Nature Neurosci. doi:10.1038/nn.2436 (2009)

Changes in gene expression caused by factors other than variation in the DNA code — 'epigenetic' changes — are partly responsible for the mental and physical health problems often associated with stress in early life.

Dietmar Spengler and his colleagues at the Max Planck Institute of Psychiatry in Munich, Germany, stressed newborn mice by separating them from their mothers. As adults, the mice secreted abnormally high levels of the stress hormone corticosterone, were less able to cope with stressful situations and had memory impairments. They also had fewer methyl groups attached to the regulatory region for the gene that encodes the hormone vasopressin, a key player in the biochemical pathway that leads to corticosterone release. The reduced methylation resulted in a rise in vasopressin expression.