Epigenetics and the Brain

In Scientific American this month, Mount Sinai Medical Center's Eric Nestler says people's experiences can lead to epigenetic changes in the brain, which can in turn contribute to some mental illnesses. About half of all risk for conditions like addiction or depression is genetic, but researchers are beginning to see that psychiatric disorders are "precipitated in genetically susceptible individuals by environmental inputs — exposure to drugs or stress, say — and can even be influenced by random molecular events that occur during development," Nestler says. Because of this, no two people will have the same development, not even identical twins. New findings suggest that a person's experience can mark their chromosomes epigenetically, and these marks can then turn genes on or off without mutating or changing them, Nestler adds.