The objective of this study is to determine the effects of cerebrospinal fluid sampling rate on biomarker levels of young, healthy volunteers.

Inclusion Criteria:

• Age is between 18 and 50 years, inclusive
• Judged to be in general good health based on medical history, physical exam, neuro exam, vital signs, lab profile and ECG

Exclusion Criteria:

• Positive urine drug screen for drugs of abuse
• History of bleeding disorder or deep vein thrombosis
• History of migraine or other types of headache more than twice/month, history of spinal disc disease or chronic significant low back pain
• Use of blood thinning compounds within 10 days of lumbar drain placement
• Finding on head CT that contraindicates lumbar puncture
• History of spinal surgery
• Use of tobacco/nicotine containing products within 6 month period prior to initial lumbar drain placement

Community sample