This study plans to examine biological bases of cognitive aging. The goals of the study are to better understand how immune system markers, measured in the blood and in the spinal fluid, are related to clinical features of aging over time. The study also aims to better understand how different types of biomarkers may relate to immune health and the aging process. This research may ultimately help us better understand what puts individuals at risk for cognitive decline and for Alzheimer's disease.

Inclusion Criteria:

1. Between ages of 60-89
2. Have a reliable study partner who has frequent contact with the subject (i.e., at least twice per month) and is able to provide information about functional abilities
3. Mini Mental State Examination (MMSE) >23
4. Clinical Dementia Rating (CDR) global score of 0
5. No informant report of significant cognitive decline in prior year
6. No evidence from the screening visit suggesting a neurodegenerative disorder (per team neurologist)
7. Willingness to complete both baseline and 2-year follow-up procedures

Exclusion Criteria:

1. Major psychiatric disorder (e.g. schizophrenia, bipolar disorder, untreated major depression within past year)
2. Neurological conditions affecting cognition (e.g. Parkinson's disease, epilepsy (onset prior than 2 years ago), head trauma with loss of consciousness >5 min within past two years, large vessel infarct, mild cognitive impairment, or dementia)
3. CNS immune conditions and other conditions affecting cognition (e.g., multiple sclerosis, paraneoplastic encephalitides; Hashimoto's encephalopathy; systematic lupus erythematosus)
4. Systematic illness (e.g.,current cancer, renal failure, respiratory failure)
5. Substance abuse/dependence (DSM-V criteria)
6. Current medication use likely to affect CNS (e.g., long-acting benzodiazepines, neuroleptics in the phenothiazine and haloperidol families)
7. Current medication use that precludes lumbar punctures (e.g. anticoagulants, antiplatelets, heparin shots, or some other blood thinner medications: Warfarin [coumadin], Pradaxa [dabigatran], Xarelto [rivaroxaban]. Eliquis [apixaban], or Plavix [clopidogrel].
8. Significant sensory or motor deficits that would interfere with cognitive testing
9. Factors that preclude MR imaging (e.g., pacemaker)
10. Factors that preclude lumbar puncture

Healthy older adults