms and who was later medically hospitalized with psychiatric and neurologic consultation. Described are the multiphase phenomena, as well as the coordination of the psychiatry, neurology, and internal medicine services in diagnosing the unusual symptoms of this still poorly understood disease entity. Patient details have been de-identified to ensure privacy. Case Report The patient was a 40-year-old African-American female without previous psychiatric history and a medical history of hypertension. She was brought to the ED by her family, who were concerned CDK4/6-IN-2 about the sudden onset of unusual behavior. She had been sent home from work earlier that day due to inability to complete her normal tasks. Her son noted that she was not making sense, being forgetful and not acting like herself. The patient reportedly smoked marijuana after she came home. However, her son indicated her behavior was odd even before her drug use and then worsened throughout the day, prompting medical attention. Her family reported a recent stressor of the death of her mother several months earlier..