A bit of convoluted neuroscience irony. "20 years 9,321 bottles of booze 68,237 brain cells later". The writers inadvertently got the brain cell loss right. It was long believed that alcoholism kills a lot of brain cells; we now know that is not true, the cells remain alive albeit temporarily impaired. The writers assumed 63,237 brain cells are a lot, that number is insignificant. The brain has over a million times that number of cells. So, the writers inadvertently, accurately tell us that Vimes had no appreciable loss of brain cells.