Following the USS Lantree's visit to the Darwin Genetic Research Station in 2365, the crew began to experience, according to Doctor Katherine Pulaski, "the rapid onset of geriatric phenomena." She explained that the first symptom of these phenomena was "sudden, acute arthritic inflammation, then the aging process accelerates."
Later in her investigation, Pulaski herself contracted the aging disease and began to rapidly age. When it was discovered that the aging process could be reversed through the transporter, she explained that "if I live through this, I'll have a much better understanding of geriatrics." (TNG: "Unnatural Selection")