Identifying Correlates of Brain Microglial Activation in Neuropsychiatric Syndromes: a Dimensional Approach

Inclusion Criteria: * Must be between 18-80 years old * Males or females * Must be right handed * Must be able to sit unaccompanied for long periods of time with little body movement * Must be illicit drug free at time of scanning as appropriate (UDS negative), * Must be either healthy (without medical, neurological, psychiatric illness) or have a diagnosis of a neuropsychiatric syndrome (mood disorder, chronic pain syndrome, dementias, traumatic brain injury, substance/alcohol use disorder). * Healthy Control volunteers must be medication free (≥ 14 days) * Illicit drug free at time of scanning (verified by negative urine drug screen) Exclusion Criteria: * Must not be a smoker. * Females must not be pregnant or nursing. * Must not suffer from claustrophobia * Must not meet exclusion criteria for MRI scanning (i.e. non-fixed magnetisable objects) * Must not be PBR-28 low affinity binder (or using the \[11C\]ER176 study radiotracer) * Healthy control volunteers must not have on-going, chronic, or relapsing/remitting medical, psychiatric (absence of both DSM-IV Axis I and/or Axis II disorders), or neurological illness as determined by combination of history, medical record, and/or examination.