Diabetes drug metformin makes brain cells grow

The widely used diabetes drug metformin comes with a rather unexpected and alluring side effect: it encourages the growth of new neurons in the brain. The study reported in the July 6 issue of Cell Stem Cell also finds that those neural effects of the drug also make mice smarter.

The discovery is an important step toward therapies that aim to repair the brain not by introducing new stem cells but rather by spurring those that are already present into action, says the study's lead author Freda Miller of the University of Toronto-affiliated Hospital for Sick Children. The fact that it is a drug that is so widely used and so safe makes the news all that much better. Metformin is the active ingredient of Merck KGaA’s now off-patent diabetes drug Glucophage.

Earlier work by Dr Miller's team highlighted a pathway known as aPKC-CBP for its essential role in telling neural stem cells where and when to differentiate into mature neurons. As it happened, others had found before them that the same pathway is important for the metabolic effects of the drug metformin, but in liver cells.