Eligibility Details:  
        -  ELIGIBILITY CRITERIA FOR PART I SCREENING STUDY:
        INCLUSION CRITERIA:
        All Subjects (HIV-infected and HIV-negative Controls):
        While different individual HIV neurocognitive studies have specific selection criteria,
        especially related to HIV viral load and antiretroviral therapy, inclusion criteria for
        this overarching protocol will be flexible in order to identify the broadest base of
        potential enrollees possible.
          1. Men and women, 18 years of age and older
          2. Ability to sign informed consent by the subject
          3. At least seventh grade educational level and ability to speak, read, and understand
             English. Education level will be assessed by subject self-report. Because many of the
             neuropsychological subtests were validated using United States norms, subjects must be
             native English speakers or if foreign-born, demonstrate ability to understand the
             English language at the time of screening protocol consent and neuropsychological
             testing.
        HIV-infected Only:
          1. HIV-1 infection, as documented by OraQuick rapid test using venipuncture whole blood,
             or fingerstick whole blood done at screening; or with HIV-1/HIV-2 Multispot rapid test
             and Western Blot as determined by NIH Clinical Pathology Laboratory or Leidos
             Biomedical Research. Monitoring Laboratory.
          2. Outside primary medical doctor who provides care
        HIV-negative Controls Only:
        1.HIV-antibody negative
        EXCLUSION CRITERIA:
        Screening Study (all participants):
          1. Illness or other condition that, in the opinion of the PI, may interfere with study
             participation at the time of enrollment, including, but not limited to those listed
             below:
               1. CNS infections: this includes but is not limited to Varicella zoster virus (VZV)
                  encephalitis, CNS lymphoma and toxoplasmosis. Subjects who have recovered from
                  effectively treated CNS infections may be considered once they resume baseline
                  daily activities.
               2. Non-CNS opportunistic infections: subjects who recovered from or are completing
                  treatment for non-CNS opportunistic infections (OIs) (e.g., Pneumocystis
                  pneumonia, Candida esophagitis, or pulmonary TB) can be enrolled if they have
                  returned to self-reported baseline activity and functional level.
          2. Conditions other than HAND associated with cognitive impairment or dementia such as
             Alzheimer s, Parkinson s disease, head injury with loss of consciousness >30 minutes,
             untreated sleep apnea with day-time sleepiness, or seizure disorders. Subjects with a
             history of seizure disorder with no seizure activity that are on a stable,
             non-sedating anti-seizure regimen for >6 months may be enrolled.
          3. Concurrent severe, unstable psychiatric illness that, in the opinion of the
             investigators, may interfere with study participation and/or data interpretation.
             Subjects on psychotropic anxiolytic, attention deficit-hyperactivity disorder (ADHD),
             and other psychiatric medications may be included if clinically stable for >6 months.
          4. Concurrent substance abuse that, in the opinion of the investigators may interfere
             with study participation and/or data interpretation. Active substance abuse includes
             illegal drug use and/or excessive narcotic or alcohol use as determined by the
             investigator. Urine drug screen will be performed on all subjects at screening. Use of
             nicotine containing products will not be an exclusion criterion.
          5. Contraindication to MRI/ MRS scanning, including pacemakers or other implanted
             electrical devices, brain stimulators, some types of dental implants, aneurysm clips
             (metal clips on the wall of a large artery), metallic prostheses (including metal pins
             and rods, heart valves, and cochlear implants), implanted delivery pump, or shrapnel
             fragments. Patients requiring a low dose oral benzodiazepine for mild to moderate
             claustrophobia will be allowed to participate. Pregnancy testing will be performed in
             enrolled female participants 48 hours prior to any MRI.
          6. Medications: narcotics, psychiatric, and anti-seizure medications will not be allowed
             except under certain conditions as noted above. Corticosteroids may be permitted for
             subjects on stable short-term therapy without CNS disease (i.e., resolving
             Pneumocystis pneumonia). Participants must be willing not to take the following
             medications within 48 hours of neuropsychological testing : sedating antihistamines
             such as diphenhydramine, zolpidem and other drugs identified by the study team that
             are associated with altered alertness or impaired memory.
