1. Dementia in HIV Patients of 60 Years of Age (K23 AG032872) from the National Institute on Aging of the National Institutes of Health
2. Cognitive Impairment in HIV over 60 Years of Age funded in part by the AIDS Research Institute at UCSF, Carl L. Gaylord Estate funds and by the UCSF-Gladstone Institute of Virology & Immunology Center for AIDS Research (CFAR, P30-AI027763)
3. Cognitive Health and Brain Vulnerability in Aging Insulin Resistant patients funded by the Larry L. Hillblom Foundation
4. Additional support is received from the UCSF General Clinical Research Center (GCRC) which is supported by NIH/NCRR UCSF-CTSI Grant Number UL1 RR024131.

The purpose of this study is three-fold:

1. To determine if insulin resistance causes a unique pattern of cognitive impairment or if it simply lowers the threshold for overlying neurodegenerative processes to present themselves.
2. To study the effects of HIV on cognition in people over 60 years of age.
3. To study the corresponding neurological changes (via MRI imaging and volumetric analysis).

To qualify for the study, you must meet these requirements:

1. HIV+
2. 60 or more years old
3. Have never had a brain infection
4. Do not have Hepatitis C infection
5. Do not have drug abuse

1. Metal in body
2. Pacemaker
3. Back pain that would prohibit lying on back for 2 hours
4. Have had a stroke
5. Have had a brain infection
6. Hepatitis C positive

All patients will be co-enrolled into the ADRC, which has the following exlusion criteria:

1. MMSE <15
2. Abrupt onset of cognitive impairment, ictal events or head trauma
3. Significant CNS effects of cerebrovascular disease
4. Known significant mass lesions on neuroimaging, hydrocephalus, demyelinating disease, focal inflammatory or infectious disease or recent or remote intracerebral hemorrahage
5. History of encephalitis or meningitis
6. Substance abuse (including alcohol) or dependence
7. Metabolic or systemic abnormailities wiht possibel impact on cognition
8. Active systemice illnesses such as cancer or end-stage cardiac insufficiency
9. Inability to cooperate with testing procedures

HIV patients will also be excluded if they have any past brain opportunisitic infection (e.g., cryptococcal meningitis, toxoplasmosis) or if IV drug use is the primary risk for contracting HIV infection.

1. Memory and thinking tests;
2. Neurological examination;
3. Brain MRI;
4. Fasting blood draw;
5. Oral glucose tolerance test (OGTT), if requested by Dr. Valcour;
6. Contact with a person who knows you well and can provide information about your memory;
7. Annual follow-up