A Longitudinal Natural History Study of Immune Biomarkers in Neuropsychiatric Illness

* INCLUSION CRITERIA: At the time of enrollment: * Participants must be 1 month or above in age. * Participant biospecimens must be physically located in the United States, or its territories or freely associated states * Participants must have a neuropsychiatric illness of possible neuroinflammatory, or post-infectious etiology based on clinical report and findings from the referring facility/provider. To include one or more of the following: * known or suspected infection or inflammation of the nervous system, * new-onset post-infectious neuropsychiatric symptoms, * new or recurrent neuropsychiatric symptoms in the setting of a diagnosed autoimmune disease or proinflammatory disease state (e.g. systemic lupus erythematosus, sarcoidosis, Sjogren s, Down Syndrome), * new-onset neuropsychiatric symptoms within 5 years of a cancer diagnosis, * new-onset neuropsychiatric symptoms in the context of immune checkpoint inhibitor therapy, * new-onset neuropsychiatric symptoms in the setting of a known or clinically supported primary immune deficiency, * subacute onset psychiatric symptoms with cognitive impairment or personality change defined as a progression from baseline to functionally impaired within 3 months of the onset of symptoms, * or have a typical psychiatric presentation with neuroimaging, CSF, or laboratory findings suggestive of neuroinflammatory process At the time of enrollment participants or surrogates will: * be willing to participate in the protocol s procedures, unless clinically contraindicated, * provide informed consent, either directly or via an appointed legally authorized representative, * be willing to consent to secondary use of clinical data and biological samples collected at and prior to the time of their enrollment EXCLUSION CRITERIA: Participant currently under involuntary commitment/hold.