C asey Lynch, CEO and cofounder of San Francisco-based Cortexyme, has been fascinated by Alzheimer’s disease throughout her career, even dating back to her graduate work at UCSF. And while other biotech and pharmaceutical companies have been needling away at the problem (without much success) for more than two decades, largely by looking to beta amyloid and tau proteins as the culprit, Lynch has long had the gut feeling that there was something else going on behind the scenes. As it turns out, she was right — looking at years of research, mounting evidence shows that a bacterial infection in the brain is at the root of Alzheimer’s disease.

Simultaneously, UCSF psychiatrist Dr. Stephen Dominy was working with patients with HIV and dementia, and was therefore especially interested in infectious causes of neurological disease. Dominy’s research led him to discover a pathogenic bacteria in the brain of patients, the two met each other through investment group Life Science Angels, and the seed for Cortexyme was planted. Cortexyme can now identify the bacteria in the cerebrospinal fluid of people with Alzheimer’s. Cortexyme, which operates in lab space at JLABS, a nonprofit run by Johnson & Johnson, has now proven this correlation between the bacteria and the disease in the brains of mice as well as aged dogs. The company began Phase I human clinical studies in December…