Amy Schleunes in The Scientist:
The first thing Martha Carlin noticed was a faraway look in her husband’s eyes. It was a subtle change, she says, something only a wife would see. She happened to be reading Lucky Man by Michael J. Fox at the time, and began to wonder about some of the symptoms she’d observed in her husband: his loss of facial expressions, his quivering pinky finger, his trembling tongue. An appointment with an internist led to an appointment with a neurologist, who confirmed Carlin’s worst fears. In the fall of 2002, her husband John was diagnosed with Parkinson’s disease. He was 44 years old.
Carlin spent the next seven years reading everything she could find on Parkinson’s. A consultant skilled at identifying breakpoints in businesses, Carlin concluded that the disease is “a systems problem,” she says, a collapse of the body’s ecosystem. Much of what she had learned implicated the gut, including the finding that constipation is one of the earliest symptoms of Parkinson’s, often emerging 10 years or more before a diagnosis. In late 2014, Carlin read a study that identified a specific imbalance in the composition of Parkinson’s patients’ gut microbiomes, suggesting that changes in the gut microbiota could be an important biomarker for the disease. “That is it,” she remembers thinking. “The gut is the general ledger of the body.”
She quit her consulting job and enlisted the help of Jack Gilbert, a microbiome expert then at the University of Chicago. Carlin paid Gilbert, who serves on The Scientist’s editorial advisory board, to analyze her and her husband’s stool samples, and also donated $30,000 to cover part of the salary of one of his postdocs. Together, she and Gilbert pored over the microbiome literature. They kept coming across mentions of certain microbial genes that were overexpressed in conditions such as Parkinson’s and autism, suggesting “functional similarities at a systems level,” Carlin says. It seemed logical to her that investigating such complex conditions would require looking at the whole community of bacteria in the living system.