By Benedict Tetzlaff-Deas Teens as young as 14 are getting hooked on ketamine and risk devastating their health – as one former user told the Mirror of the lasting damage caused to her body from the cheap party drug. Youths are said to be turning to the Class B party drug to cope with the “despair of mental illness”, but in the worst cases are developing severe addictions that mean they no longer have functioning bladders. The substance, invented as a horse tranquiliser, is now even being labelled the ‘cost of living drug’, as it is often cheaper to buy than alcohol. According to the latest Go…