The programme controls how and when brain genes are expressed at different times in a person’s life to perform a range of functions. The timing is so precise that the researchers can tell the age of a person by looking at the genes that are expressed in a sample of brain tissue.
Scientists analysed existing data which measured gene expression in brain tissue samples from across the human lifespan – from development in the womb up to 78 years of age. They found the timing of when different genes are expressed follows a strict pattern across the lifespan. Most of the changes in gene expression were completed by middle-age. The gene programme is delayed slightly in women compared with men, suggesting that the female brain ages more slowly than the male.
The team found that the biggest reorganisation of genes occurs during young adulthood, peaking around age 26. These changes affected the same genes that are associated with schizophrenia. This could explain why people with schizophrenia do not show symptoms until young adulthood, even though the genetic changes responsible for the condition are present from birth.
The study found the genetic programme is present in mice too, although it changes more rapidly across their shorter lifespan. This suggests that the calendar of brain aging is shared between all mammals and may be millions of years old.
The researchers next plan to study how the genetic programme is controlled.
Professor Seth Grant, Head of the Genes to Cognition Laboratory, Centre for Clinical Brain Sciences said “The discovery of this genetic programme opens up a completely new way to understand behaviour and brain diseases throughout life“.