Robin McKie, the Observer’s science and environment editor, discusses an innovative drug that may soon offer ways to fight Huntington’s disease, while Mark Newnham describes being diagnosed with the inherited condition. Plus: Peter Beaumont describes his trip to the Costa Rican cloud forest, at threat from climate change

For Mark Newnham and thousands of others who have been told they have inherited Huntington’s disease, the future would appear bleak, a prospect of inexorable physical and mental decline. But scientists believe they are closing in on a treatment to control its worst effects.

Anushka Asthana talks to Robin McKie, the Observer’s science and environment editor, who tells her about the testing of a new drug, RG6042, that appears to reduce levels of a toxic protein that builds up in brain cells and is believed to trigger the disease. She also talks to Newnham, 32, who has tested positive for the gene.

Plus: the Guardian’s Peter Beaumont on his trip to meet Nalini Nadkarni, who has spent the past four decades studying the cloud forest in the Costa Rican town of Monteverde. In that time, global warming has wrought big changes, and is threatening to dry out the area’s lush hanging gardens for good.