After almost two decades, the FDA has granted conditional approval to a drug for the treatment of Alzheimer’ disease, called aducanumab. But the new drug, and its approval, is surrounded by controversy. Will the gamble pay off? Also, a clever upgrade to fog-collecting technology which could provide a water source in remote locations. And, potentially life-saving oxygen enemas? Kenneth Cukier hosts  For full access to The Economist’s print, digital and audio editions subscribe at economist.com/podcastoffer and sign up for our new weekly science newsletter at economist.com/simplyscience.   See acast.com/privacy for privacy and opt-out information.