One of the most devastating types of mental illness could be a by-product of the evolution of human beings’ uniquely sophisticated intelligence, a new genetic study has suggested.
Scientists have discovered that a common version of a particular gene appears both to enhance a key thinking circuit in the brain, and to be linked to a raised risk of schizophrenia.
In the study, the NIMH team examined a common variant of a gene called DARPP-32. Three quarters of the subjects studied had inherited at least one copy of the variant.
This common version of the gene appears to make the brain’s most sophisticated thinking region more efficient, the researchers found. It improves the way that information is exchanged between the striatum, a brain region that processes reward, and the prefrontal cortex, the brain’s executive hub that manages thoughts and actions.
When this circuit works efficiently, the normal outcome is more flexible thinking and improved working memory. As a result, genes such as DARPP-32 that enhance it have probably been favoured by evolution.
The same circuit, however, has also been linked to brain functions that go wrong in patients with schizophrenia. [...]