This is a study to evaluate the feasibility and tolerability of low-rate continuous Cerebrospinal Fluid (CSF) sampling and to estimate the number of participants who exhibit severe baseline instability of CSF amyloid beta isoform Aß40 concentrations in healthy participants.

Inclusion Criteria:

• Must be in good health
• Must have a body mass index greater than or equal to 18 kg/m^2 and less than or equal to 30 kg/m^2

Exclusion Criteria:

• Is pregnant, nursing, or plans to become pregnant
• Has clinically significant cardiovascular, renal, hepatic, gastrointestinal (GI), neurological, endocrine, hematological, dermatological or metabolic disease, or clinically significant abnormalities, as determined by medical history, physical examination, electrocardiogram, vital signs, or laboratory tests
• Has a history of migraine headaches
• Has a history of recent lumbar CSF sampling within 3 weeks prior to screening, history of lumbar spine surgery, or chronic low back pain or injury
• Has an infection or inflammation of the skin in or in close proximity to the area of the lumbar puncture site
• Has a history of a seizure disorder
• Is noted to have papilledema or clinically significant focal neurological deficits at the screening physical examination, as well as abnormalities of CSF pressure on initial testing once access to the lumbar space is achieved
• Has absolute or relative anatomic abnormalities that would be a contraindication to lumbar puncture
• Is a heavy consumer of alcohol
• Has used nicotine in the past 6 months
• Has a history of a significant psychiatric disorder

Healthy volunteers from general population