- Any medical or neurological problem that might affect interpretation of findings or safety of participation (e.g., blood dyscrasias, lymphomas, hypersplenism, endocrinopathies, renal failure or chronic obstructive lung disease, malignancy, neurological diseases of the brain, history of seizures or head trauma), low hemoglobin (Hb < 12 gm/dL in males, Hb < 10.5 gm/dL in females))