Our latest research was recently published in Cortex and led by Lucy Russell, who worked on this as part of her PhD. It is the first large scale study to investigate social abilities in individuals with familial forms of FTD.
Many individuals with FTD have difficulties interacting socially with other people. This can be particularly distressing for loved ones and carers because communication relies heavily on the ability to understand what others may be thinking or feeling. Some research has investigated this impairment in individuals with an unknown cause of FTD. However, very little work has investigated this in people with familial FTD, in which FTD is caused by a known genetic mutation.
In this study, we used two tasks. One investigated whether individuals are able to identify emotions in pictures of faces, and the other assessed their ability to know that others have thoughts that may be different to our own. We also investigated the brain areas that are involved in these social abilities.
627 participants took part in the study: 381 individuals with a familial form of FTD and 246 healthy controls. The individuals with familial FTD were then divided into the following genetic groups: 159 individuals with a C9orf72 expansion, 155 individuals with mutations in the GRN gene, and 67 individuals with mutations in the MAPT gene.
Comparing the individuals with familial forms of FTD to the healthy control group, we found that all individuals who had an FTD diagnosis, regardless of which genetic group was affected, had difficulties completing these two tasks. In addition, we found that individuals with C9orf72 expansions who were starting to present with very mild symptoms, also had difficulties in their ability to correctly identify emotions.
These results were also supported by the finding that brain regions previously associated with these social abilities, showed reduced grey matter volume in individuals who performed poorly on these tasks. This is important as grey matter volume is an indirect measure of functioning brain cells (neurons). So reduced volume means fewer functioning neurons in brain regions responsible for social abilities. The “basal ganglia”, a group of brain regions deep in the middle of the brain, was also associated with performance on the task, which was a new finding.
These results suggest that this emotion recognition task, along with measuring grey matter volume in certain brain regions, will be helpful to identify early changes in social abilities in individuals with C9orf72 expansions, prior to a formal clinical diagnosis of FTD being given. We hope that this will prove useful in future clinical trials, particularly for monitoring the changes in symptoms over time.