Genetic variants associated with schizophrenia and autism still have an impact on cognitive skills and brain structure in people who carry the genes but do not suffer from these conditions. This is one of the main findings from new research published in the journal Nature by scientists from the NEWMEDS project, which is supported by the Innovative Medicines Initiative (IMI). The findings add to our understanding of the risk factors that contribute to these conditions and could make it easier to study the neural and biochemical foundations of cognitive abilities.

It is now well known that people's genes can influence their risk of developing neuropsychiatric disorders like autism and schizophrenia. However, the picture is far from simple - most cases of these conditions are the result of complex interactions between a number of genes and the environment. This means that there are many people in the population who carry 'risk' genes but remain disease free.

In this study, researchers focused on 27 genetic variants that are known to be associated with an increased risk of schizophrenia and/or autism. The goal of the team was to determine whether healthy carriers of these variants displayed any of the cognitive difficulties or brain abnormalities found in people with schizophrenia, and then use this information to find out precisely which cognitive abnormalities put carriers at risk of developing schizophrenia. The researchers compared people with a schizophrenia diagnosis with healthy carriers of the risk variants, healthy carriers of other risk variants, as well as people who are free of the risk-associated variants. Healthy participants underwent brain scans as well as tests of cognitive skills that are known to be problematic in schizophrenia, such as attention, spatial working memory, logical memory, cognitive flexibility (the ability to think about multiple concepts or switch rapidly between different concepts), and language.

The results revealed that the cognitive abilities of healthy carriers of risk-associated genetic variants lie between those of schizophrenia patients and people without the risk variants. In addition, the brain scans showed that healthy carriers of the risk variants had brain abnormalities linked to schizophrenia and cognitive processes. The findings suggest that the cognitive abnormalities seen in people with schizophrenia are not necessarily a consequence of the disease; rather, having these cognitive problems may be a risk factor for the disease.