          7. Pregnant or Lactating women: Women of childbearing potential must have a negative
             serum or urine pregnancy test at the time of
        screening. Pregnancy testing will also be performed in enrolled female participants prior
        to any radiation exposure.
        ELIGIBILITY CRITERIA FOR PART II NATURAL HISTORY STUDY:
        INCLUSION CRITERIA:
        Natural History Study (HIV-infected Only):
        In addition to the inclusion criteria for the screening study (see above)
          1. Plasma HIV-RNA <50 copies/mm(3) or BLD for greater than one year. Patients who
             experience transitory episodes of an HIV viral load > 50 copies/mm (3) preceded and
             followed by plasma viremia < 50 copies/mm(3) may be included.
          2. At least one year of continuous ART
          3. Consent to store blood and tissue
          4. Willing to participate on this study for 5 years
        Natural History Study (Healthy Controls Only):
          1. Men and women, 18 years of age and older
          2. Ability to sign informed consent by the subject
          3. At least seventh grade educational level and ability to speak, read, and understand
             English. Education level will be assessed by subject self-report. Because many of the
             neuropsychological subtests were validated using United States norms, subjects must be
             native English speakers or if foreign-born, demonstrate ability to understand the
             English language at the time of screening protocol consent and neuropsychological
             testing.
          4. HIV-antibody negative
        PARTICIPANT EXCLUSION CRITERIA:
        In addition to the exclusion criteria from the screening protocol (see section above):
          1. Inability to refrain from use of anticoagulant/antiplatelet medication, such as
             dipyridamole (Persantine), clopidogrel (Plavix), dabigatran (Pradaxa), or warfarin
             (Coumadin) for at least 72 hours prior to invasive procedures (lumbar puncture [LP],
             lumbar drain).
          2. Prior or planned/anticipated exposure to radiation due to clinical care or
             participation in other research protocols, which would exceed the recommended
             acceptable annual limit of radiation exposure once accounting for the requirements of
             the current study.
          3. Pregnant or Lactating females are excluded due to exposure to the radioactive compound
             for PET/CT scans, which may be excreted in the breast milk and could be potentially
             harmful to breast-fed infants. There is also exposure to radiation from the CT part of
             the PET/CT scan and the lumbar puncture if done under fluoroscopy. Women of
             childbearing potention must have a negative serum or urine pregnancy 48 hours prior to
             any radiation exposure.
        EXCLUSION OF PREGNANT OR LACTATING WOMEN:
        The study requires exposure to high magnetic fields and irradiation, which could pose a
        risk to the fetus. Futher, we will be studying growth factors and inflammatory mediators in
        blood and CSF all of which will be affected by the state of pregnancy and then post partum
        state. Women who are lactating are excluded because the study may result in transfer of
        radioactive tracer in breast milk.
        EXCLUSION OF CHILDREN::
        Subjects younger than 18 years of age are excluded because the developing brain is not
        within the scope of this study.
        Department of Defense MRI-only Inclusion/Exclusion Criteria:
        Due to the nature of the military population, the ALLHANDS DOD protocol has some notable
        differences in the inclusion/exclusion criteria. Note that only HIV+ participants will come
        from the DOD.
          1. No ART use or HIV viral load level requirement.
          2. Outside primary medical doctor requirement not included as subjects are military
             beneficiaries who have primary medical care
          3. Illicit drug testing will not be performed for this study to avoid risk of inadvertent
             identification and disclosure of a positive result. Prior studies have shown drug use
             to be very low in this population.
          4. Head injury with loss of consciousness >30 minutes will be noted, but not an exclusion
             criterion.
          5. Untreated sleep apnea with daytime sleepiness will be noted, but not an exclusion
             criterion Sleep disorders were found to be prevalent among this population.